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MySQL Types

SQLDelight column definitions are identical to regular H2 column definitions but support an extra column constraint which specifies the Kotlin type of the column in the generated interface.

CREATE TABLE some_types (
  some_tiny_int TINYINT,                           -- Retrieved as Int
  some_small_int SMALLINT,                         -- Retrieved as Int
  some_integer INTEGER,                            -- Retrieved as Int
  some_int INT,                                    -- Retrieved as Int
  some_big_int BIGINT,                             -- Retrieved as Long
  some_decimal DECIMAL(6,5),                       -- Retrieved as Int
  some_dec DEC(6,5),                               -- Retrieved as Int
  some_numeric NUMERIC(6,5),                       -- Retrieved as Int
  some_float FLOAT(6),                             -- Retrieved as Double
  some_real REAL,                                  -- Retrieved as Double
  some_double DOUBLE,                              -- Retrieved as Double
  some_double_precision DOUBLE PRECISION,          -- Retrieved as Double
  some_boolean BOOLEAN,                            -- Retrieved as Boolean
  some_date DATE,                                  -- Retrieved as String
  some_time TIME,                                  -- Retrieved as String
  some_timestamp2 TIMESTAMP(6),                    -- Retrieved as String
  some_char CHAR,                                  -- Retrieved as String
  some_character CHARACTER(6),                     -- Retrieved as String
  some_char_varying CHAR VARYING(6),               -- Retrieved as String
  some_longvarchar LONGVARCHAR,                    -- Retrieved as String
  some_character_varying CHARACTER VARYING(6),     -- Retrieved as String
  some_varchar VARCHAR(16),                        -- Retrieved as String
  some_clo CHARACTER LARGE OBJECT(16),             -- Retrieved as String
  some_clob clob(16 M CHARACTERS),                 -- Retrieved as String
  some_binary BINARY,                              -- Retrieved as ByteArray
  some_binary2 BINARY(6),                          -- Retrieved as ByteArray
  some_longvarbinary LONGVARBINARY,                -- Retrieved as ByteArray
  some_longvarbinary2 LONGVARBINARY(6),            -- Retrieved as ByteArray
  some_binary_varying BINARY VARYING(6),           -- Retrieved as ByteArray
  some_varbinary VARBINARY(8),                     -- Retrieved as ByteArray
  some_uuid UUID,                                  -- Retrieved as ByteArray
  some_blob BLOB,                                  -- Retrieved as ByteArray
  some_blo BINARY LARGE OBJECT(6),                 -- Retrieved as ByteArray
  some_bit BIT,                                    -- Retrieved as ByteArray
  some_bit2 BIT(6),                                -- Retrieved as ByteArray
  some_bit_varying BIT VARYING(6),                 -- Retrieved as ByteArray
  some_interval INTERVAL YEAR TO MONTH,            -- Retrieved as ByteArray
  some_interval2 INTERVAL YEAR(3),                 -- Retrieved as ByteArray
  some_interval3 INTERVAL DAY(4) TO HOUR,          -- Retrieved as ByteArray
  some_interval4 INTERVAL MINUTE(4) TO SECOND(6),  -- Retrieved as ByteArray
  some_interval5 INTERVAL SECOND(4,6)              -- Retrieved as ByteArray

Custom Column Types

If you'd like to retrieve columns as custom types you can specify a Kotlin type:

import kotlin.collections.List;

CREATE TABLE hockeyPlayer (
  cup_wins TEXT AS List<String> NOT NULL

However, creating the Database will require you to provide a ColumnAdapter which knows how to map between the database type and your custom type:

val listOfStringsAdapter = object : ColumnAdapter<List<String>, String> {
  override fun decode(databaseValue: String) =
    if (databaseValue.isEmpty()) {
    } else {
  override fun encode(value: List<String>) = value.joinToString(separator = ",")

val queryWrapper: Database = Database(
  driver = driver,
  hockeyPlayerAdapter = hockeyPlayer.Adapter(
    cup_winsAdapter = listOfStringsAdapter


As a convenience the SQLDelight runtime includes a ColumnAdapter for storing an enum as String data.


CREATE TABLE hockeyPlayer (
  position TEXT AS HockeyPlayer.Position
val queryWrapper: Database = Database(
  driver = driver,
  hockeyPlayerAdapter = HockeyPlayer.Adapter(
    positionAdapter = EnumColumnAdapter()

Custom Types in Migrations

If migrations are the schema's source of truth, you can also specify the exposed kotlin type when altering a table:

import kotlin.collection.List;

ALTER TABLE my_table
  ADD COLUMN new_column VARCHAR(8) AS List<String>;