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ALTER TABLE .. ADD UNIQUE

Applies to ✅ Open Source Edition   ✅ Express Edition   ✅ Professional Edition   ✅ Enterprise Edition

All constraint types can be added with the ALTER TABLE statement. This includes UNIQUE constraints:

// Adding an unnamed constraint to a table
create.alterTable("table").add(unique("user_name")).execute();

// Adding a named constraint to a table
create.alterTable("table").add(constraint("uk").unique("user_name")).execute();
It is recommended to always provide a name with a constraint to simplify schema management. See also this section of the manual

Dialect support

This example using jOOQ:

alterTable("t").add(constraint("uk").unique("user_name"))

Translates to the following dialect specific expressions:

ASE, Access, Aurora MySQL, Aurora Postgres, BigQuery, ClickHouse, CockroachDB, DB2, Derby, Exasol, Firebird, H2, HSQLDB, Hana, MariaDB, MemSQL, MySQL, Oracle, Postgres, Redshift, SQLServer, Snowflake, Sybase, Teradata, Vertica, YugabyteDB

ALTER TABLE t ADD CONSTRAINT uk UNIQUE (user_name)

Informix

ALTER TABLE t ADD CONSTRAINT UNIQUE (user_name) CONSTRAINT uk

SQLDataWarehouse

ALTER TABLE t ADD CONSTRAINT uk UNIQUE (user_name) NOT ENFORCED

DuckDB, SQLite, Trino

/* UNSUPPORTED */
Generated with jOOQ 3.20. Translate your own SQL on our website

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