Does dropping a table drop the index?

Does dropping a table drop the index?

DROP TABLE always removes any indexes, rules, triggers, and constraints that exist for the target table.

Can we dropped for constraints?

PRIMARY KEY constraints can be dropped with DROP CONSTRAINT if an ADD CONSTRAINT statement follows the DROP CONSTRAINT statement in the same transaction. Tip: When you change a primary key with ALTER TABLE ... ALTER PRIMARY KEY , the old primary key index becomes a secondary index.

Which constraint prevents drop table from dropping a table?

FOREIGN KEY constraint If you drop the "child" table first, the foreign key will be dropped as well. If you attempt to drop the "parent" table first, you will get an "Could not drop object 'a' because it is referenced by a FOREIGN KEY constraint." error. If it is SQL Server you must drop the constraint before you can drop the table.

How do I drop a table with constraints in SQL?

Constraints are dropped using the ALTER TABLE command:

1. ALTER TABLE … DROP CONSTRAINT … explicitly drops the specified constraint. Similar to modifying constraints, the constraint can be identified by the constraint name or column definition along with the constraint type. ...
2. ALTER TABLE … DROP COLUMN …

Do I need to drop index before dropping table?

3 Answers. Yes, it does. However, if you have foreign key constraints such as RESTRICT that ensure referential integrity with other tables, you'll want to drop those keys prior to dropping or truncating a table. Yes it would drop the index.

What are dropped automatically when table dropped?

The SQL DROP command is used to remove an object (table,view,index) from the database. When you drop a table, all the rows from the table will be deleted with the structure from the database. ... When a table is dropped, by default all the constraints or triggers associated with the table will be deleted automatically.

What is drop constraint?

The DROP CONSTRAINT command is used to delete a UNIQUE, PRIMARY KEY, FOREIGN KEY, or CHECK constraint.

Can we drop primary key constraint?

You cannot drop a primary key constraint if another table has a foreign key constraint that references the primary key. To drop the primary key, you must first drop all foreign keys that reference it.

How do you drop a table that contains referential constraints?

To drop foreign key (referential) constraints, use the DROP CONSTRAINT clause of the ALTER TABLE statement. When a foreign key constraint is dropped, packages or cached dynamic statements containing the following might be marked as invalid: Statements that insert or update the table containing the foreign key.

Can primary key be deleted?

You can delete (drop) a primary key in SQL Server by using SQL Server Management Studio or Transact-SQL. When the primary key is deleted, the corresponding index is deleted.

What happens if we drop a constraint?

• If you drop the constraint the data currently stored in the table is not changed but of course following DML operations can add values out of the check constraint's range - and also NULL values if there is no additional NOT NULL constraint. There are not many situations where droping or disabling a constraint is a good idea.

How to create table constraints?

• and click Design.
• Keys.
• click Add.
• and then click Close.

How does dropping column affect constraints?

• If the column is part of a multiple-column primary-key or unique constraint, the constraints placed on the multiple columns are also dropped. This action, in turn, triggers the dropping of all referential constraints that reference the multiple columns. Because any constraints that are associated with a column are dropped when the column is dropped, the structure of other tables might also be altered when you use this clause.

How can we drop unique constraint from a mySQL table?

• Drop Unique Constraint. The syntax for dropping a unique constraint in MySQL is: ALTER TABLE table_name DROP INDEX constraint_name; table_name The name of the table to modify. This is the table that you wish to remove the unique constraint from. constraint_name The name of the unique constraint to remove. Example