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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 )
The following SQL creates an index named "uidx_pid" on the "PersonID" column in the "Persons" table: CREATE UNIQUE INDEX uidx_pid. ON Persons (PersonID); Note: The syntax for creating indexes varies among different databases. Therefore: Check the syntax for creating indexes in your database.
5 Ιαν 2024 · The syntax for creating a UNIQUE INDEX involves the CREATE INDEX statement. Creating a UNIQUE INDEX on a Single Column: CREATE UNIQUE INDEX index_unique_column ON tbl_name (col_name); Creating a UNIQUE INDEX on Multiple Columns: CREATE UNIQUE INDEX index_unique_columns ON tbl_name (co1, col2, ...); Exmaples of MySQL Unique Index.
8 Ιαν 2022 · UNIQUE INDEX 'department_id_UNIQUE ('department_id' ASC) VISIBLE. This statement creates unique index on department_id column of employee table in your example. Index can be created during table creation as well as at later time after table is created.
MySQL allows you to use the CREATE UNIQUE INDEX statement to create a unique index. MySQL unique index syntax. To create a unique index, use the CREATE UNIQUE INDEX statement like this: CREATE UNIQUE INDEX index_name [USING {BTREE | HASH}] ON table_name (column_list) [algorithm_option | lock_option]; Explanation:
CREATE UNIQUE INDEX idx_student_id ON students(student_id); In this example: We create a students table with an id, student_id, name, and email. We then create a Unique Index on the student_id column. Now, let's try to insert some data: INSERT INTO students (student_id, name, email) VALUES ('S001', 'John Doe', 'john@example.com');
CREATE INDEX enables you to add indexes to existing tables. CREATE INDEX is mapped to an ALTER TABLE statement to create indexes. See Section 15.1.9, “ALTER TABLE Statement”. CREATE INDEX cannot be used to create a PRIMARY KEY; use ALTER TABLE instead. For more information about indexes, see Section 10.3.1, “How MySQL Uses Indexes”.
