DESCRIBE statement

Use the DESCRIBE statement to obtain information about output parameters and other features of a prepared object before you execute it.

Use this statement with . (See also DESCRIBE INPUT statement.)

Syntax


Element	Description	Restrictions	Syntax
descriptor	Name of a system-descriptor area	System-descriptor area must already be allocated	Quoted String
descriptor_var	Host variable specifying a system-descriptor area	Must contain the name of an allocated system-descriptor area	Language-specific rules for names
sqlda_pointer	Pointer to an sqlda structure	Cannot begin with dollar ( $ ) sign or colon ( : ). An sqlda structure is required if dynamic SQL is used.	See the sqlda structure in the HCL OneDB™ ESQL/C Programmer's Manual
statement_id	Statement identifier for a prepared SQL statement	Must be defined in a previous PREPARE statement	PREPARE statement; Identifier
statement _id_var	Host variable that contains the value of statement_id	Must be declared in a previous PREPARE statement	Language-specific rules for names

DESCRIBE can provide information at runtime about a prepared statement:

The type of SQL statement that was prepared
Whether an UPDATE or DELETE statement contains a WHERE clause
For an EXECUTE, EXECUTE FUNCTION, EXECUTE PROCEDURE, INSERT, SELECT, or UPDATE statement, the DESCRIBE statement also returns the number, data types, and size of the output parameter values.
For a SELECT statement, DESCRIBE also returns the name of the column or expression that the query returns.

With this information, you can write code to allocate memory to hold retrieved values and display or process them after they are fetched.