SQL to C: Day-Time Intervals

The identifiers for the day-time interval ODBC SQL data types are the following:

• SQL_INTERVAL_DAY
• SQL_INTERVAL_DAY_TO_MINUTE
• SQL_INTERVAL_HOUR
• SQL_INTERVAL_DAY_TO_SECOND
• SQL_INTERVAL_MINUTE
• SQL_INTERVAL_HOUR_TO_MINUTE
• SQL_INTERVAL_SECOND
• SQL_INTERVAL_HOUR_TO_SECOND
• SQL_INTERVAL_DAY_TO_HOUR
• SQL_INTERVAL_MINUTE_TO_SECOND

The following table shows the ODBC C data types to which day-time interval SQL data may be converted. For an explanation of the columns and terms in the table, see Converting Data from SQL to C Data Types.

C type identifier	Test	*TargetValuePtr	*StrLen_or_IndPtr	SQLSTATE
All day-time C interval types	Trailing fields portion not truncated Trailing fields portion truncated Leading precision of target is not big enough to hold data from source	Data Truncated data Undefined	Length of data Length of data Undefined	n/a 01S07 22015
SQL_C_STINYINT[b] SQL_C_UTINYINT[b] SQL_C_USHORT[b] SQL_C_SHORT[b] SQL_C_SLONG[b] SQL_C_ULONG[b] SQL_C_NUMERIC[b] SQL_C_BIGINT[b]	Interval precision was a single field and the data was converted without truncation Interval precision was a single field and truncated fractional Interval precision was a single field and truncated whole Interval precision was not a single field	Data Truncated data Truncated data Undefined	Size of the C data type Length of data Length of data Size of the C data type	n/a 01S07 22003 07006
SQL_C_BINARY	Byte length of data <= BufferLength Byte length of data > BufferLength	Data Undefined	Length of data Undefined	n/a 22003
SQL_C_CHAR	Character byte length < BufferLength Number of whole (as opposed to fractional) digits < BufferLength Number of whole (as opposed to fractional) digits >= BufferLength	Data Truncated data Undefined	Size of the C data type Size of the C data type Undefined	n/a 01004 22003
SQL_C_WCHAR	Character length < BufferLength Number of whole (as opposed to fractional) digits < BufferLength Number of whole (as opposed to fractional) digits >= BufferLength	Data Truncated data Undefined	Size of the C data type Size of the C data type Undefined	n/a 01004 22003

[a] A day-time interval SQL type can be converted to any day-time interval C type.

[b] If the interval precision is a single field (one of DAY, HOUR, MINUTE, or SECOND), the interval SQL type can be converted to any exact numeric (SQL_C_STINYINT, SQL_C_UTINYINT, SQL_C_USHORT, SQL_C_SHORT, SQL_C_SLONG, SQL_C_ULONG, or SQL_C_NUMERIC).

The default conversion of an interval SQL type is to the corresponding C interval data type. The application then binds the column or parameter (or sets the SQL_DESC_DATA_PTR field in the appropriate record of the ARD) to point to the initialized SQL_INTERVAL_STRUCT structure (or passes a pointer to the SQL_ INTERVAL_STRUCT structure as the TargetValuePtr argument in a call to SQLGetData).

The following example demonstrates how to transfer data from a column of type SQL_INTERVAL_DAY_TO_MINUTE into the SQL_INTERVAL_STRUCT structure such that it comes back as a DAY_TO_HOUR interval.

SQL_INTERVAL_STRUCT is;  
SQLINTEGER    cbValue;  
SQLUINTEGER   days, hours;  
  
// Execute a select statement; "interval_column" is a column  
// whose data type is SQL_INTERVAL_DAY_TO_MINUTE.  
SQLExecDirect(hstmt, "SELECT interval_column FROM table", SQL_NTS);  
  
// Bind  
SQLBindCol(hstmt, 1, SQL_C_INTERVAL_DAY_TO_MINUTE, &is, sizeof(SQL_INTERVAL_STRUCT), &cbValue);  
  
// Fetch  
SQLFetch(hstmt);  
  
// Process data  
days = is.intval.day_second.day;  
hours = is.intval.day_second.hour;