The only index keyword in mysql is

The unique index keyword is UNIQUE, which is used to ensure that the specified column or column combination in the table has a unique value. The benefits of creating a unique index include: data integrity, query performance optimization, and unique constraint enforcement.

The unique index keyword in MySQL

In MySQL, the keyword used to create a unique index isUNIQUE.

What is a unique index?

A unique index is a special type of index that ensures that a specific column or combination of columns is unique in each record in a table. In other words, it does not allow duplicate values ​​in the table.

Why use unique index?

Using a unique index has the following benefits:

• Ensure data integrity: Prevent duplicate values ​​from appearing in the same column or combination of columns.
• Optimize query performance: Unique indexes can speed up queries based on corresponding columns because it can quickly find the required records.
• Implement unique constraints: Unique indexes can enforce unique constraints by prohibiting duplicate values.

How to create a unique index?

The following SQL statement demonstrates how to create a unique index:

<code class="sql">CREATE UNIQUE INDEX index_name ON table_name (column_name1, column_name2, ...);</code>

For example, the following statement is between name and ## of the customers table #email Create a unique index on the column:

<code class="sql">CREATE UNIQUE INDEX unique_name_email ON customers (name, email);</code>

Note:

Each table can have up to 16 unique indexes.
• Unique indexes can be applied to multiple columns to form a composite unique index.
• MySQL will throw an error if you try to insert a record into a table that contains duplicate values.

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