Using Concise Functions

Some ODBC functions gain implicit access to descriptors. Application writers may find them more convenient than calling SQLSetDescField or SQLGetDescField. These functions are called concise functions because they perform a number of functions, including setting or getting descriptor fields. Some concise functions let an application set or retrieve several related descriptor fields in a single function call.

Concise functions can be called without first retrieving a descriptor handle for use as an argument. These functions work with the descriptor fields associated with the statement handle that they are called on.

The concise functions SQLBindCol and SQLBindParameter bind a column or parameter by setting the descriptor fields that correspond to their arguments. Each of these functions performs more tasks than simply setting descriptors. SQLBindCol and SQLBindParameter provide a complete specification of the binding of a data column or dynamic parameter. An application can, however, change individual details of a binding by calling SQLSetDescField or SQLSetDescRec, and can completely bind a column or parameter by making a series of suitable calls to these functions.

The concise functions SQLColAttribute, SQLDescribeCol, SQLDescribeParam, SQLNumParams, and SQLNumResultCols retrieve values in descriptor fields.

SQLSetDescRec and SQLGetDescRec are concise functions that with one call set or get multiple descriptor fields that affect the data type and storage of column or parameter data. SQLSetDescRec is an effective way to change the binding of column or parameter data in one step.

SQLSetStmtAttr and SQLGetStmtAttr serve as concise functions in some cases (see “Descriptor Fields” earlier in this chapter).