sp_describe_cursor (Transact-SQL)

Artykuł
02/13/2015

Reports the attributes of a server cursor.

Ikona łącza do tematu Transact-SQL Syntax Conventions

Składnia

sp_describe_cursor [ @cursor_return = ] output_cursor_variable OUTPUT 
     { [ , [ @cursor_source = ] N'local'
    , [ @cursor_identity = ] N'local_cursor_name' ] 
   | [ , [ @cursor_source = ] N'global'
    , [ @cursor_identity = ] N'global_cursor_name' ] 
   | [ , [ @cursor_source = ] N'variable'
     , [ @cursor_identity = ] N'input_cursor_variable' ] 
     } 
[;]

Arguments

[ @cursor\_return= ] output_cursor_variable OUTPUT
Is the name of a declared cursor variable to receive the cursor output. output_cursor_variable is cursor, with no default, and must not be associated with any cursors at the time sp_describe_cursor is called. The cursor returned is a scrollable, dynamic, read-only cursor.
[ @cursor\_source= ] { N'local' | N'global' | N'variable' }
Specifies whether the cursor being reported on is specified by using the name of a local cursor, a global cursor, or a cursor variable. The parameter is nvarchar(30).
[ @cursor\_identity= ] N'local_cursor_name' ]
Is the name of a cursor created by a DECLARE CURSOR statement that either has the LOCAL keyword or that defaulted to LOCAL. local_cursor_name is nvarchar(128).
[ @cursor\_identity= ] N'global_cursor_name' ]
Is the name of a cursor created by a DECLARE CURSOR statement that either has the GLOBAL keyword or that defaulted to GLOBAL. global_cursor_name is nvarchar(128).

global_cursor_name can also be the name of an API server cursor that is opened by an ODBC application that then named by calling SQLSetCursorName.
[ @cursor\_identity= ] N'input_cursor_variable' ]
Is the name of a cursor variable associated with an open cursor. input_cursor_variable is nvarchar(128).

Return Code Values

None

Cursors Returned

sp_describe_cursor encapsulates its result set in a Transact-SQL cursor output parameter. This enables Transact-SQL batches, stored procedures, and triggers to work with the output one row at a time. This also means that the procedure cannot be called directly from database API functions. The cursor output parameter must be bound to a program variable, but the database APIs do not support binding cursor parameters or variables.

The following table shows the format of the cursor that is returned by using sp_describe_cursor. The format of the cursor is the same as the format returned by using sp_cursor_list.

Column name	Data type	Description
reference_name	sysname	Name used to refer to the cursor. If the reference to the cursor was through the name specified on a DECLARE CURSOR statement, the reference name is the same as cursor name. If the reference to the cursor was through a variable, the reference name is the name of the variable.
cursor_name	sysname	Name of the cursor from a DECLARE CURSOR statement. In SQL Server, if the cursor was created by setting a cursor variable to a cursor, cursor_name returns the name of the cursor variable. In earlier versions of SQL Server, this output column returns a system-generated name.
cursor_scope	tinyint	1 = LOCAL 2 = GLOBAL
status	int	Same values as reported by the CURSOR_STATUS system function: 1 = The cursor referenced by the cursor name or variable is open. If the cursor is insensitive, static, or keyset, it has at least one row. If the cursor is dynamic, the result set has zero or more rows. 0 = The cursor referenced by the cursor name or variable is open but has no rows. Dynamic cursors never return this value. -1 = The cursor referenced by the cursor name or variable is closed. -2 = Applies only to cursor variables. There is no cursor assigned to the variable. Possibly, an OUTPUT parameter assigned a cursor to the variable, but the stored procedure closed the cursor before returning. -3 = A cursor or cursor variable with the specified name does not exist, or the cursor variable has not had a cursor allocated to it.
model	tinyint	1 = Insensitive (or static) 2 = Keyset 3 = Dynamic 4 = Fast Forward
concurrency	tinyint	1 = Read-only 2 = Scroll locks 3 = Optimistic
scrollable	tinyint	0 = Forward-only 1 = Scrollable
open_status	tinyint	0 = Closed 1 = Open
cursor_rows	decimal(10,0)	Number of qualifying rows in the result set. For more information, see @@CURSOR_ROWS (Transact-SQL).
fetch_status	smallint	Status of the last fetch on this cursor. For more information, see @@FETCH_STATUS (Transact-SQL). 0 = Fetch successful. -1 = Fetch failed or is beyond the bounds of the cursor. -2 = The requested row is missing. -9 = There has been no fetch on the cursor.
column_count	smallint	Number of columns in the cursor result set.
row_count	decimal(10,0)	Number of rows affected by the last operation on the cursor. For more information, see @@ROWCOUNT (Transact-SQL).
last_operation	tinyint	Last operation performed on the cursor: 0 = No operations have been performed on the cursor. 1 = OPEN 2 = FETCH 3 = INSERT 4 = UPDATE 5 = DELETE 6 = CLOSE 7 = DEALLOCATE
cursor_handle	int	A unique value for the cursor within the scope of the server.

Uwagi

sp_describe_cursor describes the attributes that are global to a server cursor, such as the ability to scroll and update. Use sp_describe_cursor_columns for a description of the attributes of the result set returned by the cursor. Use sp_describe_cursor_tables for a report of the base tables referenced by the cursor. To obtain a report of the Transact-SQL server cursors visible on the connection, use sp_cursor_list.

A DECLARE CURSOR statement may request a cursor type that SQL Server cannot support using the SELECT statement that is contained in the DECLARE CURSOR. SQL Server implicitly converts the cursor to a type it can support using the SELECT statement. If TYPE_WARNING is specified in the DECLARE CURSOR statement, SQL Server sends the application an informational message that a conversion has been completed. sp_describe_cursor can then be called to determine the type of cursor that has been implemented.

Permissions

Requires membership in the public role.

Examples

The following example opens a global cursor and uses sp_describe_cursor to report on the attributes of the cursor.

USE AdventureWorks2012;
GO
-- Declare and open a global cursor.
DECLARE abc CURSOR STATIC FOR
SELECT LastName
FROM Person.Person;

OPEN abc;

-- Declare a cursor variable to hold the cursor output variable
-- from sp_describe_cursor.
DECLARE @Report CURSOR;

-- Execute sp_describe_cursor into the cursor variable.
EXEC master.dbo.sp_describe_cursor @cursor_return = @Report OUTPUT,
        @cursor_source = N'global', @cursor_identity = N'abc';

-- Fetch all the rows from the sp_describe_cursor output cursor.
FETCH NEXT from @Report;
WHILE (@@FETCH_STATUS <> -1)
BEGIN
    FETCH NEXT from @Report;
END

-- Close and deallocate the cursor from sp_describe_cursor.
CLOSE @Report;
DEALLOCATE @Report;
GO

-- Close and deallocate the original cursor.
CLOSE abc;
DEALLOCATE abc;
GO