This topic provides information about ODBC and SQL-92 scalar functions.
Because functions are often data-source-specific, ODBC does not require a data type for return values from scalar functions. To force data type conversion, applications should use the CONVERT scalar function.
Note:
ODBC and SQL-92 classify functions in different ways. ODBC classifies scalar functions by argument type, whereas SQL-92 classifies them by return value. For example, in ODBC, the EXTRACT function is classified as a timedate function because the extract-field argument is a timedate keyword and the extract_source argument is a timedate or interval expression. In SQL-92, however, the EXTRACT function is classified as a numeric scalar function because the return value is numeric.
Applications need to call SQLGetInfo to determine which scalar functions a driver supports. ODBC and SQL-92 information types are available for scalar function classifications. Because ODBC and SQL-92 use different classifications, the information types for the same function may differ between ODBC and SQL-92. For example, to determine support for the EXTRACT function requires SQL_TIMEDATE_FUNCTIONS information type in ODBC and SQL_SQL92_NUMERIC_VALUE_FUNCTIONS information type in SQL-92.