Application Note for QuNect ODBC for Quick Base

Scalar Type Conversion Function Supported by QuNect ODBC for Quick Base

Explicit data type conversion is specified in terms of SQL data type definitions.

The ODBC syntax for the explicit data type conversion function does not restrict conversions. The validity of specific conversions of one data type to another data type will be determined by each driver-specific implementation. The driver will, as it translates the ODBC syntax into the native syntax, reject those conversions that, although legal in the ODBC syntax, are not supported by the data source. The ODBC function SQLGetInfo, with the conversion options (such as SQL_CONVERT_BIGINT, SQL_CONVERT_BINARY, SQL_CONVERT_INTERVAL_YEAR_MONTH, and so on), provides a way to inquire about conversions supported by the data source.

The format of the CONVERT function is:

{fn CONVERT(value_exp, data_type)}

The function returns the value specified by value_exp converted to the specified data_type, where data_type is one of the following keywords:

SQL_BIGINT SQL_INTERVAL_HOUR_TO_MINUTE
SQL_BINARY SQL_INTERVAL_HOUR_TO_SECOND
SQL_BIT SQL_INTERVAL_MINUTE_TO_SECOND
SQL_CHAR SQL_LONGVARBINARY
SQL_DECIMAL SQL_LONGVARCHAR
SQL_DOUBLE SQL_NUMERIC
SQL_FLOAT SQL_REAL
SQL_GUID SQL_SMALLINT
SQL_INTEGER SQL_DATE
SQL_INTERVAL_MONTH SQL_TIME
SQL_INTERVAL_YEAR SQL_TIMESTAMP
SQL_INTERVAL_YEAR_TO_MONTH SQL_TINYINT
SQL_INTERVAL_DAY SQL_VARBINARY
SQL_INTERVAL_HOUR SQL_VARCHAR
SQL_INTERVAL_MINUTE SQL_WCHAR
SQL_INTERVAL_SECOND SQL_WLONGVARCHAR
SQL_INTERVAL_DAY_TO_HOUR SQL_WVARCHAR
SQL_INTERVAL_DAY_TO_MINUTE  
SQL_INTERVAL_DAY_TO_SECOND  

The ODBC syntax for the explicit data type conversion function does not support specification of conversion format. If specification of explicit formats is supported by the underlying data source, a driver must specify a default value or implement format specification.

The argument value_exp can be a column name, the result of another scalar function, or a numeric or string literal. For example:

{ fn CONVERT( { fn CURDATE() }, SQL_CHAR ) }

converts the output of the CURDATE scalar function to a character string.

Because ODBC does not mandate a data type for return values from scalar functions (because the functions are often data source–specific), applications should use the CONVERT scalar function whenever possible to force data type conversion.