SQLSetPos Function

Άρθρο
02/28/2023

Conformance
Version Introduced: ODBC 1.0 Standards Compliance: ODBC

Summary
SQLSetPos sets the cursor position in a rowset and allows an application to refresh data in the rowset or to update or delete data in the result set.

Syntax

  
SQLRETURN SQLSetPos(  
      SQLHSTMT        StatementHandle,  
      SQLSETPOSIROW   RowNumber,  
      SQLUSMALLINT    Operation,  
      SQLUSMALLINT    LockType);

Arguments

StatementHandle
[Input] Statement handle.

RowNumber
[Input] Position of the row in the rowset on which to perform the operation specified with the Operation argument. If RowNumber is 0, the operation applies to every row in the rowset.

For additional information, see "Comments."

Operation
[Input] Operation to perform:

SQL_POSITION SQL_REFRESH SQL_UPDATE SQL_DELETE

Note

The SQL_ADD value for the Operation argument has been deprecated for ODBC 3.x. ODBC 3.x drivers will need to support SQL_ADD for backward compatibility. This functionality has been replaced by a call to SQLBulkOperations with an Operation of SQL_ADD. When an ODBC 3.x application works with an ODBC 2.x driver, the Driver Manager maps a call to SQLBulkOperations with an Operation of SQL_ADD to SQLSetPos with an Operation of SQL_ADD.

For more information, see "Comments."

LockType
[Input] Specifies how to lock the row after performing the operation specified in the Operation argument.

SQL_LOCK_NO_CHANGE SQL_LOCK_EXCLUSIVE SQL_LOCK_UNLOCK

For more information, see "Comments."

Returns

SQL_SUCCESS, SQL_SUCCESS_WITH_INFO, SQL_NEED_DATA, SQL_STILL_EXECUTING, SQL_ERROR, or SQL_INVALID_HANDLE.

Diagnostics

When SQLSetPos returns SQL_ERROR or SQL_SUCCESS_WITH_INFO, an associated SQLSTATE value may be obtained by calling SQLGetDiagRec with a HandleType of SQL_HANDLE_STMT and a Handle of StatementHandle. The following table lists the SQLSTATE values commonly returned by SQLSetPos and explains each one in the context of this function; the notation "(DM)" precedes the descriptions of SQLSTATEs returned by the Driver Manager. The return code associated with each SQLSTATE value is SQL_ERROR, unless noted otherwise.

For all those SQLSTATEs that can return SQL_SUCCESS_WITH_INFO or SQL_ERROR (except 01xxx SQLSTATEs), SQL_SUCCESS_WITH_INFO is returned if an error occurs on one or more, but not all, rows of a multirow operation, and SQL_ERROR is returned if an error occurs on a single-row operation.

SQLSTATE	Error	Description
01000	General warning	Driver-specific informational message. (Function returns SQL_SUCCESS_WITH_INFO.)
01001	Cursor operation conflict	The Operation argument was SQL_DELETE or SQL_UPDATE, and no rows or more than one row were deleted or updated. (For more information about updates to more than one row, see the description of the SQL_ATTR_SIMULATE_CURSOR Attribute in SQLSetStmtAttr.) (Function returns SQL_SUCCESS_WITH_INFO.) The Operation argument was SQL_DELETE or SQL_UPDATE, and the operation failed because of optimistic concurrency. (Function returns SQL_SUCCESS_WITH_INFO.)
01004	String data right truncation	The Operation argument was SQL_REFRESH, and string or binary data returned for a column or columns with a data type of SQL_C_CHAR or SQL_C_BINARY resulted in the truncation of nonblank character or non-NULL binary data.
01S01	Error in row	The RowNumber argument was 0, and an error occurred in one or more rows while performing the operation specified with the Operation argument. (SQL_SUCCESS_WITH_INFO is returned if an error occurs on one or more, but not all, rows of a multirow operation, and SQL_ERROR is returned if an error occurs on a single-row operation.) (This SQLSTATE is returned only when SQLSetPos is called after SQLExtendedFetch, if the driver is an ODBC 2.x driver and the cursor library is not used.)
01S07	Fractional truncation	The Operation argument was SQL_REFRESH, the data type of the application buffer was not SQL_C_CHAR or SQL_C_BINARY, and the data returned to application buffers for one or more columns was truncated. For numeric data types, the fractional part of the number was truncated. For time, timestamp, and interval data types containing a time component, the fractional portion of the time was truncated. (Function returns SQL_SUCCESS_WITH_INFO.)
07006	Restricted data type attribute violation	The data value of a column in the result set could not be converted to the data type specified by TargetType in the call to SQLBindCol.
07009	Invalid descriptor index	The argument Operation was SQL_REFRESH or SQL_UPDATE, and a column was bound with a column number greater than the number of columns in the result set.
21S02	Degree of derived table does not match column list	The argument Operation was SQL_UPDATE, and no columns were updatable because all columns were either unbound, read-only, or the value in the bound length/indicator buffer was SQL_COLUMN_IGNORE.
22001	String data, right truncation	The Operation argument was SQL_UPDATE, and the assignment of a character or binary value to a column resulted in the truncation of nonblank (for characters) or non-null (for binary) characters or bytes.
22003	Numeric value out of range	The argument Operation was SQL_UPDATE, and the assignment of a numeric value to a column in the result set caused the whole (as opposed to fractional) part of the number to be truncated. The argument Operation was SQL_REFRESH, and returning the numeric value for one or more bound columns would have caused a loss of significant digits.
22007	Invalid datetime format	The argument Operation was SQL_UPDATE, and the assignment of a date or timestamp value to a column in the result set caused the year, month, or day field to be out of range. The argument Operation was SQL_REFRESH, and returning the date or timestamp value for one or more bound columns would have caused the year, month, or day field to be out of range.
22008	Date/time field overflow	The Operation argument was SQL_UPDATE, and the performance of datetime arithmetic on data being sent to a column in the result set resulted in a datetime field (the year, month, day, hour, minute, or second field) of the result being outside the permissible range of values for the field, or being invalid based on the Gregorian calendar's natural rules for datetimes. The Operation argument was SQL_REFRESH, and the performance of datetime arithmetic on data being retrieved from the result set resulted in a datetime field (the year, month, day, hour, minute, or second field) of the result being outside the permissible range of values for the field, or being invalid based on the Gregorian calendar's natural rules for datetimes.
22015	Interval field overflow	The Operation argument was SQL_UPDATE, and the assignment of an exact numeric or interval C type to an interval SQL data type caused a loss of significant digits. The Operation argument was SQL_UPDATE; when assigning to an interval SQL type, there was no representation of the value of the C type in the interval SQL type. The Operation argument was SQL_REFRESH, and assigning from an exact numeric or interval SQL type to an interval C type caused a loss of significant digits in the leading field. The Operation argument was SQL_ REFRESH; when assigning to an interval C type, there was no representation of the value of the SQL type in the interval C type.
22018	Invalid character value for cast specification	The Operation argument was SQL_REFRESH; the C type was an exact or approximate numeric, a datetime, or an interval data type; the SQL type of the column was a character data type; and the value in the column was not a valid literal of the bound C type. The argument Operation was SQL_UPDATE; the SQL type was an exact or approximate numeric, a datetime, or an interval data type; the C type was SQL_C_CHAR; and the value in the column was not a valid literal of the bound SQL type.
23000	Integrity constraint violation	The argument Operation was SQL_DELETE or SQL_UPDATE, and an integrity constraint was violated.
24000	Invalid cursor state	The StatementHandle was in an executed state, but no result set was associated with the StatementHandle. (DM) A cursor was open on the StatementHandle, but SQLFetch or SQLFetchScroll had not been called. A cursor was open on the StatementHandle, and SQLFetch or SQLFetchScroll had been called, but the cursor was positioned before the start of the result set or after the end of the result set. The argument Operation was SQL_DELETE, SQL_REFRESH, or SQL_UPDATE, and the cursor was positioned before the start of the result set or after the end of the result set.
40001	Serialization failure	The transaction was rolled back due to a resource deadlock with another transaction.
40003	Statement completion unknown	The associated connection failed during the execution of this function, and the state of the transaction cannot be determined.
42000	Syntax error or access violation	The driver was unable to lock the row as needed to perform the operation requested in the argument Operation. The driver was unable to lock the row as requested in the argument LockType.
44000	WITH CHECK OPTION violation	The Operation argument was SQL_UPDATE, and the update was performed on a viewed table or a table derived from the viewed table which was created by specifying WITH CHECK OPTION, such that one or more rows affected by the update will no longer be present in the viewed table.
HY000	General error	An error occurred for which there was no specific SQLSTATE and for which no implementation-specific SQLSTATE was defined. The error message returned by SQLGetDiagRec in the *MessageText buffer describes the error and its cause.
HY001	Memory allocation error	The driver was unable to allocate memory required to support execution or completion of the function.
HY008	Operation canceled	Asynchronous processing was enabled for the StatementHandle. The function was called, and before it completed execution, SQLCancel or SQLCancelHandle was called on the StatementHandle, and then the function was called again on the StatementHandle. The function was called, and before it completed execution, SQLCancel or SQLCancelHandle was called on the StatementHandle from a different thread in a multithread application.
HY010	Function sequence error	(DM) An asynchronously executing function was called for the connection handle that is associated with the StatementHandle. This asynchronous function was still executing when the SQLSetPos function was called. (DM) The specified StatementHandle was not in an executed state. The function was called without first calling SQLExecDirect, SQLExecute, or a catalog function. (DM) An asynchronously executing function (not this one) was called for the StatementHandle and was still executing when this function was called. (DM) SQLExecute, SQLExecDirect, SQLBulkOperations, or SQLSetPos was called for the StatementHandle and returned SQL_NEED_DATA. This function was called before data was sent for all data-at-execution parameters or columns. (DM) The driver was an ODBC 2.x driver, and SQLSetPos was called for a StatementHandle after SQLFetch was called.
HY011	Attribute cannot be set now	(DM) The driver was an ODBC 2.x driver; the SQL_ATTR_ROW_STATUS_PTR statement attribute was set; then SQLSetPos was called before SQLFetch, SQLFetchScroll, or SQLExtendedFetch was called.
HY013	Memory management error	The function call could not be processed because the underlying memory objects could not be accessed, possibly because of low memory conditions.
HY090	Invalid string or buffer length	The Operation argument was SQL_UPDATE, a data value was a null pointer, and the column length value was not 0, SQL_DATA_AT_EXEC, SQL_COLUMN_IGNORE, SQL_NULL_DATA, or less than or equal to SQL_LEN_DATA_AT_EXEC_OFFSET. The Operation argument was SQL_UPDATE; a data value was not a null pointer; the C data type was SQL_C_BINARY or SQL_C_CHAR; and the column length value was less than 0 but not equal to SQL_DATA_AT_EXEC, SQL_COLUMN_IGNORE, SQL_NTS, or SQL_NULL_DATA, or less than or equal to SQL_LEN_DATA_AT_EXEC_OFFSET. The value in a length/indicator buffer was SQL_DATA_AT_EXEC; the SQL type was either SQL_LONGVARCHAR, SQL_LONGVARBINARY, or a long data source-specific data type; and the SQL_NEED_LONG_DATA_LEN information type in SQLGetInfo was "Y".
HY092	Invalid attribute identifier	(DM) The value specified for the Operation argument was invalid. (DM) The value specified for the LockType argument was invalid. The Operation argument was SQL_UPDATE or SQL_DELETE, and the SQL_ATTR_CONCURRENCY statement attribute was SQL_ATTR_CONCUR_READ_ONLY.
HY107	Row value out of range	The value specified for the argument RowNumber was greater than the number of rows in the rowset.
HY109	Invalid cursor position	The cursor associated with the StatementHandle was defined as forward-only, so the cursor could not be positioned within the rowset. See the description for the SQL_ATTR_CURSOR_TYPE attribute in SQLSetStmtAttr. The Operation argument was SQL_UPDATE, SQL_DELETE, or SQL_REFRESH, and the row identified by the RowNumber argument had been deleted or had not been fetched. (DM) The RowNumber argument was 0, and the Operation argument was SQL_POSITION. SQLSetPos was called after SQLBulkOperations was called and before SQLFetchScroll or SQLFetch was called.
HY117	Connection is suspended due to unknown transaction state. Only disconnect and read-only functions are allowed.	(DM) For more information about suspended state, see SQLEndTran Function.
HYC00	Optional feature not implemented	The driver or data source does not support the operation requested in the Operation argument or the LockType argument.
HYT00	Timeout expired	The query timeout period expired before the data source returned the result set. The timeout period is set through SQLSetStmtAttr with an Attribute of SQL_ATTR_QUERY_TIMEOUT.
HYT01	Connection timeout expired	The connection timeout period expired before the data source responded to the request. The connection timeout period is set through SQLSetConnectAttr, SQL_ATTR_CONNECTION_TIMEOUT.
IM001	Driver does not support this function	(DM) The driver associated with the StatementHandle does not support the function.
IM017	Polling is disabled in asynchronous notification mode	Whenever the notification model is used, polling is disabled.
IM018	SQLCompleteAsync has not been called to complete the previous asynchronous operation on this handle.	If the previous function call on the handle returns SQL_STILL_EXECUTING and if notification mode is enabled, SQLCompleteAsync must be called on the handle to do post-processing and complete the operation.

Comments

Caution

For information on the statement states that SQLSetPos can be called in and what it needs to do for compatibility with ODBC 2.x applications, see Block Cursors, Scrollable Cursors, and Backward Compatibility.

RowNumber Argument

The RowNumber argument specifies the number of the row in the rowset on which to perform the operation specified by the Operation argument. If RowNumber is 0, the operation applies to every row in the rowset. RowNumber must be a value from 0 to the number of rows in the rowset.

Note

In the C language, arrays are 0-based and the RowNumber argument is 1-based. For example, to update the fifth row of the rowset, an application modifies the rowset buffers at array index 4 but specifies a RowNumber of 5.

All operations position the cursor on the row specified by RowNumber. The following operations require a cursor position:

Positioned update and delete statements.
Calls to SQLGetData.
Calls to SQLSetPos with the SQL_DELETE, SQL_REFRESH, and SQL_UPDATE options.

For example, if RowNumber is 2 for a call to SQLSetPos with an Operation of SQL_DELETE, the cursor is positioned on the second row of the rowset and that row is deleted. The entry in the implementation row status array (pointed to by the SQL_ATTR_ROW_STATUS_PTR statement attribute) for the second row is changed to SQL_ROW_DELETED.

An application can specify a cursor position when it calls SQLSetPos. Generally, it calls SQLSetPos with the SQL_POSITION or SQL_REFRESH operation to position the cursor before executing a positioned update or delete statement or calling SQLGetData.

Operation Argument

The Operation argument supports the following operations. To determine which options are supported by a data source, an application calls SQLGetInfo with the SQL_DYNAMIC_CURSOR_ATTRIBUTES1, SQL_FORWARD_ONLY_CURSOR_ATTRIBUTES1, SQL_KEYSET_CURSOR_ATTRIBUTES1, or SQL_STATIC_CURSOR_ATTRIBUTES1 information type (depending on the type of the cursor).

Operation argument	Operation
SQL_POSITION	The driver positions the cursor on the row specified by RowNumber. The contents of the row status array pointed to by the SQL_ATTR_ROW_OPERATION_PTR statement attribute are ignored for the SQL_POSITION Operation.
SQL_REFRESH	The driver positions the cursor on the row specified by RowNumber and refreshes data in the rowset buffers for that row. For more information about how the driver returns data in the rowset buffers, see the descriptions of row-wise and column-wise binding in SQLBindCol. SQLSetPos with an Operation of SQL_REFRESH updates the status and content of the rows within the current fetched rowset. This includes refreshing the bookmarks. Because the data in the buffers is refreshed but not refetched, the membership in the rowset is fixed. This is different from the refresh performed by a call to SQLFetchScroll with a FetchOrientation of SQL_FETCH_RELATIVE and a RowNumber equal to 0, which refetches the rowset from the result set so that it can show added data and remove deleted data if those operations are supported by the driver and the cursor. A successful refresh with SQLSetPos will not change a row status of SQL_ROW_DELETED. Deleted rows within the rowset will continue to be marked as deleted until the next fetch. The rows will disappear at the next fetch if the cursor supports packing (in which a subsequent SQLFetch or SQLFetchScroll does not return deleted rows). Added rows do not appear when a refresh with SQLSetPos is performed. This behavior is different from SQLFetchScroll with a FetchType of SQL_FETCH_RELATIVE and a RowNumber equal to 0, which also refreshes the current rowset but will show added records or pack deleted records if these operations are supported by the cursor. A successful refresh with SQLSetPos will change a row status of SQL_ROW_ADDED to SQL_ROW_SUCCESS (if the row status array exists). A successful refresh with SQLSetPos will change a row status of SQL_ROW_UPDATED to the row's new status (if the row status array exists). If an error occurs in a SQLSetPos operation on a row, the row status is set to SQL_ROW_ERROR (if the row status array exists). For a cursor opened with an SQL_ATTR_CONCURRENCY statement attribute of SQL_CONCUR_ROWVER or SQL_CONCUR_VALUES, a refresh with SQLSetPos might update the optimistic concurrency values used by the data source to detect that the row has changed. If this occurs, the row versions or values used to ensure cursor concurrency are updated whenever the rowset buffers are refreshed from the server. This occurs for each row that is refreshed. The contents of the row status array pointed to by the SQL_ATTR_ROW_OPERATION_PTR statement attribute are ignored for the SQL_REFRESH Operation.
SQL_UPDATE	The driver positions the cursor on the row specified by RowNumber and updates the underlying row of data with the values in the rowset buffers (the TargetValuePtr argument in SQLBindCol). It retrieves the lengths of the data from the length/indicator buffers (the StrLen_or_IndPtr argument in SQLBindCol). If the length of any column is SQL_COLUMN_IGNORE, the column is not updated. After updating the row, the driver changes the corresponding element of the row status array to SQL_ROW_UPDATED or SQL_ROW_SUCCESS_WITH_INFO (if the row status array exists). It is driver-defined what the behavior is if SQLSetPos with an Operation argument of SQL_UPDATE is called on a cursor that contains duplicate columns. The driver can return a driver-defined SQLSTATE, can update the first column that appears in the result set, or perform other driver-defined behavior. The row operation array pointed to by the SQL_ATTR_ROW_OPERATION_PTR statement attribute can be used to indicate that a row in the current rowset should be ignored during a bulk update. For more information, see "Status and Operation Arrays" later in this function reference.
SQL_DELETE	The driver positions the cursor on the row specified by RowNumber and deletes the underlying row of data. It changes the corresponding element of the row status array to SQL_ROW_DELETED. After the row has been deleted, the following are not valid for the row: positioned update and delete statements, calls to SQLGetData, and calls to SQLSetPos with Operation set to anything except SQL_POSITION. For drivers that support packing, the row is deleted from the cursor when new data is retrieved from the data source. Whether the row remains visible depends on the cursor type. For example, deleted rows are visible to static and keyset-driven cursors but invisible to dynamic cursors. The row operation array pointed to by the SQL_ATTR_ROW_OPERATION_PTR statement attribute can be used to indicate that a row in the current rowset should be ignored during a bulk delete. For more information, see "Status and Operation Arrays" later in this function reference.

LockType Argument

The LockType argument provides a way for applications to control concurrency. In most cases, data sources that support concurrency levels and transactions will support only the SQL_LOCK_NO_CHANGE value of the LockType argument. The LockType argument is generally used only for file-based support.

The LockType argument specifies the lock state of the row after SQLSetPos has been executed. If the driver is unable to lock the row either to perform the requested operation or to satisfy the LockType argument, it returns SQL_ERROR and SQLSTATE 42000 (Syntax error or access violation).

Although the LockType argument is specified for a single statement, the lock accords the same privileges to all statements on the connection. In particular, a lock that is acquired by one statement on a connection can be unlocked by a different statement on the same connection.

A row locked through SQLSetPos remains locked until the application calls SQLSetPos for the row with LockType set to SQL_LOCK_UNLOCK, or until the application calls SQLFreeHandle for the statement or SQLFreeStmt with the SQL_CLOSE option. For a driver that supports transactions, a row locked through SQLSetPos is unlocked when the application calls SQLEndTran to commit or roll back a transaction on the connection (if a cursor is closed when a transaction is committed or rolled back, as indicated by the SQL_CURSOR_COMMIT_BEHAVIOR and SQL_CURSOR_ROLLBACK_BEHAVIOR information types returned by SQLGetInfo).

The LockType argument supports the following types of locks. To determine which locks are supported by a data source, an application calls SQLGetInfo with the SQL_DYNAMIC_CURSOR_ATTRIBUTES1, SQL_FORWARD_ONLY_CURSOR_ATTRIBUTES1, SQL_KEYSET_CURSOR_ATTRIBUTES1, or SQL_STATIC_CURSOR_ATTRIBUTES1 information type (depending on the type of the cursor).

LockType argument	Lock type
SQL_LOCK_NO_CHANGE	The driver or data source ensures that the row is in the same locked or unlocked state as it was before SQLSetPos was called. This value of LockType allows data sources that do not support explicit row-level locking to use whatever locking is required by the current concurrency and transaction isolation levels.
SQL_LOCK_EXCLUSIVE	The driver or data source locks the row exclusively. A statement on a different connection or in a different application cannot be used to acquire any locks on the row.
SQL_LOCK_UNLOCK	The driver or data source unlocks the row.

If a driver supports SQL_LOCK_EXCLUSIVE but does not support SQL_LOCK_UNLOCK, a row that is locked will remain locked until one of the function calls described in the previous paragraph occurs.

If a driver supports SQL_LOCK_EXCLUSIVE but does not support SQL_LOCK_UNLOCK, a row that is locked will remain locked until the application calls SQLFreeHandle for the statement or SQLFreeStmt with the SQL_CLOSE option. If the driver supports transactions and closes the cursor upon committing or rolling back the transaction, the application calls SQLEndTran.

For the update and delete operations in SQLSetPos, the application uses the LockType argument as follows:

To guarantee that a row does not change after it is retrieved, an application calls SQLSetPos with Operation set to SQL_REFRESH and LockType set to SQL_LOCK_EXCLUSIVE.
If the application sets LockType to SQL_LOCK_NO_CHANGE, the driver guarantees that an update or delete operation will succeed only if the application specified SQL_CONCUR_LOCK for the SQL_ATTR_CONCURRENCY statement attribute.
If the application specifies SQL_CONCUR_ROWVER or SQL_CONCUR_VALUES for the SQL_ATTR_CONCURRENCY statement attribute, the driver compares row versions or values and rejects the operation if the row has changed since the application fetched the row.
If the application specifies SQL_CONCUR_READ_ONLY for the SQL_ATTR_CONCURRENCY statement attribute, the driver rejects any update or delete operation.

For more information about the SQL_ATTR_CONCURRENCY statement attribute, see SQLSetStmtAttr.

Status and Operation Arrays

The following status and operation arrays are used when calling SQLSetPos:

The row status array (as pointed to by the SQL_DESC_ARRAY_STATUS_PTR field in the IRD and the SQL_ATTR_ROW_STATUS_ARRAY statement attribute) contains status values for each row of data in the rowset. The driver sets the status values in this array after a call to SQLFetch, SQLFetchScroll, SQLBulkOperations, or SQLSetPos. This array is pointed to by the SQL_ATTR_ROW_STATUS_PTR statement attribute.
The row operation array (as pointed to by the SQL_DESC_ARRAY_STATUS_PTR field in the ARD and the SQL_ATTR_ROW_OPERATION_ARRAY statement attribute) contains a value for each row in the rowset that indicates whether a call to SQLSetPos for a bulk operation is ignored or performed. Each element in the array is set to either SQL_ROW_PROCEED (the default) or SQL_ROW_IGNORE. This array is pointed to by the SQL_ATTR_ROW_OPERATION_PTR statement attribute.

The number of elements in the status and operation arrays must equal the number of rows in the rowset (as defined by the SQL_ATTR_ROW_ARRAY_SIZE statement attribute).

For information about the row status array, see SQLFetch. For information about the row operation array, see "Ignoring a Row in a Bulk Operation," later in this section.

Using SQLSetPos

Before an application calls SQLSetPos, it must perform the following sequence of steps:

If the application will call SQLSetPos with Operation set to SQL_UPDATE, call SQLBindCol (or SQLSetDescRec) for each column to specify its data type and bind buffers for the column's data and length.
If the application will call SQLSetPos with Operation set to SQL_DELETE or SQL_UPDATE, call SQLColAttribute to make sure that the columns to be deleted or updated are updatable.
Call SQLExecDirect, SQLExecute, or a catalog function to create a result set.
Call SQLFetch or SQLFetchScroll to retrieve the data.

For more information about using SQLSetPos, see Updating Data with SQLSetPos.

Deleting Data Using SQLSetPos

To delete data with SQLSetPos, an application calls SQLSetPos with RowNumber set to the number of the row to delete and Operation set to SQL_DELETE.

After the data has been deleted, the driver changes the value in the implementation row status array for the appropriate row to SQL_ROW_DELETED (or SQL_ROW_ERROR).

Updating Data Using SQLSetPos

An application can pass the value for a column either in the bound data buffer or with one or more calls to SQLPutData. Columns whose data is passed with SQLPutData are known as data-at-execution columns. These are commonly used to send data for SQL_LONGVARBINARY and SQL_LONGVARCHAR columns and can be mixed with other columns.

To update data with SQLSetPos, an application:

Places values in the data and length/indicator buffers bound with SQLBindCol:
- For normal columns, the application places the new column value in the *TargetValuePtr buffer and the length of that value in the *StrLen_or_IndPtr buffer. If the row should not be updated, the application places SQL_ROW_IGNORE in that row's element of the row operation array.
- For data-at-execution columns, the application places an application-defined value, such as the column number, in the *TargetValuePtr buffer. The value can be used later to identify the column.
  
  The application places the result of the SQL_LEN_DATA_AT_EXEC(length) macro in the *StrLen_or_IndPtr buffer. If the SQL data type of the column is SQL_LONGVARBINARY, SQL_LONGVARCHAR, or a long data source-specific data type and the driver returns "Y" for the SQL_NEED_LONG_DATA_LEN information type in SQLGetInfo, length is the number of bytes of data to be sent for the parameter; otherwise, it must be a non-negative value and is ignored.
Calls SQLSetPos with the Operation argument set to SQL_UPDATE to update the row of data.
- If there are no data-at-execution columns, the process is complete.
- If there are any data-at-execution columns, the function returns SQL_NEED_DATA and proceeds to step 3.
Calls SQLParamData to retrieve the address of the *TargetValuePtr buffer for the first data-at-execution column to be processed. SQLParamData returns SQL_NEED_DATA. The application retrieves the application-defined value from the *TargetValuePtr buffer.

Note

Although data-at-execution parameters are similar to data-at-execution columns, the value returned by SQLParamData is different for each.

Note

Data-at-execution parameters are parameters in a SQL statement for which data will be sent with SQLPutData when the statement is executed with SQLExecDirect or SQLExecute. They are bound with SQLBindParameter or by setting descriptors with SQLSetDescRec. The value returned by SQLParamData is a 32-bit value passed to SQLBindParameter in the ParameterValuePtr argument.

Note

Data-at-execution columns are columns in a rowset for which data will be sent with SQLPutData when a row is updated with SQLSetPos. They are bound with SQLBindCol. The value returned by SQLParamData is the address of the row in the *TargetValuePtr buffer that is being processed.
Calls SQLPutData one or more times to send data for the column. More than one call is needed if all the data values cannot be returned in the *TargetValuePtr buffer specified in SQLPutData; multiple calls to SQLPutData for the same column are allowed only when sending character C data to a column with a character, binary, or data source-specific data type or when sending binary C data to a column with a character, binary, or data source-specific data type.
Calls SQLParamData again to signal that all data has been sent for the column.
- If there are more data-at-execution columns, SQLParamData returns SQL_NEED_DATA and the address of the TargetValuePtr buffer for the next data-at-execution column to be processed. The application repeats steps 4 and 5.
- If there are no more data-at-execution columns, the process is complete. If the statement was executed successfully, SQLParamData returns SQL_SUCCESS or SQL_SUCCESS_WITH_INFO; if the execution failed, it returns SQL_ERROR. At this point, SQLParamData can return any SQLSTATE that can be returned by SQLSetPos.

If data has been updated, the driver changes the value in the implementation row status array for the appropriate row to SQL_ROW_UPDATED.

If the operation is canceled or an error occurs in SQLParamData or SQLPutData, after SQLSetPos returns SQL_NEED_DATA and before data is sent for all data-at-execution columns, the application can call only SQLCancel, SQLGetDiagField, SQLGetDiagRec, SQLGetFunctions, SQLParamData, or SQLPutData for the statement or the connection associated with the statement. If it calls any other function for the statement or the connection associated with the statement, the function returns SQL_ERROR and SQLSTATE HY010 (Function sequence error).

If the application calls SQLCancel while the driver still needs data for data-at-execution columns, the driver cancels the operation. The application can then call SQLSetPos again; canceling does not affect the cursor state or the current cursor position.

When the SELECT-list of the query specification associated with the cursor contains more than one reference to the same column, whether an error is generated or the driver ignores the duplicated references and performs the requested operations is driver-defined.

Performing Bulk Operations

If the RowNumber argument is 0, the driver performs the operation specified in the Operation argument for every row in the rowset that has a value of SQL_ROW_PROCEED in its field in the row operation array pointed to by SQL_ATTR_ROW_OPERATION_PTR statement attribute. This is a valid value of the RowNumber argument for an Operation argument of SQL_DELETE, SQL_REFRESH, or SQL_UPDATE, but not SQL_POSITION. SQLSetPos with an Operation of SQL_POSITION and a RowNumber equal to 0 will return SQLSTATE HY109 (Invalid cursor position).

If an error occurs that pertains to the entire rowset, such as SQLSTATE HYT00 (Timeout expired), the driver returns SQL_ERROR and the appropriate SQLSTATE. The contents of the rowset buffers are undefined, and the cursor position is unchanged.

If an error occurs that pertains to a single row, the driver:

Sets the element for the row in the row status array pointed to by the SQL_ATTR_ROW_STATUS_PTR statement attribute to SQL_ROW_ERROR.
Posts one or more additional SQLSTATEs for the error in the error queue and sets the SQL_DIAG_ROW_NUMBER field in the diagnostic data structure.

After it has processed the error or warning, if the driver completes the operation for the remaining rows in the rowset, it returns SQL_SUCCESS_WITH_INFO. Thus, for each row that returned an error, the error queue contains zero or more additional SQLSTATEs. If the driver stops the operation after it has processed the error or warning, it returns SQL_ERROR.

If the driver returns any warnings, such as SQLSTATE 01004 (Data truncated), it returns warnings that apply to the entire rowset or to unknown rows in the rowset before it returns the error information that applies to specific rows. It returns warnings for specific rows along with any other error information about those rows.

If RowNumber is equal to 0 and Operation is SQL_UPDATE, SQL_REFRESH, or SQL_DELETE, the number of rows that SQLSetPos operates on is pointed to by the SQL_ATTR_ROWS_FETCHED_PTR statement attribute.

If RowNumber is equal to 0 and Operation is SQL_DELETE, SQL_REFRESH, or SQL_UPDATE, the current row after the operation is the same as the current row before the operation.

Ignoring a Row in a Bulk Operation

The row operation array can be used to indicate that a row in the current rowset should be ignored during a bulk operation using SQLSetPos. To direct the driver to ignore one or more rows during a bulk operation, an application should perform the following steps:

Call SQLSetStmtAttr to set the SQL_ATTR_ROW_OPERATION_PTR statement attribute to point to an array of SQLUSMALLINTs. This field can also be set by calling SQLSetDescField to set the SQL_DESC_ARRAY_STATUS_PTR header field of the ARD, which requires that an application obtains the descriptor handle.
Set each element of the row operation array to one of two values:
- SQL_ROW_IGNORE, to indicate that the row is excluded for the bulk operation.
- SQL_ROW_PROCEED, to indicate that the row is included in the bulk operation. (This is the default value.)
Call SQLSetPos to perform the bulk operation.

The following rules apply to the row operation array:

SQL_ROW_IGNORE and SQL_ROW_PROCEED affect only bulk operations using SQLSetPos with an Operation of SQL_DELETE or SQL_UPDATE. They do not affect calls to SQLSetPos with an Operation of SQL_REFRESH or SQL_POSITION.
The pointer is set to null by default.
If the pointer is null, all rows are updated as if all elements were set to SQL_ROW_PROCEED.
Setting an element to SQL_ROW_PROCEED does not guarantee that the operation will occur on that particular row. For example, if a certain row in the rowset has the status SQL_ROW_ERROR, the driver might not be able to update that row regardless of whether the application specified SQL_ROW_PROCEED. An application must always check the row status array to see whether the operation was successful.
SQL_ROW_PROCEED is defined as 0 in the header file. An application can initialize the row operation array to 0 in order to process all rows.
If element number "n" in the row operation array is set to SQL_ROW_IGNORE and SQLSetPos is called to perform a bulk update or delete operation, the nth row in the rowset remains unchanged after the call to SQLSetPos.
An application should automatically set a read-only column to SQL_ROW_IGNORE.

Ignoring a Column in a Bulk Operation

To avoid unnecessary processing diagnostics generated by attempted updates to one or more read-only columns, an application can set the value in the bound length/indicator buffer to SQL_COLUMN_IGNORE. For more information, see SQLBindCol.

Code Example

In the following example, an application allows a user to browse the ORDERS table and update order status. The cursor is keyset-driven with a rowset size of 20 and uses optimistic concurrency control comparing row versions. After each rowset is fetched, the application prints it and allows the user to select and update the status of an order. The application uses SQLSetPos to position the cursor on the selected row and performs a positioned update of the row. (Error handling is omitted for clarity.)

#define ROWS 20  
#define STATUS_LEN 6  
  
SQLCHAR        szStatus[ROWS][STATUS_LEN], szReply[3];  
SQLINTEGER     cbStatus[ROWS], cbOrderID;  
SQLUSMALLINT   rgfRowStatus[ROWS];  
SQLUINTEGER    sOrderID, crow = ROWS, irow;  
SQLHSTMT       hstmtS, hstmtU;  
  
SQLSetStmtAttr(hstmtS, SQL_ATTR_CONCURRENCY, (SQLPOINTER) SQL_CONCUR_ROWVER, 0);  
SQLSetStmtAttr(hstmtS, SQL_ATTR_CURSOR_TYPE, (SQLPOINTER) SQL_CURSOR_KEYSET_DRIVEN, 0);  
SQLSetStmtAttr(hstmtS, SQL_ATTR_ROW_ARRAY_SIZE, (SQLPOINTER) ROWS, 0);  
SQLSetStmtAttr(hstmtS, SQL_ATTR_ROW_STATUS_PTR, (SQLPOINTER) rgfRowStatus, 0);  
SQLSetCursorName(hstmtS, "C1", SQL_NTS);  
SQLExecDirect(hstmtS, "SELECT ORDERID, STATUS FROM ORDERS ", SQL_NTS);  
  
SQLBindCol(hstmtS, 1, SQL_C_ULONG, &sOrderID, 0, &cbOrderID);  
SQLBindCol(hstmtS, 2, SQL_C_CHAR, szStatus, STATUS_LEN, &cbStatus);  
  
while ((retcode == SQLFetchScroll(hstmtS, SQL_FETCH_NEXT, 0)) != SQL_ERROR) {  
   if (retcode == SQL_NO_DATA_FOUND)  
      break;  
   for (irow = 0; irow < crow; irow++) {  
      if (rgfRowStatus[irow] != SQL_ROW_DELETED)  
         printf("%2d %5d %*s\n", irow+1, sOrderID, NAME_LEN-1, szStatus[irow]);  
   }  
   while (TRUE) {  
      printf("\nRow number to update?");  
      gets_s(szReply, 3);  
      irow = atoi(szReply);  
      if (irow > 0 && irow <= crow) {  
         printf("\nNew status?");  
         gets_s(szStatus[irow-1], (ROWS * STATUS_LEN));  
         SQLSetPos(hstmtS, irow, SQL_POSITION, SQL_LOCK_NO_CHANGE);  
         SQLPrepare(hstmtU,  
          "UPDATE ORDERS SET STATUS=? WHERE CURRENT OF C1", SQL_NTS);  
         SQLBindParameter(hstmtU, 1, SQL_PARAM_INPUT,  
            SQL_C_CHAR, SQL_CHAR,  
            STATUS_LEN, 0, szStatus[irow], 0, NULL);  
         SQLExecute(hstmtU);  
      } else if (irow == 0) {  
         break;  
      }  
   }  
}

For more examples, see Positioned Update and Delete Statements and Updating Rows in the Rowset with SQLSetPos.

For information about	See
Binding a buffer to a column in a result set	SQLBindCol Function
Performing bulk operations that do not relate to the block cursor position	SQLBulkOperations Function
Canceling statement processing	SQLCancel Function
Fetching a block of data or scrolling through a result set	SQLFetchScroll Function
Getting a single field of a descriptor	SQLGetDescField Function
Getting multiple fields of a descriptor	SQLGetDescRec Function
Setting a single field of a descriptor	SQLSetDescField Function
Setting multiple fields of a descriptor	SQLSetDescRec Function
Setting a statement attribute	SQLSetStmtAttr Function

Κοινή χρήση μέσω

SQLSetPos Function

Syntax

Arguments

Returns

Diagnostics

Comments

RowNumber Argument

Operation Argument

LockType Argument

Status and Operation Arrays

Using SQLSetPos

Deleting Data Using SQLSetPos

Updating Data Using SQLSetPos

To update data with SQLSetPos, an application:

Performing Bulk Operations

Ignoring a Row in a Bulk Operation

Ignoring a Column in a Bulk Operation

Code Example

See Also

Σχόλια

Πρόσθετοι πόροι

Κοινή χρήση μέσω

SQLSetPos Function

Syntax

Arguments

Returns

Diagnostics

Comments

RowNumber Argument

Operation Argument

LockType Argument

Status and Operation Arrays

Using SQLSetPos

Deleting Data Using SQLSetPos

Updating Data Using SQLSetPos

To update data with SQLSetPos, an application:

Performing Bulk Operations

Ignoring a Row in a Bulk Operation

Ignoring a Column in a Bulk Operation

Code Example

Related Functions

See Also

Σχόλια

Πρόσθετοι πόροι