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The DROP CONSTRAINT command is used to delete a UNIQUE, PRIMARY KEY, FOREIGN KEY, or CHECK constraint. DROP a UNIQUE Constraint. To drop a UNIQUE constraint, use the following SQL: SQL Server / Oracle / MS Access: ALTER TABLE Persons DROP CONSTRAINT UC_Person; MySQL: ALTER TABLE Persons DROP INDEX UC_Person; DROP a PRIMARY KEY Constraint.
18 wrz 2008 · Your syntax for dropping the FK doesn't need the words "foreign key". This is the syntax for MySQL, not SQL Server. You can replace it with the word "constraint".
To drop a primary key from a table, use an ALTER TABLE clause with the name of the table (in our example, product) followed by the clause DROP PRIMARY KEY. Since a table can have only one primary key, you don’t need to specify the primary key column(s).
29 sie 2023 · 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. This may be the clustered index of the table, causing the table to become a heap.
To delete a foreign key from a table, use the ALTER TABLE clause with the name of the table (in our example, student) followed by the clause DROP CONSTRAINT with the name of the foreign key constraint.
You can delete a foreign key constraint in SQL Server by using SQL Server Management Studio or Transact-SQL. Deleting a foreign key constraint removes the requirement to enforce referential integrity.
The DROP CONSTRAINT statement specifically deals with removing constraints other than the primary key. Syntax. The syntax for dropping a constraint in SQL Server is as follows: ALTER TABLE table_name DROP CONSTRAINT constraint_name;
