The SQL Descriptor Area (SQLDA)
The SQLDA is unique to each precompiler. For example, the Oracle SQLDA is not compatible with that used by DB2 or OpenESQL.
When either the number of parameters to be passed, or their data types, are unknown at compilation time, you can use an SQL Descriptor Area (SQLDA) instead of host variables.
An SQLDA contains descriptive information about each input parameter or output column. It contains the column name, data type, length, and a pointer to the actual data buffer for each input or output parameter. An SQLDA is ordinarily used with parameter markers to specify input values for prepared SQL statements but you can also use an SQLDA with the DESCRIBE statement (or the INTO option of a PREPARE statement) to receive data from a prepared SELECT statement.
Although you cannot use an SQLDA with static SQL statements, you can use a SQLDA with a cursor FETCH statement.