Skip to content


PostgreSQL Types

SQLDelight column definitions are identical to regular PostgreSQL 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_smallint SMALLINT,               -- Retrieved as Short
  some_int2 INT2,                       -- Retrieved as Short
  some_integer INTEGER,                 -- Retrieved as Int
  some_int INT,                         -- Retrieved as Int
  some_int4 INT4,                       -- Retrieved as Int
  some_bigint BIGINT,                   -- Retrieved as Long
  some_int8 INT8,                       -- Retrieved as Long
  some_numeric NUMERIC,                 -- Retrieved as Double
  some_decimal DECIMAL,                 -- Retrieved as Double
  some_real REAL,                       -- Retrieved as Double
  some_float4 FLOAT4,                   -- Retrieved as Double
  some_double_prec DOUBLE PRECISION,    -- Retrieved as Double
  some_float8 FLOAT8,                   -- Retrieved as Double
  some_smallserial SMALLSERIAL,         -- Retrieved as Short
  some_serial2 SERIAL2,                 -- Retrieved as Short
  some_serial SERIAL,                   -- Retrieved as Int
  some_serial4 SERIAL4,                 -- Retrieved as Int
  some_bigserial BIGSERIAL,             -- Retrieved as Long
  some_serial8 SERIAL8,                 -- Retrieved as Long
  some_character CHARACTER,             -- Retrieved as String
  some_char CHAR,                       -- Retrieved as String
  some_char_var CHARACTER VARYING(16),  -- Retrieved as String
  some_varchar VARCHAR(16),             -- Retrieved as String
  some_text TEXT,                       -- Retrieved as String
  some_date DATE,                       -- Retrieved as String
  some_time TIME,                       -- Retrieved as String
  some_timestamp TIMESTAMP,             -- Retrieved as String
  some_json JSON                        -- Retrieved as String

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>;