Can we delete data from parent table without deleting child table?

Can we delete data from parent table without deleting child table?

If you’re not able to set the “on delete cascade” or “on delete set null” attribute then you need to issue deletes against all the individual child tables.

How do you delete a row in a child table?

Two possible approaches.

1. If you have a foreign key, declare it as on-delete-cascade and delete the parent rows older than 30 days. All the child rows will be deleted automatically.
2. Based on your description, it looks like you know the parent rows that you want to delete and need to delete the corresponding child rows.

How do you delete all the row in the table without deleting the table?

To delete every row in a table:

1. Use the DELETE statement without specifying a WHERE clause. With segmented table spaces, deleting all rows of a table is very fast.
2. Use the TRUNCATE statement. The TRUNCATE statement can provide the following advantages over a DELETE statement:
3. Use the DROP TABLE statement.

What is the purpose on delete cascade deletes the dependent rows in the child table when a row in parent table is deleted?

Use the ON DELETE CASCADE option to specify whether you want rows deleted in a child table when corresponding rows are deleted in the parent table. If you do not specify cascading deletes, the default behavior of the database server prevents you from deleting data in a table if other tables reference it.

Can you delete a record for parent or child table?

ON DELETE CASCADE constraint is used in MySQL to delete the rows from the child table automatically, when the rows from the parent table are deleted.

Is deletion possible if the row to be deleted is referred in the child table?

Deletion is not possible if the row to be deleted is referred in the child table.

What is on delete restrict?

ON DELETE RESTRICT means you can’t delete a given parent row if a child row exists that references the value for that parent row.

Which SQL query is used to DELETE all rows in a table without deleting the table?

SQL Query to delete all rows in a table without deleting the table (structure, attributes, and indexes)

1. DELETE FROM table_name;
2. DELETE TABLE table_name;
3. DROP TABLE table_name;
4. NONE.

How to delete rows from child table in SQL?

The above will will also delete rows in the child table where (last_update_Dtm = sysdate-30) is false. TableA does not have a last_update_dtm column so there is no way of knowing which rows to delete without the entries in the child table. I could save the keys in the child table prior to deleting but this seems like an expensive approach.

Can you delete parent table without deleting child table?

Now,i like to delete the records of ‘A’ directly without deleting the child table one by one. Here,the problem is that out of those five child tables one or more can have also child tables.So,it is very difficult to go one by one and delete the all child tables followed by parent table.

Can you add a child table to a parent table?

Also,there is possibilities of adding one or more child table to any of those tables described above in later point of time.In that case my query which is developed at this moment will not work and i would get error of ”INTEGRITY CONSTRAINT VIOLATION”. also it can’t be modified right now.

What happens when you delete a table in SQL?

If you test the results of your SELECT statement to see what data set would be affected in a DELETE query, you’ll find that SELECT will return results for a list of multiple tables and against multiple subqueries where DELETE will not.