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      • First we write ALTER TABLE, then we list the name of the table (in our example: product), and next we add the clause ADD CONSTRAINT with the name of the UNIQUE constraint (in our example: UQ_product_name). This is followed by the UNIQUE keyword with column/columns (in our example it is column: name) in parentheses.
      learnsql.com/cookbook/how-to-make-a-column-unique-in-sql/

      How to Make a Column Unique in SQL? - LearnSQL.com

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  4. www.w3schools.com › sqL › sql_uniqueSQL UNIQUE Constraint - W3Schools

    To create a UNIQUE constraint on the "ID" column when the table is already created, use the following SQL: MySQL / SQL Server / Oracle / MS Access: ALTER TABLE Persons. ADD UNIQUE (ID); To name a UNIQUE constraint, and to define a UNIQUE constraint on multiple columns, use the following SQL syntax: MySQL / SQL Server / Oracle / MS Access:

  5. learnsql.com › how-to-make-a-column-unique-in-sqlHow to Make a Column Unique in SQL? - LearnSQL.com

    You would like to make a column unique in a given table in a database. Example: We would like to make the column name unique in the table product. The query below presents one way to do it. Solution 1: Creating new table with a UNIQUE constraint. CREATE TABLE product ( id INT NOT NULL PRIMARY KEY, name VARCHAR(100) UNIQUE, .

  6. learn.microsoft.com › en-us › sqlCreate unique constraints - SQL Server | Microsoft Learn

    Dec 20, 2023 · You can create a unique constraint in SQL Server by using SQL Server Management Studio or Transact-SQL to ensure no duplicate values are entered in specific columns that don't participate in a primary key.

  7. www.sqlservertutorial.net › sql-server-basics › sqlAn Essential Guide to SQL Server UNIQUE Constraint

    SQL Server UNIQUE constraints allow you to ensure that the data stored in a column, or a group of columns, is unique among the rows in a table. The following statement creates a table whose data in the email column is unique among the rows in the hr.persons table: CREATE SCHEMA hr; GO. CREATE TABLE hr.persons(

  8. database.guide › 4-ways-to-create-a-unique4 Ways to Create a UNIQUE Constraint in SQL Server

    Sep 13, 2024 · Let’s check out several ways to create a UNIQUE constraint in SQL Server. Option 1: Include it in the Column Definition. The most concise way to create a UNIQUE constraint when creating a table is to include it within the column definition: CREATE TABLE Employees (EmployeeID INT PRIMARY KEY, FirstName VARCHAR(50), LastName VARCHAR(50),

  9. stackoverflow.com › questions › 5181877How can I create a unique constraint on my column (SQL Server ...

    I have SQL Server 2008 R2 and I want to set a unique column. There seems to be two ways to do this: "unique index" and "unique constraint". They are not much different from what I understand, although unique constraint is recommended by most, because you also get an index automatically.

  10. www.sqlservertutorial.org › sql-server-uniqueSQL Server UNIQUE CONSTRAINT

    SQL Server UNIQUE CONSTRAINT. The objective of this SQL Server tutorial is to teach you how to use the UNIQUE CONSTRAINT to ensure the uniqueness of data in one or more columns in a table.