How to delete all data in Oracle Database with SQL?

Question

I had created a lot of tables and users while testing some SQL command and now I dont remember exactly all the tables and user's name.

But now I want to delete all of it for my big project.So is it possible to delete it in SQL command line ?

Answer 1

This PL/SQL block will be useful to delete all the data in oracle data base

BEGIN
   FOR cur_rec IN (SELECT object_name, object_type
                     FROM user_objects
                    WHERE object_type IN
                             ('TABLE',
                              'VIEW',
                              'PACKAGE',
                              'PROCEDURE',
                              'FUNCTION',
                              'SEQUENCE',
                              'SYNONYM',
                              'PACKAGE BODY'
                             ))
   LOOP
      BEGIN
         IF cur_rec.object_type = 'TABLE'
         THEN
            EXECUTE IMMEDIATE    'DROP '
                              || cur_rec.object_type
                              || ' "'
                              || cur_rec.object_name
                              || '" CASCADE CONSTRAINTS';
         ELSE
            EXECUTE IMMEDIATE    'DROP '
                              || cur_rec.object_type
                              || ' "'
                              || cur_rec.object_name
                              || '"';
         END IF;
      EXCEPTION
         WHEN OTHERS
         THEN
            DBMS_OUTPUT.put_line (   'FAILED: DROP '
                                  || cur_rec.object_type
                                  || ' "'
                                  || cur_rec.object_name
                                  || '"'
                                 );
      END;
   END LOOP;
END;

/

Answer 2

execute this command:

BEGIN
   FOR table_ IN (SELECT * FROM dba_tables where owner like 'YOUR_SCHEMA') LOOP
       execute immediate 'truncate table ' || table_.owner || '.' || table_.table_name ||' cascade';
   END LOOP;
END;
/

Answer 3

You have two ways:

1. you can use function delete instead truncate for this function you should not disable constraints, but it work more slowly because you can rollback this operation if you will go this way:

    BEGIN FOR table_ IN (SELECT * FROM dba_tables where owner like 'YOUR_SCHEMA') LOOP execute immediate 'delete from table ' || table_.owner || '.' || table_.table_name; END LOOP; END;

2. use truncate it is more faster, but you must diable constraints on table:

    begin for disable_constraint_ in (select * from dba_constraints where owner= 'YOUR_SCHEMA' ) loop execute immediate 'alter table ' || disable_constraint_.owner || '.' || disable_constraint_.table_name ||' disable constraint '|| disable_constraint_.constraint_name; end loop; for table_ in (select * from dba_tables where owner = 'YOUR_SCHEMA') loop execute immediate 'truncate table ' || table_.owner || '.' ||table_.table_name ||' cascade'; end loop; for enable_constaint_ in (select * from dba_constraints where owner= 'YOUR_SCHEMA') loop execute immediate 'alter table ' || enable_constaint_.owner || '.' || enable_constaint_.table_name ||' enable constraint '|| enable_constaint_.constraint_name; end loop; end;

Answer 4

   BEGIN

        FOR T in (SELECT table_name FROM user_tables) LOOP
          EXECUTE IMMEDIATE 'ALTER TABLE '||T.table_name||' DISABLE ALL CONSTRAINTS';
          --This will disable all the constraint  
        END LOOP;


        FOR T in (SELECT table_name FROM user_tables) LOOP
          EXECUTE IMMEDIATE 'TRUNCATE TABLE '||T.table_name;
        END LOOP;

        FOR T in (SELECT table_name FROM user_tables) LOOP
          EXECUTE IMMEDIATE 'ALTER TABLE '||T.table_name||' ENABLE ALL CONSTRAINTS';
        END LOOP;
    END;

Alter table ... disable all constraints throws a ORA-01735: invalid ALTER TABLE option if there is no constraint defined for the table, which would cause the script to fail to truncate every table if there is at least one table without constraint. You might want to place the execute immediate within a begin -exception block