類型

PostgreSQL 類型

SQLDelight 的欄位定義與常規 PostgreSQL 欄位定義相同，但支援一項 額外的欄位約束，該約束用於指定生成介面中欄位的 Kotlin 類型。

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 BigDecimal
  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 LocalDate
  some_time TIME,                       -- Retrieved as LocalTime
  some_timestamp TIMESTAMP,             -- Retrieved as LocalDateTime
  some_timestamp TIMESTAMPTZ,           -- Retrieved as OffsetDateTime
  some_json JSON,                       -- Retrieved as String
  some_jsonb JSONB,                     -- Retrieved as String
  some_interval INTERVAL,               -- Retrieved as String
  some_uuid UUID                        -- Retrieved as UUID
  some_bool BOOL,                       -- Retrieved as Boolean
  some_boolean BOOLEAN,                 -- Retrieved as Boolean
  some_bytea BYTEA                      -- Retrieved as ByteArray
);

自訂欄位型別

如果您想將欄位擷取為自訂型別，可以指定一個 Kotlin 型別：

import kotlin.String;
import kotlin.collections.List;

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

然而，建立 Database 將需要您提供一個 ColumnAdapter，它知道如何將資料庫型別映射到您的自訂型別：

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

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

列舉 (Enums)

為方便起見，SQLDelight 執行時 (runtime) 包含一個 ColumnAdapter，用於將列舉 (enum) 儲存為字串資料。

import com.example.hockey.HockeyPlayer;

CREATE TABLE hockeyPlayer (
  position TEXT AS HockeyPlayer.Position
)

val queryWrapper: Database = Database(
  driver = driver,
  hockeyPlayerAdapter = HockeyPlayer.Adapter(
    positionAdapter = EnumColumnAdapter()
  )
)

值型別

如果需要，SQLDelight 可以為欄位生成一個值型別，該型別會包裝底層 (underlying) 資料庫型別：

CREATE TABLE hockeyPlayer (
  id INT AS VALUE
);

## 樂觀鎖定

如果將欄位指定為 `LOCK`，它會為其產生一個值型別，並要求 `UPDATE` 陳述式正確使用該鎖定來執行更新。

```sql
CREATE TABLE hockeyPlayer(
  id INT AS VALUE,
  version_number INT AS LOCK,
  name VARCHAR(8)
);

-- 這將會失敗（IDE 外掛會建議改寫成下面的形式）
updateName:
UPDATE hockeyPlayer
SET name = ?;

-- 這將會通過編譯
updateNamePassing:
UPDATE hockeyPlayer
SET name = ?
    version_number = :version_number + 1
WHERE version_number = :version_number;

遷移中的自訂型別

如果遷移是綱要 (schema) 的事實來源，您也可以在修改表格時指定公開的 Kotlin 型別：

import kotlin.String;
import kotlin.collection.List;

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