EN
MySQL - make column values unique
0 points
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:
xxxxxxxxxx1
ALTER TABLE `table_name` 2
ADD UNIQUE (`column_name`);or:
xxxxxxxxxx1
ALTER TABLE `table_name`2
ADD CONSTRAINT `constraint_name` UNIQUE (`column_name`);or:
xxxxxxxxxx1
ALTER TABLE `table_name`2
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:
xxxxxxxxxx1
ALTER TABLE `users`2
ADD CONSTRAINT `UC_username` UNIQUE (`name`);Result:
Using query
xxxxxxxxxx1
SHOW INDEXES FROM `users`;
Using HeidiSQL
In this example, we will make name and country columns unique.
Query:
xxxxxxxxxx1
ALTER TABLE `users`2
ADD CONSTRAINT `UC_user` UNIQUE (`name`, `country`);Result:
Using query
xxxxxxxxxx1
SHOW INDEXES FROM `users`;
Using HeidiSQL:
