DESCRIBE_COLUMNS Procedure

This procedure describes the columns for a cursor opened and parsed through DBMS_SQL.

The DESC_REC Type

The DBMS_SQL package declares the DESC_REC record type as follows:

type desc_rec is record (  
   col_type            BINARY_INTEGER := 0,
   col_max_len         BINARY_INTEGER := 0,
   col_name            VARCHAR2(32)   := '',
   col_name_len        BINARY_INTEGER := 0,
   col_schema_name     VARCHAR2(32)   := '',
   col_schema_name_len BINARY_INTEGER := 0,
   col_precision       BINARY_INTEGER := 0,
   col_scale           BINARY_INTEGER := 0,
   col_charsetid       BINARY_INTEGER := 0,
   col_charsetform     BINARY_INTEGER := 0,
   col_null_ok         BOOLEAN        := TRUE);

Parameters

Table 62-16 DESC_REC Type Parameters

Parameter	Description
col_type	Type of the column being described.
col_max_len	Maximum length of the column.
col_name	Name of the column.
col_name_len	Length of the column name.
col_schema_name	Name of the schema the column type was defined in, if an object type.
col_schema_name_len	Length of the schema.
col_precision	Column precision, if a number.
col_scale	Column scale, if a number.
col_charsetid	Column character set identifier.
col_charsetform	Column character set form.
col_null_ok	True if column can be null.

The DESC_TAB Type

The DESC_TAB type is a PL/SQL table of DESC_REC records:

type desc_tab is table of desc_rec index by BINARY_INTEGER;

You can declare a local variable as the PL/SQL table type DESC_TAB, and then call the DESCRIBE_COLUMNS procedure to fill in the table with the description of each column. All columns are described; you cannot describe a single column.

Syntax

DBMS_SQL.DESCRIBE_COLUMNS ( 
   c              IN  INTEGER, 
   col_cnt        OUT INTEGER, 
   desc_t         OUT DESC_TAB);

Parameters

Table 62-17 DBMS_SQL.DESCRIBE_COLUMNS Procedure Parameters

Parameter	Description
c	ID number of the cursor for the columns being described.
col_cnt	Number of columns in the select list of the query.
desc_t	Table of DESC_REC, each DESC_REC describing a column in the query.

See Also: "Example 8: Describe Columns" illustrates how to use DESCRIBE_COLUMNS.