How to delete all data in Oracle Database with SQL? - 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

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

Answer 4

You have two ways:
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;
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;