How do I drop a check constraint in SQL Server?

How do I drop a check constraint in SQL?

Drop a Check Constraint

The syntax for dropping a check constraint in SQL Server (Transact-SQL) is: ALTER TABLE table_name DROP CONSTRAINT constraint_name; table_name. The name of the table that you wish to drop the check constraint.

How do you drop constraints on a table?


  1. To explicitly drop unique constraints, use the DROP UNIQUE clause of the ALTER TABLE statement. …
  2. To drop primary key constraints, use the DROP PRIMARY KEY clause of the ALTER TABLE statement. …
  3. To drop (table) check constraints, use the DROP CHECK clause of the ALTER TABLE statement.

Can we drop a constraint?

To drop constraints, use the ALTER TABLE statement with the DROP or DROP CONSTRAINT clauses. This allows you to BIND and continue accessing the tables that contain the affected columns. The name of all unique constraints on a table can be found in the SYSCAT.

THIS IS IMPORTANT:  Frequent question: How do you automatically delete records in SQL Server after a certain amount of time?

How do you drop a table that contains referential constraints?

In SQL Server, you cannot drop a table if it is referenced by a FOREIGN KEY constraint. You have to either drop the child tables before removing the parent table, or remove foreign key constraints.

How do I drop a default constraint?

Syntax: ALTER TABLE <table_name> ALTER COLUMN <column_name> DROP DEFAULT; Example: Lets say we want to drop the constraint from STUDENTS table, which we have created in the above sections.

How do I drop a constraint without a name?

You can generate the command to drop the constraint and dynamically execute it, by using the code as follows:

  1. declare @schema_name nvarchar(256)
  2. declare @table_name nvarchar(256)
  3. declare @col_name nvarchar(256)
  4. declare @Command nvarchar(1000)
  5. set @schema_name = N’MySchema’
  6. set @table_name = N’Department’

How can I drop all constraints on a table in SQL Server?

Easy way is use sp_help tablename. All constraints will be listed. Then use ALTER TABLE DROP CONSTRAINT to drop them. Use EnterpriseManager to drop all constarints at once.

How do you drop multiple constraints?

To drop an existing constraint, specify the DROP CONSTRAINT keywords and the identifier of the constraint. To drop multiple constraints on the same table, the constraint names must be in comma-separated list that is delimited by parentheses. The constraint that you drop can have an ENABLED, DISABLED, or FILTERING mode.

What is drop constraint?

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

How do I drop a constraint in SQL Plus?

Drop Unique Constraint

The syntax for dropping a unique constraint in Oracle is: ALTER TABLE table_name DROP CONSTRAINT constraint_name; table_name. The name of the table to modify.

THIS IS IMPORTANT:  Your question: How install SQL Server Integration Services SSIS?

How do I drop a column constraint in SQL Server?

Using SQL Server Management Studio

In Object Explorer, expand the table with the check constraint. Expand Constraints. Right-click the constraint and click Delete. In the Delete Object dialog box, click OK.

How do you change constraints in SQL Server?

ALTER TABLE table_name MODIFY COLUMN column_name datatype; The basic syntax of an ALTER TABLE command to add a NOT NULL constraint to a column in a table is as follows. ALTER TABLE table_name MODIFY column_name datatype NOT NULL; The basic syntax of ALTER TABLE to ADD UNIQUE CONSTRAINT to a table is as follows.

Does drop column drop constraint?

The default drop option is CASCADE, which means any constraint that contains the column being dropped is also dropped. If a primary/unique key involving the column is referenced by other foreign key constraints, all referencing foreign keys are dropped.

How do you drop a table in SQL Server with Cascade constraints?

6 Answers. In SQL Server Management Studio, go to Options / SQL Server Object Explorer / Scripting, and enable ‘Generate script for dependent objects’. Then right click the table, script > drop to > new query window and it will generate it for you. Also works for dropping all objects in a db.

What does drop table cascade constraints do?

Specify CASCADE CONSTRAINTS to drop all referential integrity constraints that refer to primary and unique keys in the dropped table. If you omit this clause, and such referential integrity constraints exist, then the database returns an error and does not drop the table.

THIS IS IMPORTANT:  What is Substr in SQL?