1.Alter table
this query will convert table into innoDB
2. Consider two tables
1.parent
| id | name |
| 1 | kites |
| id | address |
| 1 | cochin |
alter table child add foreign key (id) references parent(id) on delete cascade.
If you set a foreign key with on delete cascade then
1.first tou want to insert data into parent then to child.
2.You can delete record from child independently but you can't insert into child without corresponing record in parent.
3.If you delete a record from parent table it will delete from both parent and child table without any warning.
Eg: if you try to delete a record from parent with id 1 it will also delete the record from child whose id=1
4.set the foreign key with on delete restrict
alter table child add foreign key (id) references parent(id) on delete restrict.
If you set a foreign key with on delete restrict then
1.first you want to insert data into parent then to child.
2.You can delete record from child independently but you can't insert into child without corresponing record in parent.
3.It will restrict deletion from parent tables if a corresponding child record is available.
4.I f you want to delete from parent table then you want to delete record from child table first