diff --git a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/queries/SelectQuery.kt b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/queries/SelectQuery.kt
index 0d01f97..6a6232b 100644
--- a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/queries/SelectQuery.kt
+++ b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/queries/SelectQuery.kt
@@ -1,5 +1,6 @@
 package ru.landgrafhomyak.serdha.api.v0.queries
 
+import ru.landgrafhomyak.serdha.api.v0.misc.BuiltinExpressionsProvider
 import ru.landgrafhomyak.serdha.api.v0.misc.Column
 import ru.landgrafhomyak.serdha.api.v0.misc.IntermediateColumn
 import ru.landgrafhomyak.serdha.api.v0.misc.DatabaseType
@@ -19,6 +20,7 @@ public interface SelectQuery<QueryUserExtension : Any> : _Query<QueryUserExtensi
 		public fun <RT, DT : DatabaseType<RT>> queryParam(name: String, type: DT): QueryParam<RT, DT, QueryUserExtension>
 		public fun <RT, DT : DatabaseType<RT>> paramAsColumn(param: QueryParam<RT, DT, QueryUserExtension>): IntermediateColumn<RT, DT, QueryUserExtension>
 
+		public val builtinExpressions: BuiltinExpressionsProvider<QueryUserExtension>
 		public fun <ExpressionUserExtension : Any> mapColumns(
 			expression: Expression<ExpressionUserExtension>,
 			input: Expression.InputLinker<ExpressionUserExtension, QueryUserExtension>,
diff --git a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/CheckConstraint.kt b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/CheckConstraint.kt
index bc7238e..bceb8f1 100644
--- a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/CheckConstraint.kt
+++ b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/CheckConstraint.kt
@@ -1,43 +1,39 @@
 package ru.landgrafhomyak.serdha.api.v0.table
 
 import kotlin.jvm.JvmName
+import ru.landgrafhomyak.serdha.api.v0.misc.BuiltinExpressionsProvider
 import ru.landgrafhomyak.serdha.api.v0.misc.Column
-import ru.landgrafhomyak.serdha.api.v0.misc.Expression
+import ru.landgrafhomyak.serdha.api.v0.misc.IntermediateColumn
 import ru.landgrafhomyak.serdha.api.v0.misc.DatabaseType
+import ru.landgrafhomyak.serdha.api.v0.misc.Expression
 
-/**
- * Descriptor of 'check' constraint on columns. Used for schema manipulations.
- *
- * @param TableUserExtension Type of [owner table's][CheckConstraint.table] user expression for static reporting errors when this descriptor passed to wrong table.
- */
 public interface CheckConstraint<TableUserExtension : Any> {
-	/**
-	 * Name of constraint for debugging, errors and raw schema access.
-	 */
 	@Suppress("INAPPLICABLE_JVM_NAME")
 	@get:JvmName("name")
 	public val name: String
 
-	/**
-	 * Table that contains this constraint. For debugging.
-	 */
 	@Suppress("INAPPLICABLE_JVM_NAME")
 	@get:JvmName("table")
 	public val table: Table<TableUserExtension, *>
 
+	public interface Creator<ConstraintUserExtension : Any, TargetTableUserExtension : Any> {
+		public fun createCheckConstraint(scope: Scope<ConstraintUserExtension, TargetTableUserExtension>)
 
-	/**
-	 * Expression used to check data.
-	 */
-	@Suppress("INAPPLICABLE_JVM_NAME")
-	@get:JvmName("expression")
-	public val expression: Expression<Boolean, DatabaseType.BOOLEAN, TableUserExtension>
+		public interface Scope<ConstraintUserExtension : Any, TargetTableUserExtension : Any> {
+			public var result: IntermediateColumn<Boolean, DatabaseType.BOOLEAN, ConstraintUserExtension>
+			public fun <RT, DT : DatabaseType<RT>> selectFromTargetTable(column: Column<RT, DT, TargetTableUserExtension>): IntermediateColumn<RT, DT, ConstraintUserExtension>
 
+			public fun <ReferencedTableUserExtension : Any, RT, DT : DatabaseType<RT>> followReference(
+				ref: IntermediateColumn<*, DatabaseType.ROW_ID<ReferencedTableUserExtension>, ConstraintUserExtension>,
+				column: Column<RT, DT, ReferencedTableUserExtension>
+			): IntermediateColumn<RT, DT, ReferencedTableUserExtension>
 
-	/**
-	 * Set of columns, checked by this constraint. Calculated from [CheckConstraint.expression]. For debugging.
-	 */
-	@Suppress("INAPPLICABLE_JVM_NAME")
-	@get:JvmName("affectedColumns")
-	public val affectedColumns: List<Column<*, *, TableUserExtension>>
+			public val builtinExpressions: BuiltinExpressionsProvider<ConstraintUserExtension>
+			public fun <ExpressionUserExtension : Any> mapColumns(
+				expression: Expression<ExpressionUserExtension>,
+				input: Expression.InputLinker<ExpressionUserExtension, ConstraintUserExtension>,
+				output: Expression.OutputLinker<ExpressionUserExtension, ConstraintUserExtension>
+			)
+		}
+	}
 }
\ No newline at end of file
diff --git a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/CreateTableScope.kt b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/CreateTableScope.kt
index dd472a4..3c6aadc 100644
--- a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/CreateTableScope.kt
+++ b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/CreateTableScope.kt
@@ -6,8 +6,6 @@ import ru.landgrafhomyak.serdha.api.v0.misc.DatabaseType
 import ru.landgrafhomyak.serdha.api.v0.misc.DatabaseTypesProvider
 
 public interface CreateTableScope<TableUserExtension : Any> {
-	public val expressionBuilder: BuiltinExpressionsProvider<TableUserExtension>
-
 	public val types: DatabaseTypesProvider
 
 	public fun <RT, DT : DatabaseType<RT>> column(name: String, type: DT): Column<RT, DT, TableUserExtension>
@@ -15,8 +13,8 @@ public interface CreateTableScope<TableUserExtension : Any> {
 	public fun index(name: String, vararg columns: Column<*, *, TableUserExtension>): Index<TableUserExtension>
 
 	public fun uniqueIndex(name: String, distinctNulls: Boolean, vararg columns: Column<*, *, TableUserExtension>): UniqueIndex<TableUserExtension>
-	public fun checkConstraint(name: String, constraint: Expression<Boolean, DatabaseType.BOOLEAN, TableUserExtension>): CheckConstraint<TableUserExtension>
-	public fun <RT : Any, DT : DatabaseType<RT>> defaultValue(c: Column<RT, DT, TableUserExtension>, expr: Expression<RT, DT, TableUserExtension>): DefaultConstraint<RT, DT, TableUserExtension>
+	public fun <ConstraintUserExtension : Any> checkConstraint(name: String, creator: CheckConstraint.Creator<ConstraintUserExtension, TableUserExtension>, recheckExistingRows: Boolean = false): CheckConstraint<TableUserExtension>
+	public fun <ConstraintUserExtension : Any, RT : Any, DT : DatabaseType<RT>> defaultValue(c: Column<RT, DT, TableUserExtension>, creator: DefaultConstraint.Creator<ConstraintUserExtension, RT, DT, TableUserExtension>): DefaultConstraint<TableUserExtension>
 
 	@Suppress("PropertyName")
 	public val rowId_column: Column<RowId<TableUserExtension>, DatabaseType<RowId<TableUserExtension>>, TableUserExtension>
diff --git a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/DefaultConstraint.kt b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/DefaultConstraint.kt
index c8a3830..0f4750a 100644
--- a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/DefaultConstraint.kt
+++ b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/DefaultConstraint.kt
@@ -1,43 +1,39 @@
 package ru.landgrafhomyak.serdha.api.v0.table
 
 import kotlin.jvm.JvmName
+import ru.landgrafhomyak.serdha.api.v0.misc.BuiltinExpressionsProvider
 import ru.landgrafhomyak.serdha.api.v0.misc.Column
-import ru.landgrafhomyak.serdha.api.v0.misc.Expression
+import ru.landgrafhomyak.serdha.api.v0.misc.IntermediateColumn
 import ru.landgrafhomyak.serdha.api.v0.misc.DatabaseType
+import ru.landgrafhomyak.serdha.api.v0.misc.Expression
 
-/**
- * Descriptor of default value attached to [column][Column]. Used for schema manipulations.
- *
- * @param RT Type in programming language to which database type is converted.
- * @param DT Descriptor of column type on database side.
- * @param TableUserExtension Type of [owner's table][Column.table] user expression for static reporting errors when this descriptor passed to wrong table.
- */
-public interface DefaultConstraint<RT, DT : DatabaseType<RT>, TableUserExtension : Any> {
-	/**
-	 * Name of constraint for debugging, errors and raw schema access.
-	 */
+public interface DefaultConstraint<TableUserExtension : Any> {
 	@Suppress("INAPPLICABLE_JVM_NAME")
 	@get:JvmName("name")
 	public val name: String
 
-	/**
-	 * Table, that contains this constraint. For debugging.
-	 */
 	@Suppress("INAPPLICABLE_JVM_NAME")
 	@get:JvmName("table")
 	public val table: Table<TableUserExtension, *>
 
-	/**
-	 * Column which will get value from this constraint if not initialized manually. For debugging.
-	 */
-	@Suppress("INAPPLICABLE_JVM_NAME")
-	@get:JvmName("attachedToColumn")
-	public val attachedToColumn: Column<RT, DT, TableUserExtension>
+	public interface Creator<ConstraintUserExtension : Any, RT, DT : DatabaseType<RT>, TargetTableUserExtension : Any> {
+		public fun createCheckConstraint(scope: Scope<ConstraintUserExtension, RT, DT, TargetTableUserExtension>)
 
-	/**
-	 * Expression used to initialize cell.
-	 */
-	@Suppress("INAPPLICABLE_JVM_NAME")
-	@get:JvmName("expression")
-	public val expression: Expression<RT, DT, TableUserExtension>
+		public interface Scope<ConstraintUserExtension : Any, rRT, rDT : DatabaseType<rRT>, TargetTableUserExtension : Any> {
+			public var result: IntermediateColumn<rRT, rDT, ConstraintUserExtension>
+			public fun <RT, DT : DatabaseType<RT>> selectFromTargetTable(column: Column<RT, DT, TargetTableUserExtension>): IntermediateColumn<RT, DT, ConstraintUserExtension>
+
+			public fun <ReferencedTableUserExtension : Any, RT, DT : DatabaseType<RT>> followReference(
+				ref: IntermediateColumn<*, DatabaseType.ROW_ID<ReferencedTableUserExtension>, ConstraintUserExtension>,
+				column: Column<RT, DT, ReferencedTableUserExtension>
+			): IntermediateColumn<RT, DT, ReferencedTableUserExtension>
+
+			public val builtinExpressions: BuiltinExpressionsProvider<ConstraintUserExtension>
+			public fun <ExpressionUserExtension : Any> mapColumns(
+				expression: Expression<ExpressionUserExtension>,
+				input: Expression.InputLinker<ExpressionUserExtension, ConstraintUserExtension>,
+				output: Expression.OutputLinker<ExpressionUserExtension, ConstraintUserExtension>
+			)
+		}
+	}
 }
\ No newline at end of file
diff --git a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/UpdateTableScope.kt b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/UpdateTableScope.kt
index e686aa6..f77fa02 100644
--- a/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/UpdateTableScope.kt
+++ b/src/commonMain/kotlin/ru/landgrafhomyak/serdha/api/v0/table/UpdateTableScope.kt
@@ -7,8 +7,6 @@ import ru.landgrafhomyak.serdha.api.v0.misc.DatabaseType
 
 
 public interface UpdateTableScope<TableNewUserExtension : Any, TableOldUserExtension : Any> : CreateTableScope<TableNewUserExtension> {
-	public val oldExpressionBuilder: BuiltinExpressionsProvider<TableOldUserExtension>
-
 	public fun <RT, DT : DatabaseType<RT>> keepColumn(c: Column<RT, DT, TableOldUserExtension>): Column<RT, DT, TableNewUserExtension>
 	public fun <RT, DT : DatabaseType<RT>> keepColumnUntilUpgrading(c: Column<RT, DT, TableOldUserExtension>): Column<RT, DT, TableNewUserExtension>
 	public fun <RT, DT : DatabaseType<RT>> renameAndKeepColumn(c: Column<RT, DT, TableOldUserExtension>, newName: String): Column<RT, DT, TableNewUserExtension>
@@ -26,9 +24,9 @@ public interface UpdateTableScope<TableNewUserExtension : Any, TableOldUserExten
 	public fun renameAndKeepUniqueIndex(i: UniqueIndex<TableOldUserExtension>, newName: String): UniqueIndex<TableNewUserExtension>
 	public fun deleteUniqueIndex(i: UniqueIndex<TableOldUserExtension>)
 
-	public fun <RT, DT : DatabaseType<RT>> keepDefaultValue(c: Column<RT, DT, TableNewUserExtension>, d: DefaultConstraint<RT, DT, TableOldUserExtension>): DefaultConstraint<RT, DT, TableNewUserExtension>
-	public fun <RT, DT : DatabaseType<RT>> changeDefaultValue(c: Column<RT, DT, TableNewUserExtension>, d: DefaultConstraint<*, *, TableOldUserExtension>): DefaultConstraint<RT, DT, TableNewUserExtension>
-	public fun deleteDefaultValue(i: DefaultConstraint<*, *, TableOldUserExtension>)
+	public fun <RT, DT : DatabaseType<RT>> keepDefaultValue(c: Column<RT, DT, TableNewUserExtension>, d: DefaultConstraint<TableOldUserExtension>): DefaultConstraint<TableNewUserExtension>
+	public fun <RT, DT : DatabaseType<RT>> changeDefaultValue(c: Column<RT, DT, TableNewUserExtension>, d: DefaultConstraint<TableOldUserExtension>): DefaultConstraint<TableNewUserExtension>
+	public fun deleteDefaultValue(i: DefaultConstraint<TableOldUserExtension>)
 
 	public fun <TargetTableUserWrapper : Any> keepForeignRowReference(
 		frr: ForeignRowReference<TableOldUserExtension, TargetTableUserWrapper>,