Search results
Learn how to create a unique index on a table column to prevent duplicate values and speed up queries. See the syntax, examples and tips for different databases.
5 maj 2023 · This topic describes how to create a unique index on a table in SQL Server by using SQL Server Management Studio or Transact-SQL. A unique index guarantees that the index key contains no duplicate values and therefore every row in the table is in some way unique.
A view with a unique clustered index is called an indexed view. Creating a unique clustered index on a view physically materializes the view. A unique clustered index must be created on a view before any other indexes can be defined on the same view. For more information, see Create Indexed Views.
Learn how to create a unique index in SQL to enforce uniqueness on one or more columns in a table. See the syntax, examples and benefits of using unique indexes in SQL databases.
The basic syntax of the command to create a unique index is as follows. CREATE UNIQUE INDEX index_name ON table_name|view_name (column_list); In this syntax, UNIQUE – keyword which tells SQL Server to create the new index as a unique index. table_name|view_name –the name of the table or view on which the unique index is to be created.
To create a UNIQUE index, you use the CREATE UNIQUE INDEX statement as follows: CREATE UNIQUE INDEX index_name ON table_name(index_column_1,index_column_2,...); Code language: SQL (Structured Query Language) ( sql )
CREATE UNIQUE INDEX for Unique Values. If you want to create indexes for unique values in a column, we use the CREATE UNIQUE INDEX constraint. For example, -- create table CREATE TABLE Colleges ( college_id INT PRIMARY KEY, college_code VARCHAR(20) NOT NULL, college_name VARCHAR(50) );
