EN
MySQL - make column values unique
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In this article, we would like to show you how to make column values unique in MySQL.
In MySQL we can create unique constraint for single or multiple columns.
Quick solution:
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ALTER TABLE `table_name`
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ADD UNIQUE (`column_name`);
or:
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ALTER TABLE `table_name`
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ADD CONSTRAINT `constraint_name` UNIQUE (`column_name`);
or:
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ALTER TABLE `table_name`
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ADD CONSTRAINT `constraint_name` UNIQUE (`column1`, `column2`, `columnN`);
To show how to make column values unique, we will use the following table:

In this example, we will make name
column unique.
Query:
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ALTER TABLE `users`
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ADD CONSTRAINT `UC_username` UNIQUE (`name`);
Result:
Using query
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SHOW INDEXES FROM `users`;

Using HeidiSQL

In this example, we will make name
and country
columns unique.
Query:
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ALTER TABLE `users`
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ADD CONSTRAINT `UC_user` UNIQUE (`name`, `country`);
Result:
Using query
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SHOW INDEXES FROM `users`;

Using HeidiSQL:
