COLUMN_PRESENT Function

This function is meant to be used in conjunction with DBMS_LOGMNR.MINE_VALUE.

The syntax for this function is as follows:

Syntax

dbms_logmnr.column_present(
     sql_redo_undo        IN  RAW,
     column_name        IN  VARCHAR2 default '') RETURN NUMBER;

Parameters

The parameters for the COLUMN_PRESENT function are listed in Table 24-6.

Table 24-6 COLUMN_PRESENT Function Parameters

Parameter	Description
sql_redo_undo	Value of the REDO_VALUE or UNDO_VALUE columns selected from V$LOGMNR_CONTENTS. The value of this parameter directs LogMiner to look for undo or redo column information.
column_name	Fully qualified column name which this function will return information about.

Returns

Table 24-7 Return Values for COLUMN_PRESENT Function

Return	Description
0	Specified column is not present in this row of V$LOGMNR_CONTENTS.
1	Column is present in this row of V$LOGMNR_CONTENTS. Returns 1 if the self-describing record (the first parameter) contains the column specified in the second parameter. This can be used to distinguish between NULL returns from the DBMS_LOGMNR.MINE_VALUE function.

Exceptions

No LogMiner errors are returned.

Usage Notes

• To use the COLUMN_PRESENT function, you must have successfully started a LogMiner session.

• The COLUMN_PRESENT function must be invoked in the context of a select operation from the V$LOGMNR_CONTENTS view.

• The COLUMN_PRESENT function does not support LONG, LOB, ADT, or COLLECTION datatypes.