constraint unique sql
ALTER TABLE table_name ADD CONSTRAINT cst_name UNIQUE (col_name);
ALTER TABLE table_name ADD CONSTRAINT cst_name UNIQUE (col1, col2); -- Multiple
ALTER TABLE table_name ADD col_name NUMBER UNIQUE; -- New fieldconstraint unique sql
ALTER TABLE table_name ADD CONSTRAINT cst_name UNIQUE (col_name);
ALTER TABLE table_name ADD CONSTRAINT cst_name UNIQUE (col1, col2); -- Multiple
ALTER TABLE table_name ADD col_name NUMBER UNIQUE; -- New fieldhow to drop a unique constraint in sql
SHOW CREATE TABLE [tableName]
-- Find the constraintID after CONSTRAINT 'constraintID'
ALTER TABLE [tableName] DROP FOREIGN KEY constraintIDunique constraint mssql
USE AdventureWorks2012;
GO
CREATE TABLE Production.TransactionHistoryArchive4
(
TransactionID int NOT NULL,
CONSTRAINT AK_TransactionID UNIQUE(TransactionID)
);
GOunique key in sql
Unique Key:
Only unique value and also can contain NULLCopyright © 2021 Codeinu
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