Table types

In Exposed, the Table class is the core abstraction for defining database tables. This class provides methods to define various column types, constraints, and other table-specific properties.

Table is located in the org.jetbrains.exposed.sql package of the exposed-core module.

The following example defines a table with an auto-incrementing integer id column and string name and director column:

import org.jetbrains.exposed.sql.Table

const val MAX_VARCHAR_LENGTH = 50

object StarWarsFilmsTable : Table() {
    val id = integer("id").autoIncrement()
    val sequelId = integer("sequel_id").uniqueIndex()
    val name = varchar("name", MAX_VARCHAR_LENGTH)
    val director = varchar("director", MAX_VARCHAR_LENGTH)
}

     CREATE TABLE IF NOT EXISTS STARWARSFILMS
     (ID INT AUTO_INCREMENT NOT NULL,
      SEQUEL_ID INT NOT NULL,
      "name" VARCHAR(50) NOT NULL,
      DIRECTOR VARCHAR(50) NOT NULL)

For more information on defining and configuring tables in Exposed, see Working with tables.

While Table is the foundational class for defining tables in DSL, you can also use the IdTable subclasses from the DAO API for convenience. For example, to provide an auto-incrementing id column of type Int, you can use the IntIdTable subtype:

object StarWarsFilmsTable : IntIdTable() {
    val sequelId = integer("sequel_id").uniqueIndex()
    val name = varchar("name", MAX_VARCHAR_LENGTH)
    val director = varchar("director", MAX_VARCHAR_LENGTH)
}

It is important to note that the id column in this case is of type Column<EntityID<Int>>. The EntityID wrapper ensures that the id values are handled consistently across the DSL and DAO APIs.

To access the id column value, you need to use the .value property:

val movieId: Int = movie.id.value

For more information on IdTable, see the DAO documentation.

Last modified: 05 December 2024