Dynamic invocation of a select-statement
An application program can dynamically build a select-statement in the form of a character string placed in a host variable.
In general, the statement is built from some data available to the program (for example, a query obtained from a workstation). The statement so constructed can be prepared for execution by means of the (embedded) PREPARE statement, and referenced by a (non-executable) DECLARE CURSOR statement. The statement is then executed every time the cursor is opened by means of the (embedded) OPEN statement. After the cursor is open, the result table can be retrieved, one row at a time, by successive executions of the FETCH statement.
Used in this way, the select-statement must not contain references to host variables. It can contain parameter markers instead. The parameter markers are effectively replaced by the values of the host variables specified in the OPEN statement.