GET DESCRIPTOR statement

Use the GET DESCRIPTOR statement to read from a system descriptor area.

Syntax

(1)
Described Item Information

1  field_var  = 
2.1 DATA
2.1 IDATA
2.1 ILENGTH
2.1 INDICATOR
2.1 ITYPE
2.1 LENGTH
2.1 NAME
2.1 NULLABLE
2.1 PRECISION
2.1 SCALE
2.1 TYPE
1 1
2.1 EXTYPEID
2.1 EXTYPELENGTH
2.1 EXTYPENAME
2.1 EXTYPEOWNERLENGTH
2.1 EXTYPEOWNERNAME
2.1 SOURCEID
2.1 SOURCETYPE
Notes:
  • 1 HCL OneDB™ extension

Element Description Restrictions Syntax
descriptor Quoted string that identifies a system-descriptor area (SDA) System-descriptor area must already have been allocated Quoted String
descriptor_var Variable that stores descriptor value Same restrictions as descriptor Language specific
field_var Host variable to receive the contents of a field from an SDA Must be of type that can receive value of a specified SDA field Language specific
item_num Unsigned ordinal number of an item described in the SDA 0 < item_num < (number of item descriptors in the SDA) Literal Number
item_num_ var Host variable storing item_num Must be an integer data type Language specific
total_items_var Host variable storing the number of items described in the SDA Must be an integer data type Language specific

Usage

Use this statement with .

Use the GET DESCRIPTOR statement to accomplish any of the following tasks:
  • Determine how many items are described in a system-descriptor area.
  • Determine the characteristics of each column or expression that is described in the system-descriptor area.
  • Copy a value from the system-descriptor area into a host variable after a FETCH statement.

You can use GET DESCRIPTOR after you describe EXECUTE FUNCTION, INSERT, SELECT, or UPDATE statements with the DESCRIBE . . . USING SQL DESCRIPTOR statement.

The host variables that you reference in the GET DESCRIPTOR statement must be declared in the BEGIN DECLARE SECTION of a program.

If an error occurs during the assignment of a value to any specified host variable, the contents of the host variable are undefined.

Examples

The following ESQL/C example shows how to use a GET DESCRIPTOR statement with a host variable to determine how many items are described in the system-descriptor area called desc1: GET DESCRIPTOR 
main() 
{ 
	EXEC SQL BEGIN DECLARE SECTION; 
		int h_count; 
	EXEC SQL END DECLARE SECTION; 

	EXEC SQL allocate descriptor 'desc1' with max 20; 
	
	/* This section of program would prepare a SELECT or INSERT 
	* statement into the s_id statement id. 
	*/ 

	EXEC SQL describe s_id using sql descriptor 'desc1'; 
	EXEC SQL get descriptor 'desc1' :h_count = count;
The following ESQL/C example uses GET DESCRIPTOR to obtain data type information from the demodesc system-descriptor area: 
EXEC SQL get descriptor 'demodesc' value 
	:index :type = TYPE, 
	:len = LENGTH, 
	:name = NAME; 
printf("Column %d: type = %d, len = %d, name = %s\n", 
	index, type, len, name);
The following ESQL/C example shows how you can copy data from the DATA field into a host variable (result) after a fetch. For this example, it is predetermined that all returned values are the same data type: 
EXEC SQL get descriptor 'demodesc' :desc_count = count; 
.. . 
EXEC SQL fetch democursor using sql descriptor 'demodesc'; 
for (i = 1; i <= desc_count; i++) 
	{ 
	if (sqlca.sqlcode != 0) break; 
	EXEC SQL get descriptor 'demodesc' value :i :result = DATA; 
	printf("%s ", result); 
} 
printf("\n");