Oracle determines whether a field exists before deleting a field

Oracle determines whether a field exists before deleting a field

If you delete a non-existent field in the table in Oracle, such as "alter table test drop column xxx", the following message is displayed:

ORA-00904: "xxx": Invalid identifier

If this statement is executed in the program, an exception is reported. Therefore, we need to determine whether the field exists before deleting it. If yes, delete it.

DECLARE num NUMBER; begin select count (1) INTO num from cols where table_name = upper ('tablename') and column_name = upper ('columnname '); IF num> 0 THEN execute immediate 'alter table tableName drop column columnname'; end if; END;