MySQLIntegrityConstraintViolationException

[snowfall]

I am getting the following error on inserting into my MySQL DBase.

My child table has a foreign key of the parent table. But while creating the table, i have used 'on delete cascade'.

I dnt know what the problem is. Pls help

com.mysql.jdbc.exceptions.MySQLIntegrityConstraint ViolationException: Cannot add
or update a child row: a foreign key constraint fails

[debasisdas]

This error occurs when you try to insert a duplicate value into a primay key or Unique constrained field.

Check to ensure that the value does not exist in database before inserting.

[snowfall]

This error occurs when you try to insert a duplicate value into a primay key or Unique constrained field.

Check to ensure that the value does not exist in database before inserting.

But i dnt have a primary key or unique key in my table. I have only Foreign Key

My table structure is

+---------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------------+-------------+------+-----+---------+-------+
| reply_no | int(5) | YES | | NULL | |
| question_no | int(5) | YES | MUL | NULL | |
| reply_content | text | YES | | NULL | |
| emp_name | varchar(40)| YES | | NULL | |
| emp_no | int(6) | YES | | NULL | |
| entry_dat | date | YES | | NULL | |
+---------------+-------------+------+-----+---------+-------+

pls help

[rpnew]

I am getting the following error on inserting into my MySQL DBase.

My child table has a foreign key of the parent table. But while creating the table, i have used 'on delete cascade'.

I dnt know what the problem is. Pls help

com.mysql.jdbc.exceptions.MySQLIntegrityConstraint ViolationException: Cannot add
or update a child row: a foreign key constraint fails

This error occurs when you are entering data into child table which is not there into parent table.

e.g.
I've PARENT table and CHILD table both contains one field say NAME.
Now NAME in CHILD is a foreign key which refers to the NAME in PARENT.
So if i insert anything in CHILD table's NAME field which is not there in PARENT table's NAME field than it will show this error. That is what foreign key constraint is there for.
To make it more clear lets take example with values...

Say Parent table contains two entries for NAME one is 'abc' and another is 'xyz'. So, if i'll try to insert anything besides these two values into child table's NAME column it will give me above mentioned error.

Regards,
RP

[snowfall]

If i delete a row in the child table with 'where condition of my foreign key', then does the table get corrupt??

Is that why i am getting this error??

[rpnew]

If i delete a row in the child table with 'where condition of my foreign key', then does the table get corrupt??

Is that why i am getting this error??

hi,
Are you deleting or adding(updating)...
cause this error comes when you are adding or updating child table column which has foreign key reference.

Regards,
RP

[debasisdas]

on delete cascade specifies if the parent data is deleted its dependent child record will also be deleted from the child table.

and the foreign key ensures that the parent record can't be deleted while there are some dependent child records in the child table.