MySQL Unique Index: How to Create One

In MySQL, you can use the CREATE INDEX statement to create a unique index. A unique index is an index where each index value can only appear once, used to ensure that each record in the table has a unique value in the indexed column.

Here is an example syntax for creating a unique index:

CREATE UNIQUE INDEX index_name
ON table_name (column_name);

The index_name refers to the name of the index, table_name indicates the table where the index will be created, and column_name specifies the column for which a unique index will be created.

For example, to create a unique index in a table named example_table, you can use the following statement:

CREATE UNIQUE INDEX unique_index
ON example_table (column_name);

Please note that when creating a unique index, if duplicate values are present, the index will not be created and an error message will be returned.