How to test if a column exists in a table

Question

Hello,
Using SQL or PL/SQL how do I test if a column exists in a table. For example,
if column_aa exists in table_1
then do this....
else do that....
Thank you.

Answer 1

Set ServerOutput On;
CREATE Table a_Test (
Col1 NUMBER
, Col2 NUMBER )
DECLARE
lnCol1 NUMBER ;
lnCol7 NUMBER ;
PROCEDURE TestColumn( acColName IN VARCHAR2 )
IS
lnColX NUMBER ;
NoColumnExists EXCEPTION;
PRAGMA EXCEPTION_INIT(NoColumnExists, -904);
BEGIN
EXECUTE IMMEDIATE
'SELECT Max('|| acColName||') FROM a_Test WHERE RowNum = 0'
INTO lnColX ;
DBMS_OUTPUT.Put_Line('Column: '||acColName||' exists.');
EXCEPTION
WHEN NoColumnExists THEN
DBMS_OUTPUT.Put_Line('Column: '||acColName||' NOT exists.');
WHEN Others THEN
DBMS_OUTPUT.Put_Line( SqlCode ||' '||SqlErrM );
END
BEGIN
DBMS_OUTPUT.Enable ;
TestColumn( 'Col1') ;
TestColumn( 'Col2') ;
TestColumn( 'Col7') ;
END
DROP Table a_Test;