diff --git a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/Expression.kt b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/Expression.kt
index c36f3d2..44ab21f 100644
--- a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/Expression.kt
+++ b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/Expression.kt
@@ -6,15 +6,15 @@ public interface Expression<RuntimeType, DatabaseType : ColumnType<RuntimeType>,
 	public interface Builder<OwnerBuilderUserExtension : Any> {
 		public fun <RuntimeType, DatabaseType : ColumnType<RuntimeType>> equals(
 			left: Expression<RuntimeType, DatabaseType, OwnerBuilderUserExtension>,
-			right: Expression<RuntimeType, DatabaseType, OwnerBuilderUserExtension>
+			right: Expression<RuntimeType, DatabaseType, OwnerBuilderUserExtension>,
 		): Expression<Boolean, ColumnType.BOOLEAN, OwnerBuilderUserExtension>
 
 		public fun isNull(
-			e: Expression<*, *, OwnerBuilderUserExtension>,
+			e: Expression<*, ColumnType.Nullable<*, *>, OwnerBuilderUserExtension>,
 		): Expression<Boolean, ColumnType.BOOLEAN, OwnerBuilderUserExtension>
 
 		public fun isNotNull(
-			e: Expression<*, *, OwnerBuilderUserExtension>,
+			e: Expression<*, ColumnType.Nullable<*, *>, OwnerBuilderUserExtension>,
 		): Expression<Boolean, ColumnType.BOOLEAN, OwnerBuilderUserExtension>
 	}
 }
\ No newline at end of file
diff --git a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/ddl/ColumnType.kt b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/ddl/ColumnType.kt
index 7caadad..e340724 100644
--- a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/ddl/ColumnType.kt
+++ b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/ddl/ColumnType.kt
@@ -1,141 +1,96 @@
 package ru.landgrafhomyak.serdha.api.v0.ddl
 
-import kotlin.jvm.JvmStatic
+import kotlin.jvm.JvmField
 import kotlinx.datetime.Instant
 import kotlinx.datetime.LocalDate
 import kotlinx.datetime.LocalDateTime
 import kotlinx.datetime.LocalTime
 
-@Suppress("ClassName")
-public abstract class ColumnType<RuntimeType> {
-	public abstract val typeName: String
+@OptIn(ExperimentalUnsignedTypes::class)
+@Suppress("ClassName", "RemoveRedundantQualifierName")
+public interface ColumnType<@Suppress("unused") RuntimeType> {
+	public val typeName: String
 
-	abstract override fun toString(): String
+	@Suppress("FunctionName", "PropertyName")
+	public interface Builder {
+		public fun <TableUserExtension : Any> ROW_ID(): ColumnType<RowId<TableUserExtension>>
 
-	public sealed class _StandardType<R> : ColumnType<R>() {
-		override fun toString(): String = "<serdha | column type '${this.typeName}'>"
+		public val BOOLEAN: ColumnType.BOOLEAN
+
+		public val INT_S8: ColumnType.INT_S8
+
+		public val INT_U8: ColumnType.INT_U8
+
+		public val INT_S16: ColumnType.INT_S16
+
+		public val INT_U16: ColumnType.INT_U16
+
+		public val INT_S32: ColumnType.INT_S32
+
+		public val INT_U32: ColumnType.INT_U32
+
+		public val INT_S64: ColumnType.INT_S64
+
+		public val INT_U64: ColumnType.INT_U64
+
+		public val LOCAL_DATE: ColumnType.LOCAL_DATE
+
+		public val LOCAL_TIME: ColumnType.LOCAL_TIME
+
+		public val LOCAL_DATETIME: ColumnType.LOCAL_DATETIME
+
+		public val INSTANT: ColumnType.INSTANT
+
+		public val FLOAT_32: ColumnType.FLOAT_32
+
+		public val FLOAT_64: ColumnType.FLOAT_64
+
+		public val STRING: ColumnType.STRING
+		public fun STRING(size: UInt): ColumnType.STRING
+
+		public val BYTE_ARRAY: ColumnType.BYTE_ARRAY
+		public fun BYTE_ARRAY(size: UInt): ColumnType.BYTE_ARRAY
+
+		public fun <R : Any, D : ColumnType<R>> nullableOf(d: D): Nullable<R, D>
 	}
 
-	public abstract class _VirtualType<R>(@Suppress("MemberVisibilityCanBePrivate") public val wraps: ColumnType<R>) {
-		override fun toString(): String = "<serdha | virtual column type '${this.wraps.typeName}'>"
-	}
+	public abstract class _VirtualType<R : Any>(@Suppress("MemberVisibilityCanBePrivate") @JvmField public val wraps: ColumnType<R>)
 
-	public class NULLABLE<RuntimeType : Any>(@Suppress("MemberVisibilityCanBePrivate") public val notNullType: ColumnType<RuntimeType>) : _StandardType<RuntimeType?>() {
-		init {
-			if (this.notNullType is NULLABLE<*>)
-				throw IllegalArgumentException("Type can't be nullable twice")
-		}
+	public interface Nullable<R : Any, @Suppress("unused") D : ColumnType<R>> : ColumnType<R?>
 
-		override val typeName: String = this.notNullType.typeName + "?"
-	}
+	public interface ROW_ID : ColumnType<RowId<*>>
 
-	public object ROW_ID : _StandardType<RowId<*>>() {
-		override val typeName: String get() = "ROW_ID"
-	}
+	public interface BOOLEAN : ColumnType<Boolean>
 
-	public object BOOLEAN : _StandardType<Boolean>() {
-		override val typeName: String get() = "BOOLEAN"
-	}
+	public interface INT_S8 : ColumnType<Byte>
 
-	public object INT_S8 : _StandardType<Byte>() {
-		override val typeName: String get() = "INT_S8"
-	}
+	public interface INT_U8 : ColumnType<UByte>
 
-	public object INT_U8 : _StandardType<UByte>() {
-		override val typeName: String get() = "INT_U8"
-	}
+	public interface INT_S16 : ColumnType<Short>
 
-	public object INT_S16 : _StandardType<Short>() {
-		override val typeName: String get() = "INT_S16"
-	}
+	public interface INT_U16 : ColumnType<UShort>
 
-	public object INT_U16 : _StandardType<UShort>() {
-		override val typeName: String get() = "INT_U16"
-	}
+	public interface INT_S32 : ColumnType<Int>
 
-	public object INT_S32 : _StandardType<Int>() {
-		override val typeName: String get() = "INT_S32"
-	}
+	public interface INT_U32 : ColumnType<UInt>
 
-	public object INT_U32 : _StandardType<UInt>() {
-		override val typeName: String get() = "INT_U32"
-	}
+	public interface INT_S64 : ColumnType<Long>
 
-	public object INT_S64 : _StandardType<Long>() {
-		override val typeName: String get() = "INT_S64"
-	}
+	public interface INT_U64 : ColumnType<ULong>
 
-	public object INT_U64 : _StandardType<ULong>() {
-		override val typeName: String get() = "INT_U64"
-	}
+	public interface LOCAL_DATE : ColumnType<LocalDate>
 
-	public object LOCAL_DATE : _StandardType<LocalDate>() {
-		override val typeName: String get() = "LOCAL_DATE"
-	}
+	public interface LOCAL_TIME : ColumnType<LocalTime>
 
-	public object LOCAL_TIME : _StandardType<LocalTime>() {
-		override val typeName: String get() = "LOCAL_TIME"
-	}
+	public interface LOCAL_DATETIME : ColumnType<LocalDateTime>
 
-	public object LOCAL_DATETIME : _StandardType<LocalDateTime>() {
-		override val typeName: String get() = "LOCAL_DATETIME"
-	}
+	public interface INSTANT : ColumnType<Instant>
 
-	public object INSTANT : _StandardType<Instant>() {
-		override val typeName: String get() = "INSTANT"
-	}
+	public interface FLOAT_32 : ColumnType<Float>
 
-	public object FLOAT_32 : _StandardType<Float>() {
-		override val typeName: String get() = "FLOAT_32"
-	}
+	public interface FLOAT_64 : ColumnType<Double>
 
-	public object FLOAT_64 : _StandardType<Float>() {
-		override val typeName: String get() = "FLOAT_64"
-	}
+	public interface STRING : ColumnType<String>
 
-	public class STRING internal constructor(
-		private val _size: UInt
-	) : _StandardType<String>() {
-		override val typeName: String = if (this._size == 0u) "STRING" else "STRING(${this._size})"
-
-		public val size: UInt? get() = if (this._size == 0u) null else this._size
-	}
-
-	public class BYTE_ARRAY internal constructor(
-		private val _size: UInt
-	) : _StandardType<String>() {
-		override val typeName: String = if (this._size == 0u) "BYTE_ARRAY" else "BYTE_ARRAY(${this._size})"
-
-		public val size: UInt? get() = if (this._size == 0u) null else this._size
-	}
-
-	public companion object DSL {
-		@Suppress("RemoveRedundantQualifierName")
-		@JvmStatic
-		public val STRING: STRING = ColumnType.STRING(0u)
-
-		@Suppress("RemoveRedundantQualifierName")
-		@JvmStatic
-		public fun STRING(size: UInt): STRING {
-			if (size == 0u)
-				throw IllegalArgumentException("Size of string can't be 0")
-			return ColumnType.STRING(size)
-		}
-
-		@Suppress("RemoveRedundantQualifierName")
-		@JvmStatic
-		public val BYTE_ARRAY: BYTE_ARRAY = ColumnType.BYTE_ARRAY(0u)
-
-		@Suppress("RemoveRedundantQualifierName")
-		@JvmStatic
-		public fun BYTE_ARRAY(size: UInt): BYTE_ARRAY {
-			if (size == 0u)
-				throw IllegalArgumentException("Size of byte array can't be 0")
-			return ColumnType.BYTE_ARRAY(size)
-		}
-
-		@Suppress("FunctionName", "UNCHECKED_CAST", "RemoveRedundantQualifierName")
-		@JvmStatic
-		public fun <T : Any> ROW_ID(): ColumnType<RowId<T>> = ColumnType.ROW_ID as ColumnType<RowId<T>>
-	}
+	public interface BYTE_ARRAY : ColumnType<UByteArray>
 }
diff --git a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/ddl/TableCreator.kt b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/ddl/TableCreator.kt
index 46f5a63..be4fd17 100644
--- a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/ddl/TableCreator.kt
+++ b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/ddl/TableCreator.kt
@@ -6,6 +6,8 @@ import ru.landgrafhomyak.serdha.api.v0.Expression
 public interface TableCreator<TableUserExtension : Any> {
 	public val expressionBuilder: Expression.Builder<TableUserExtension>
 
+	public val types: ColumnType.Builder
+
 	/**
 	 * Offers column of type [D][type] with `NOT NULL` constraint named [name] and runtime type [RuntimeType].
 	 *
@@ -27,7 +29,7 @@ public interface TableCreator<TableUserExtension : Any> {
 		toTable: Table<TargetTableUserWrapper, *>,
 		toColumn: Column<*, ColumnType1, TargetTableUserWrapper>,
 		onUpdate: ForeignKey.OnUpdateAction,
-		onDelete: ForeignKey.OnDeleteAction
+		onDelete: ForeignKey.OnDeleteAction,
 	): ForeignKey<TableUserExtension, TargetTableUserWrapper>
 
 	public fun <TargetTableUserWrapper : Any, ColumnType1 : ColumnType<*>, ColumnType2 : ColumnType<*>> foreignKey(
@@ -37,7 +39,7 @@ public interface TableCreator<TableUserExtension : Any> {
 		toColumn1: Column<*, ColumnType1, TargetTableUserWrapper>,
 		toColumn2: Column<*, ColumnType2, TargetTableUserWrapper>,
 		onUpdate: ForeignKey.OnUpdateAction,
-		onDelete: ForeignKey.OnDeleteAction
+		onDelete: ForeignKey.OnDeleteAction,
 	): ForeignKey<TableUserExtension, TargetTableUserWrapper>
 
 	public fun <TargetTableUserWrapper : Any, ColumnType1 : ColumnType<*>, ColumnType2 : ColumnType<*>, ColumnType3 : ColumnType<*>> foreignKey(
@@ -49,6 +51,6 @@ public interface TableCreator<TableUserExtension : Any> {
 		toColumn2: Column<*, ColumnType2, TargetTableUserWrapper>,
 		toColumn3: Column<*, ColumnType3, TargetTableUserWrapper>,
 		onUpdate: ForeignKey.OnUpdateAction,
-		onDelete: ForeignKey.OnDeleteAction
+		onDelete: ForeignKey.OnDeleteAction,
 	): ForeignKey<TableUserExtension, TargetTableUserWrapper>
 }
\ No newline at end of file
diff --git a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/dml/_CommonQueryMethods.kt b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/dml/_CommonQueryMethods.kt
index 07a2d6d..daac7a9 100644
--- a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/dml/_CommonQueryMethods.kt
+++ b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/dml/_CommonQueryMethods.kt
@@ -8,6 +8,8 @@ import ru.landgrafhomyak.serdha.api.v0.runtime.ParametersSetter
 
 @Suppress("ClassName")
 public interface _CommonQueryMethods<QueryUserExtension : Any> {
+	public val types: ColumnType.Builder
+
 	public fun <SelectedTableUserExtension : Any> selectTable(t: Table<SelectedTableUserExtension, *>): SelectedTable<SelectedTableUserExtension, QueryUserExtension>
 
 	public interface CanBeSubquery<@Suppress("unused") SelectedQueryUserExtension : Any>