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Dialects

Overview

Dialects absorb differences in databases and drivers. A typical function of dialects is to resolve the type mappings between Kotlin and SQL.

The classes representing dialects are contained in separate modules (artifacts), and the choice of which module to use must be based on the destination database and connectivity type.

Database	Type	Artifact ID	Dialect Class
H2 Database Engine	JDBC	komapper-dialect-h2-jdbc	H2JdbcSqlDialect
H2 Database Engine	R2DBC	komapper-dialect-h2-r2dbc	H2R2dbcSqlDialect
MariaDB	JDBC	komapper-dialect-mariadb-jdbc	MariaDbJdbcDialect
MariaDB	R2DBC	komapper-dialect-mariadb-r2dbc	MariaDbR2dbcDialect
MySQL	JDBC	komapper-dialect-mysql-jdbc	MySqlJdbcDialect
MySQL	R2DBC	komapper-dialect-mysql-r2dbc	MySqlR2dbcDialect
Oracle Database	JDBC	komapper-dialect-oracle-jdbc	OracleJdbcDialect
Oracle Database	R2DBC	komapper-dialect-oracle-r2dbc	OracleR2dbcDialect
PostgreSQL	JDBC	komapper-dialect-postgresql-jdbc	PostgreSqlJdbcDialect
PostgreSQL	R2DBC	komapper-dialect-postgresql-r2dbc	PostgreSqlR2dbcDialect
SQL Server	JDBC	komapper-dialect-sqlserver-jdbc	SqlServerJdbcDialect
SQL Server	R2DBC	komapper-dialect-sqlserver-r2dbc	SqlServerR2dbcDialect

To use a dialect, specify the Artifact ID above in the Gradle dependencies declaration.

val komapperVersion: String by project
dependencies {
    implementation("org.komapper:komapper-dialect-h2-jdbc:$komapperVersion")
}

H2 - JDBC

The following table shows the data type mapping:

Kotlin Type	SQL Type	Description
java.math.BigDecimal	NUMERIC
java.math.BigInteger	NUMERIC
java.sql.Array	ARRAY
java.sql.Blob	BLOB
java.sql.Clob	CLOB
java.sql.NClob	CLOB
java.sql.SQLXML	CLOB
java.time.Instant	TIMESTAMP WITH TIME ZONE
java.time.LocalDate	DATE
java.time.LocalDateTime	TIMESTAMP
java.time.LocalTime	TIME
java.time.OffsetDateTime	TIMESTAMP WITH TIME ZONE
java.util.UUID	UUID
kotlin.Any	JAVA_OBJECT
kotlin.Boolean	BOOLEAN
kotlin.Byte	TINYINT
kotlin.ByteArray	BINARY
kotlin.Double	DOUBLE
kotlin.Float	REAL
kotlin.Int	INT
kotlin.Long	BIGINT
kotlin.Short	SMALLINT
kotlin.String	VARCHAR
kotlin.String	CLOB	`ClobString` must be specified as alternate type.
kotlin.UByte	SMALLINT
kotlin.UInt	BIGINT
kotlin.UShort	INT
kotlinx.datetime.Instant	TIMESTAMP WITH TIME ZONE
kotlinx.datetime.LocalDate	DATE
kotlinx.datetime.LocalDateTime	TIMESTAMP
enum class	VARCHAR	Can be customized by @KomapperEnum or komapper.enumStrategy.

H2 - R2DBC

The following table shows the data type mapping:

Kotlin Type	SQL Type	Description
io.r2dbc.spi.Blob	BLOB
io.r2dbc.spi.Clob	CLOB
java.math.BigDecimal	NUMERIC
java.math.BigInteger	NUMERIC
java.time.Instant	TIMESTAMP WITH TIME ZONE
java.time.LocalDate	DATE
java.time.LocalDateTime	TIMESTAMP
java.time.LocalTime	TIME
java.time.OffsetDateTime	TIMESTAMP WITH TIME ZONE
java.util.UUID	UUID
kotlin.Any	N/A
kotlin.Boolean	BOOLEAN
kotlin.Byte	TINYINT
kotlin.ByteArray	BINARY
kotlin.Double	DOUBLE
kotlin.Float	REAL
kotlin.Int	INT
kotlin.Long	BIGINT
kotlin.Short	SMALLINT
kotlin.String	VARCHAR
kotlin.String	CLOB	`ClobString` must be specified as alternate type.
kotlin.UByte	SMALLINT
kotlin.UInt	BIGINT
kotlin.UShort	INT
kotlinx.datetime.Instant	TIMESTAMP WITH TIME ZONE
kotlinx.datetime.LocalDate	DATE
kotlinx.datetime.LocalDateTime	TIMESTAMP
enum class	VARCHAR	Can be customized by @KomapperEnum or komapper.enumStrategy.

MariaDB - JDBC

The following table shows the data type mapping:

Kotlin Type	SQL Type	Description
java.math.BigDecimal	DECIMAL
java.math.BigInteger	DECIMAL
java.sql.Array	N/A
java.sql.Blob	BLOB
java.sql.Clob	TEXT
java.sql.NClob	TEXT
java.sql.SQLXML	TEXT
java.time.Instant	TIMESTAMP
java.time.LocalDate	DATE
java.time.LocalDateTime	DATETIME
java.time.LocalTime	TIME
java.time.OffsetDateTime	TIMESTAMP
java.util.UUID	N/A
kotlin.Any	N/A
kotlin.Boolean	BIT(1), BOOLEAN
kotlin.Byte	TINYINT
kotlin.ByteArray	VARBINARY
kotlin.Double	DOUBLE
kotlin.Float	FLOAT
kotlin.Int	INT
kotlin.Long	BIGINT
kotlin.Short	SMALLINT
kotlin.String	VARCHAR
kotlin.String	TEXT	`ClobString` must be specified as alternate type.
kotlin.UByte	SMALLINT
kotlin.UInt	BIGINT
kotlin.UShort	INT
kotlinx.datetime.Instant	TIMESTAMP
kotlinx.datetime.LocalDate	DATE
kotlinx.datetime.LocalDateTime	DATETIME
enum class	VARCHAR	Can be customized by @KomapperEnum or komapper.enumStrategy.

MariaDB - R2DBC

The following table shows the data type mapping:

Kotlin Type	SQL Type	Description
io.r2dbc.spi.Blob	BLOB
io.r2dbc.spi.Clob	TEXT
java.math.BigDecimal	DECIMAL
java.math.BigInteger	DECIMAL
java.time.Instant	TIMESTAMP
java.time.LocalDate	DATE
java.time.LocalDateTime	DATETIME
java.time.LocalTime	TIME
java.time.OffsetDateTime	TIMESTAMP
java.util.UUID	N/A
kotlin.Any	N/A
kotlin.Boolean	BIT(1), BOOLEAN
kotlin.Byte	TINYINT
kotlin.ByteArray	VARBINARY
kotlin.Double	DOUBLE
kotlin.Float	FLOAT
kotlin.Int	INT
kotlin.Long	BIGINT
kotlin.Short	SMALLINT
kotlin.String	VARCHAR
kotlin.String	TEXT	`ClobString` must be specified as alternate type.
kotlin.UByte	SMALLINT
kotlin.UInt	BIGINT
kotlin.UShort	INT
kotlinx.datetime.Instant	TIMESTAMP
kotlinx.datetime.LocalDate	DATE
kotlinx.datetime.LocalDateTime	DATETIME
enum class	VARCHAR	Can be customized by @KomapperEnum or komapper.enumStrategy.

MySQL - JDBC

The following table shows the data type mapping:

Kotlin Type	SQL Type	Description
java.math.BigDecimal	DECIMAL
java.math.BigInteger	DECIMAL
java.sql.Array	N/A
java.sql.Blob	BLOB
java.sql.Clob	TEXT
java.sql.NClob	TEXT
java.sql.SQLXML	TEXT
java.time.Instant	TIMESTAMP
java.time.LocalDate	DATE
java.time.LocalDateTime	DATETIME
java.time.LocalTime	TIME
java.time.OffsetDateTime	TIMESTAMP
java.util.UUID	N/A
kotlin.Any	N/A
kotlin.Boolean	BIT(1), BOOLEAN
kotlin.Byte	TINYINT
kotlin.ByteArray	VARBINARY
kotlin.Double	DOUBLE
kotlin.Float	FLOAT
kotlin.Int	INT
kotlin.Long	BIGINT
kotlin.Short	SMALLINT
kotlin.String	VARCHAR
kotlin.String	TEXT	`ClobString` must be specified as alternate type.
kotlin.UByte	SMALLINT
kotlin.UInt	BIGINT
kotlin.UShort	INT
kotlinx.datetime.Instant	TIMESTAMP
kotlinx.datetime.LocalDate	DATE
kotlinx.datetime.LocalDateTime	DATETIME
enum class	VARCHAR	Can be customized by @KomapperEnum or komapper.enumStrategy.

MySQL - R2DBC

The following table shows the data type mapping:

Kotlin Type	SQL Type	Description
io.r2dbc.spi.Blob	N/A
io.r2dbc.spi.Clob	N/A
java.math.BigDecimal	DECIMAL
java.math.BigInteger	DECIMAL
java.time.Instant	TIMESTAMP
java.time.LocalDate	DATE
java.time.LocalDateTime	DATETIME
java.time.LocalTime	N/A
java.time.OffsetDateTime	TIMESTAMP
java.util.UUID	N/A
kotlin.Any	N/A
kotlin.Boolean	BIT(1), BOOLEAN
kotlin.Byte	TINYINT
kotlin.ByteArray	VARBINARY
kotlin.Double	DOUBLE
kotlin.Float	FLOAT
kotlin.Int	INT
kotlin.Long	BIGINT
kotlin.Short	SMALLINT
kotlin.String	VARCHAR
kotlin.String	TEXT	`ClobString` must be specified as alternate type.
kotlin.UByte	SMALLINT
kotlin.UInt	BIGINT
kotlin.UShort	INT
kotlinx.datetime.Instant	TIMESTAMP
kotlinx.datetime.LocalDate	DATE
kotlinx.datetime.LocalDateTime	DATETIME
enum class	VARCHAR	Can be customized by @KomapperEnum or komapper.enumStrategy.

Oracle - JDBC

The following table shows the data type mapping:

Kotlin Type	SQL Type	Description
java.math.BigDecimal	NUMBER
java.math.BigInteger	NUMBER
java.sql.Array	N/A
java.sql.Blob	BLOB
java.sql.Clob	CLOB
java.sql.NClob	N/A
java.sql.SQLXML	N/A
java.time.Instant	TIMESTAMP WITH TIME ZONE
java.time.LocalDate	DATE
java.time.LocalDateTime	TIMESTAMP
java.time.LocalTime	TIME
java.time.OffsetDateTime	TIMESTAMP WITH TIME ZONE
java.util.UUID	N/A
kotlin.Any	N/A
kotlin.Boolean	NUMBER
kotlin.Byte	NUMBER
kotlin.ByteArray	RAW
kotlin.Double	FLOAT
kotlin.Float	FLOAT
kotlin.Int	NUMBER
kotlin.Long	NUMBER
kotlin.Short	NUMBER
kotlin.String	VARCHAR2
kotlin.String	CLOB	`ClobString` must be specified as alternate type.
kotlin.UByte	NUMBER
kotlin.UInt	NUMBER
kotlin.UShort	NUMBER
kotlinx.datetime.Instant	TIMESTAMP WITH TIME ZONE
kotlinx.datetime.LocalDate	DATE
kotlinx.datetime.LocalDateTime	TIMESTAMP
enum class	VARCHAR2	Can be customized by @KomapperEnum or komapper.enumStrategy.

Oracle - R2DBC

The following table shows the data type mapping:

Kotlin Type	SQL Type	Description
io.r2dbc.spi.Blob	BLOB
io.r2dbc.spi.Clob	CLOB
java.math.BigDecimal	NUMBER
java.math.BigInteger	NUMBER
java.time.Duration	INTERVAL DAY TO SECOND
java.time.Instant	TIMESTAMP WITH TIME ZONE
java.time.LocalDate	DATE
java.time.LocalDateTime	TIMESTAMP
java.time.LocalTime	TIME
java.time.Period	INTERVAL YEAR TO MONTH
java.time.OffsetDateTime	TIMESTAMP WITH TIME ZONE
java.util.UUID	N/A
kotlin.Any	N/A
kotlin.Boolean	NUMBER
kotlin.Byte	NUMBER
kotlin.ByteArray	RAW
kotlin.Double	FLOAT
kotlin.Float	FLOAT
kotlin.Int	NUMBER
kotlin.Long	NUMBER
kotlin.Short	NUMBER
kotlin.String	VARCHAR2
kotlin.String	CLOB	`ClobString` must be specified as alternate type.
kotlin.UByte	NUMBER
kotlin.UInt	NUMBER
kotlin.UShort	NUMBER
kotlinx.datetime.Instant	TIMESTAMP WITH TIME ZONE
kotlinx.datetime.LocalDate	DATE
kotlinx.datetime.LocalDateTime	TIMESTAMP
enum class	VARCHAR2	Can be customized by @KomapperEnum or komapper.enumStrategy.

PostgreSQL - JDBC

The following table shows the data type mapping:

Kotlin Type	SQL Type	Description
java.math.BigDecimal	numeric, decimal
java.math.BigInteger	numeric, decimal
java.sql.Array	array of data type
java.sql.Blob	N/A
java.sql.Clob	N/A
java.sql.NClob	N/A
java.sql.SQLXML	xml
java.time.Instant	timestamp with time zone
java.time.LocalDate	date
java.time.LocalDateTime	timestamp
java.time.LocalTime	time
java.time.OffsetDateTime	timestamp with time zone
java.util.UUID	uuid
kotlin.Any	N/A
kotlin.Boolean	boolean, bool
kotlin.Byte	smallint
kotlin.ByteArray	bytea
kotlin.Double	double precision, float8
kotlin.Float	real
kotlin.Int	integer, int, int4, serial
kotlin.Long	bigint, int8, bigserial, serial8
kotlin.Short	smallint, int2, smallserial, serial2
kotlin.String	character varying, varchar, text
kotlin.String	text	`ClobString` must be specified as alternate type.
kotlin.UByte	smallint, int2, smallserial, serial2
kotlin.UInt	bigint, int8, bigserial, serial8
kotlin.UShort	integer, int, int4, serial
kotlinx.datetime.Instant	timestamp with time zone
kotlinx.datetime.LocalDate	date
kotlinx.datetime.LocalDateTime	timestamp
enum class	character varying, varchar, text	Can be customized by @KomapperEnum or komapper.enumStrategy.

PostgreSQL - R2DBC

The following table shows the data type mapping:

Kotlin Type	SQL Type	Description
io.r2dbc.postgresql.codec.Interval	interval
io.r2dbc.postgresql.codec.Json	json, jsonb
io.r2dbc.spi.Blob	bytea
io.r2dbc.spi.Clob	text
java.math.BigDecimal	numeric, decimal
java.math.BigInteger	numeric, decimal
java.time.Instant	timestamp with time zone
java.time.LocalDate	date
java.time.LocalDateTime	timestamp
java.time.LocalTime	time
java.time.OffsetDateTime	timestamp with time zone
java.util.UUID	uuid
kotlin.Any	N/A
kotlin.Array	array of data type
kotlin.Boolean	boolean, bool
kotlin.Byte	smallint
kotlin.ByteArray	bytea
kotlin.Double	double precision, float8
kotlin.Float	real
kotlin.Int	integer, int, int4, serial
kotlin.Long	bigint, int8, bigserial, serial8
kotlin.Short	smallint, int2, smallserial, serial2
kotlin.String	character varying, varchar, text
kotlin.String	text	`ClobString` must be specified as alternate type.
kotlin.UByte	smallint, int2, smallserial, serial2
kotlin.UInt	bigint, int8, bigserial, serial8
kotlin.UShort	integer, int, int4, serial
kotlinx.datetime.Instant	timestamp with time zone
kotlinx.datetime.LocalDate	date
kotlinx.datetime.LocalDateTime	timestamp
enum class	character varying, varchar, text	Can be customized by @KomapperEnum or komapper.enumStrategy.

SQL Server - JDBC

The following table shows the data type mapping:

Kotlin Type	SQL Type	Description
java.math.BigDecimal	decimal
java.math.BigInteger	decimal
java.sql.Array	N/A
java.sql.Blob	varbinary(max)
java.sql.Clob	text
java.sql.NClob	N/A
java.sql.SQLXML	xml
java.time.Instant	datetimeoffset
java.time.LocalDate	date
java.time.LocalDateTime	datetime2
java.time.LocalTime	time
java.time.OffsetDateTime	datetimeoffset
java.util.UUID	N/A
kotlin.Any	N/A
kotlin.Boolean	bit
kotlin.Byte	smallint, tinyint
kotlin.ByteArray	varbinary
kotlin.Double	float
kotlin.Float	real
kotlin.Int	int
kotlin.Long	bigint
kotlin.Short	smallint
kotlin.String	varchar, nvarchar
kotlin.String	text	`ClobString` must be specified as alternate type.
kotlin.UByte	smallint
kotlin.UInt	bigint
kotlin.UShort	int
kotlinx.datetime.Instant	datetimeoffset
kotlinx.datetime.LocalDate	date
kotlinx.datetime.LocalDateTime	datetime2
enum class	varchar, nvarchar	Can be customized by @KomapperEnum or komapper.enumStrategy.

SQL Server - R2DBC

The following table shows the data type mapping:

Kotlin Type	SQL Type	Description
io.r2dbc.spi.Blob	varbinary(max)
io.r2dbc.spi.Clob	text
java.math.BigDecimal	decimal
java.math.BigInteger	decimal
java.time.Instant	datetimeoffset
java.time.LocalDate	date
java.time.LocalDateTime	datetime2
java.time.LocalTime	time
java.time.OffsetDateTime	N/A
java.util.UUID	N/A
kotlin.Any	N/A
kotlin.Boolean	bit
kotlin.Byte	smallint, tinyint
kotlin.ByteArray	varbinary
kotlin.Double	float
kotlin.Float	real
kotlin.Int	int
kotlin.Long	bigint
kotlin.Short	smallint
kotlin.String	varchar, nvarchar
kotlin.String	text	`ClobString` must be specified as alternate type.
kotlin.UByte	smallint
kotlin.UInt	bigint
kotlin.UShort	int
kotlinx.datetime.Instant	datetimeoffset
kotlinx.datetime.LocalDate	date
kotlinx.datetime.LocalDateTime	datetimev
enum class	varchar, nvarchar	Can be customized by @KomapperEnum or komapper.enumStrategy.

Last modified February 5, 2023: Add the description about enum mapping (452cac2)