Module jakarta.persistence
Package jakarta.persistence

Annotation Type MapKeyColumn

  • @Target({METHOD,FIELD})
@Retention(RUNTIME)
public @interface MapKeyColumn
    Specifies the mapping for the key column of a map whose map key is a basic type. If the name() element is not specified, it defaults to the concatenation of the following: the name of the referencing relationship field or property; "_"; "KEY".

    Example: {@snippet :

    Since:
    2.0

    • Optional Element Summary

      Optional Elements 
      Modifier and Type Optional Element Description
      java.lang.String columnDefinition
      (Optional) The SQL fragment that is used when generating the DDL for the column.
      boolean insertable
      (Optional) Whether the column is included in SQL INSERT statements generated by the persistence provider.
      int length
      (Optional) The column length.
      java.lang.String name
      (Optional) The name of the map key column.
      boolean nullable
      (Optional) Whether the database column is nullable.
      java.lang.String options
      (Optional) A SQL fragment appended to the generated DDL which declares this column.
      int precision
      (Optional) The precision for a column of SQL type decimal or numeric, or of similar database-native type.
      int scale
      (Optional) The scale for a column of SQL type decimal or numeric, or of similar database-native type.
      java.lang.String table
      (Optional) The name of the table that contains the column.
      boolean unique
      (Optional) Whether the column is a unique key.
      boolean updatable
      (Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.

    • Element Detail

      • name

        java.lang.String name
        (Optional) The name of the map key column. The table in which it is found depends upon the context.
        • If the map key is for an element collection, the map key column is in the collection table for the map value.
        • If the map key is for a ManyToMany entity relationship or for a OneToMany entity relationship using a join table, the map key column is in a join table.
        • If the map key is for a OneToMany entity relationship using a foreign key mapping strategy, the map key column is in the table of the entity that is the value of the map.

        Defaults to the concatenation of the following: the name of the referencing relationship field or property; "_"; "KEY".

        Default:
        ""

      • unique

        boolean unique
        (Optional) Whether the column is a unique key. This is a shortcut for the UniqueConstraint annotation at the table level and is useful for when the unique key constraint corresponds to only a single column. This constraint applies in addition to any constraint entailed by primary key mapping and to constraints specified at the table level.
        Default:
        false

      • nullable

        boolean nullable
        (Optional) Whether the database column is nullable.
        Default:
        false

      • insertable

        boolean insertable
        (Optional) Whether the column is included in SQL INSERT statements generated by the persistence provider.
        Default:
        true

      • updatable

        boolean updatable
        (Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.
        Default:
        true

      • columnDefinition

        java.lang.String columnDefinition
        (Optional) The SQL fragment that is used when generating the DDL for the column.

        Defaults to the generated SQL to create a column of the inferred type.

        Default:
        ""

      • options

        java.lang.String options
        (Optional) A SQL fragment appended to the generated DDL which declares this column. May not be used in conjunction with columnDefinition().
        Since:
        3.2
        Default:
        ""

      • table

        java.lang.String table
        (Optional) The name of the table that contains the column.

        Defaults: If the map key is for an element collection, the name of the collection table for the map value. If the map key is for a OneToMany or ManyToMany entity relationship using a join table, the name of the join table for the map. If the map key is for a OneToMany entity relationship using a foreign key mapping strategy, the name of the primary table of the entity that is the value of the map.

        Default:
        ""

      • length

        int length
        (Optional) The column length.

        Applies only to columns whose type is parameterized by length, for example, varchar or varbinary types.

        Default:
        255

      • precision

        int precision
        (Optional) The precision for a column of SQL type decimal or numeric, or of similar database-native type.

        Applies only to columns of exact numeric type.

        The default value 0 indicates that a provider-determined precision should be inferred.

        Default:
        0

      • scale

        int scale
        (Optional) The scale for a column of SQL type decimal or numeric, or of similar database-native type.

        Applies only to columns of exact numeric type.

        The default value 0 indicates that a provider-determined precision should be inferred.

        Default:
        0