Dynamic ESQL and the SQL Descriptor Area

Many Dynamic ESQL statements require a data structure (SQL descriptor area) to describe and exchange data between your application and the ESQL-LIB interface. This data structure takes the place of C variables declared for the same purpose in Static ESQL statements.

The C structure definition for this SQL descriptor area is contained in the proesql.h header file in your ESQL installation directory. It consists of a single SQLDA_T structure that includes an array of pointers to SQLVAR_T structures, one for each table column or parameter marker. You must declare a pointer to each SQL descriptor area to use. An SQL descriptor area is not bound to a particular SQL request, but is the mechanism by which data is exchanged. You can use a single SQL descriptor area to fetch values from one table and insert those values in another. For more information on the SQL descriptor area, see Programming with ESQL."


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