Dialect

Different databases have vastly different SQL support, so Jimmer uses dialect configuration to adapt to different databases.

Set Dialect

• If using the Spring Boot Starter provided by Jimmer, there are two ways:

  • Configure application.yml or application.properties

    jimmer:
    dialect: org.babyfish.jimmer.sql.dialect.MySqlDialect

  • Provide global dialect Bean

    Java

    @Bean
    public Dialect dialect() {
        return new MySqlDialect(); 
    }

    Kotlin

    @Bean
    fun dialect(): Dialect =
        MySqlDialect()
    info

    If both methods above are used (not recommended), the second method takes precedence

• If not using the Spring Boot Starter provided by Jimmer

  Java

  JSqlClient sqlClient = JSqlClient
      .newBuilder()
      .setDialect(new MySqlDialect())
      ...Omit other configurations...
      .build();

  Kotlin

  val sqlClient = newKSqlClient {
      setDialect(MySqlDialect())
      ...Omit other configurations...
  }

Dialect List

• org.babyfish.jimmer.sql.dialect.DefaultDialect

  This is the default dialect used by Jimmer when no dialect is specified, so there is no need to specify it explicitly.

  warning

  The default configuration can only be used for learning simple demos in the initial stage, and can never be used in actual projects. The following situations will cause exceptions:

  • Operations on Jimmer in the code will generate SQL that depends on specific database products, rather than perfect cross-database SQL

  • When the type of trigger is set to TRANSACTION_ONLY and cache is used, Jimmer will automatically create the JIMMER_TRANS_CACHE_OPERATOR table at startup. DefaultDialect does not support this operation, please refer to Cache Consistency

• org.babyfish.jimmer.sql.dialect.H2Dialect

• org.babyfish.jimmer.sql.dialect.MySqlDialect

• org.babyfish.jimmer.sql.dialect.PostgresDialect

• org.babyfish.jimmer.sql.dialect.OracleDialect

• org.babyfish.jimmer.sql.dialect.TiDBDialect

  Because TiDB is a distributed database that does not support foreign key constraints, true foreign keys are not supported by this dialect. Please refer to True and False Foreign Keys

  Apart from this, TiDBDialect has no difference with MySqlDialect.

• For other databases, users can extend dialects by themselves. But the database needs to support multi-column in expressions, such as

  where (a, b) in ((3, 4), (8, 13)) 

  Or

  where (a, b) in (select x, y from ...)
  note

  Currently, multi-column in expressions are highly dependent features of Jimmer, and Microsoft Sql Server does not support this feature for the time being.

  So Microsoft Sql Server is not supported for now.