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Unique constraints

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

A candidate key that is not ideal for a Primary key should still be declared UNIQUE to enforce uniqueness, as well as for query performance reasons. In jOOQ, this can be done with the following approaches:

// Create a new table with columns and unnamed constraints
create.createTable("table")
      .column("column1", INTEGER)
      .column("column2", INTEGER)
      .column("column3", INTEGER)
      .unique("column1")
      .unique("column2", "column3")
      .execute();

// Equivalent to the above
create.createTable("table")
      .column("column1", INTEGER)
      .column("column2", INTEGER)
      .column("column3", INTEGER)
      .constraints(
          unique("column1"),
          unique("column2", "column3")
      )
      .execute();

// Create a new table with columns and named constraints (recommended if you want to alter the constraint)
create.createTable("table")
      .column("column1", INTEGER)
      .column("column2", INTEGER)
      .column("column3", INTEGER)
      .constraints(
          constraint("uk1").unique("column1"),
          constraint("uk2").unique("column2", "column3")
      )
      .execute();

Dialect support

This example using jOOQ:

createTable("table")
      .column("column1", INTEGER)
      .constraints(
          constraint("uk").unique("column1")
      )

Translates to the following dialect specific expressions:

-- ACCESS, DB2, FIREBIRD, HANA, TERADATA
CREATE TABLE table (
  column1 integer,
  CONSTRAINT uk
    UNIQUE (column1)
)

-- ASE, SYBASE
CREATE TABLE table (
  column1 int NULL,
  CONSTRAINT uk
    UNIQUE (column1)
)

-- AURORA_MYSQL, AURORA_POSTGRES, DERBY, EXASOL, H2, HSQLDB, MARIADB, MEMSQL, MYSQL, POSTGRES, REDSHIFT, SQLSERVER, VERTICA, 
-- YUGABYTEDB
CREATE TABLE table (
  column1 int,
  CONSTRAINT uk
    UNIQUE (column1)
)

-- BIGQUERY
CREATE TABLE table (
  column1 int64
)

-- COCKROACHDB
CREATE TABLE table (
  column1 int4,
  CONSTRAINT uk
    UNIQUE (column1)
)

-- INFORMIX
CREATE TABLE table (
  column1 integer,
  UNIQUE (column1) CONSTRAINT uk
)

-- ORACLE, SNOWFLAKE
CREATE TABLE table (
  column1 number(10),
  CONSTRAINT uk
    UNIQUE (column1)
)

-- SQLDATAWAREHOUSE
CREATE TABLE table (
  column1 int,
  CONSTRAINT uk
    UNIQUE (column1) NOT ENFORCED
)

-- SQLITE
CREATE TABLE "table" (
  column1 int,
  CONSTRAINT uk
    UNIQUE (column1)
)

(These are currently generated with jOOQ 3.18, see #10141), or translate your own on our website

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