add OUTPUT clause support.

src/dialect/dialect-adapter-base.ts

@@ -20,6 +20,10 @@ export abstract class DialectAdapterBase implements DialectAdapter {
     return false
   }
 
+  get supportsOutput(): boolean {
+    return false
+  }
+
   abstract acquireMigrationLock(
     db: Kysely<any>,
     options: MigrationLockOptions,

src/dialect/dialect-adapter.ts

@@ -31,6 +31,12 @@ export interface DialectAdapter {
    */
   readonly supportsReturning: boolean
 
+  /**
+   * Whether or not this dialect supports the `output` clause in inserts
+   * updates and deletes.
+   */
+  readonly supportsOutput?: boolean
+
   /**
    * This method is used to acquire a lock for the migrations so that
    * it's not possible for two migration operations to run in parallel.

src/dialect/mssql/mssql-adapter.ts

@@ -12,10 +12,8 @@ export class MssqlAdapter extends DialectAdapterBase {
     return true
   }
 
-  get supportsReturning(): boolean {
-    // mssql should support returning with the `output` clause.
-    // we need to figure this out when we'll introduce support for it.
-    return false
+  get supportsOutput(): boolean {
+    return true
   }
 
   async acquireMigrationLock(db: Kysely<any>): Promise<void> {

src/index.ts

@@ -10,6 +10,7 @@ export * from './expression/expression-wrapper.js'
 
 export * from './query-builder/where-interface.js'
 export * from './query-builder/returning-interface.js'
+export * from './query-builder/output-interface.js'
 export * from './query-builder/having-interface.js'
 export * from './query-builder/select-query-builder.js'
 export * from './query-builder/insert-query-builder.js'
@@ -203,6 +204,7 @@ export * from './operation-node/merge-query-node.js'
 export * from './operation-node/matched-node.js'
 export * from './operation-node/fetch-node.js'
 export * from './operation-node/top-node.js'
+export * from './operation-node/output-node.js'
 
 export * from './util/column-type.js'
 export * from './util/compilable.js'

src/operation-node/delete-query-node.ts

@@ -11,6 +11,7 @@ import { OrderByItemNode } from './order-by-item-node.js'
 import { ExplainNode } from './explain-node.js'
 import { UsingNode } from './using-node.js'
 import { TopNode } from './top-node.js'
+import { OutputNode } from './output-node.js'
 
 export interface DeleteQueryNode extends OperationNode {
   readonly kind: 'DeleteQueryNode'
@@ -24,6 +25,7 @@ export interface DeleteQueryNode extends OperationNode {
   readonly limit?: LimitNode
   readonly explain?: ExplainNode
   readonly top?: TopNode
+  readonly output?: OutputNode
 }
 
 /**

src/operation-node/insert-query-node.ts

@@ -4,6 +4,7 @@ import { ExplainNode } from './explain-node.js'
 import { OnConflictNode } from './on-conflict-node.js'
 import { OnDuplicateKeyNode } from './on-duplicate-key-node.js'
 import { OperationNode } from './operation-node.js'
+import { OutputNode } from './output-node.js'
 import { ReturningNode } from './returning-node.js'
 import { TableNode } from './table-node.js'
 import { TopNode } from './top-node.js'
@@ -25,6 +26,7 @@ export interface InsertQueryNode extends OperationNode {
   readonly explain?: ExplainNode
   readonly defaultValues?: boolean
   readonly top?: TopNode
+  readonly output?: OutputNode
 }
 
 /**

src/operation-node/merge-query-node.ts

@@ -2,6 +2,7 @@ import { freeze } from '../util/object-utils.js'
 import { AliasNode } from './alias-node.js'
 import { JoinNode } from './join-node.js'
 import { OperationNode } from './operation-node.js'
+import { OutputNode } from './output-node.js'
 import { TableNode } from './table-node.js'
 import { TopNode } from './top-node.js'
 import { WhenNode } from './when-node.js'
@@ -14,6 +15,7 @@ export interface MergeQueryNode extends OperationNode {
   readonly whens?: ReadonlyArray<WhenNode>
   readonly with?: WithNode
   readonly top?: TopNode
+  readonly output?: OutputNode
 }
 
 /**

src/operation-node/operation-node-transformer.ts

@@ -93,6 +93,7 @@ import { AddIndexNode } from './add-index-node.js'
 import { CastNode } from './cast-node.js'
 import { FetchNode } from './fetch-node.js'
 import { TopNode } from './top-node.js'
+import { OutputNode } from './output-node.js'
 
 /**
  * Transforms an operation node tree into another one.
@@ -220,6 +221,7 @@ export class OperationNodeTransformer {
     CastNode: this.transformCast.bind(this),
     FetchNode: this.transformFetch.bind(this),
     TopNode: this.transformTop.bind(this),
+    OutputNode: this.transformOutput.bind(this),
   })
 
   transformNode<T extends OperationNode | undefined>(node: T): T {
@@ -384,6 +386,7 @@ export class OperationNodeTransformer {
       explain: this.transformNode(node.explain),
       defaultValues: node.defaultValues,
       top: this.transformNode(node.top),
+      output: this.transformNode(node.output),
     })
   }
 
@@ -407,6 +410,7 @@ export class OperationNodeTransformer {
       limit: this.transformNode(node.limit),
       explain: this.transformNode(node.explain),
       top: this.transformNode(node.top),
+      output: this.transformNode(node.output),
     })
   }
 
@@ -514,6 +518,7 @@ export class OperationNodeTransformer {
       explain: this.transformNode(node.explain),
       limit: this.transformNode(node.limit),
       top: this.transformNode(node.top),
+      output: this.transformNode(node.output),
     })
   }
 
@@ -1008,6 +1013,7 @@ export class OperationNodeTransformer {
       whens: this.transformNodeList(node.whens),
       with: this.transformNode(node.with),
       top: this.transformNode(node.top),
+      output: this.transformNode(node.output),
     })
   }
 
@@ -1054,6 +1060,13 @@ export class OperationNodeTransformer {
     })
   }
 
+  protected transformOutput(node: OutputNode): OutputNode {
+    return requireAllProps<OutputNode>({
+      kind: 'OutputNode',
+      selections: this.transformNodeList(node.selections),
+    })
+  }
+
   protected transformDataType(node: DataTypeNode): DataTypeNode {
     // An Object.freezed leaf node. No need to clone.
     return node

src/operation-node/operation-node-visitor.ts

@@ -95,6 +95,7 @@ import { AddIndexNode } from './add-index-node.js'
 import { CastNode } from './cast-node.js'
 import { FetchNode } from './fetch-node.js'
 import { TopNode } from './top-node.js'
+import { OutputNode } from './output-node.js'
 
 export abstract class OperationNodeVisitor {
   protected readonly nodeStack: OperationNode[] = []
@@ -197,6 +198,7 @@ export abstract class OperationNodeVisitor {
     CastNode: this.visitCast.bind(this),
     FetchNode: this.visitFetch.bind(this),
     TopNode: this.visitTop.bind(this),
+    OutputNode: this.visitOutput.bind(this),
   })
 
   protected readonly visitNode = (node: OperationNode): void => {
@@ -307,4 +309,5 @@ export abstract class OperationNodeVisitor {
   protected abstract visitCast(node: CastNode): void
   protected abstract visitFetch(node: FetchNode): void
   protected abstract visitTop(node: TopNode): void
+  protected abstract visitOutput(node: OutputNode): void
 }

src/operation-node/operation-node.ts

@@ -91,6 +91,7 @@ export type OperationNodeKind =
   | 'CastNode'
   | 'FetchNode'
   | 'TopNode'
+  | 'OutputNode'
 
 export interface OperationNode {
   readonly kind: OperationNodeKind

src/operation-node/output-node.ts

@@ -0,0 +1,35 @@
+import { freeze } from '../util/object-utils.js'
+import { OperationNode } from './operation-node.js'
+
+export interface OutputNode extends OperationNode {
+  readonly kind: 'OutputNode'
+  readonly selections: ReadonlyArray<OperationNode>
+}
+
+/**
+ * @internal
+ */
+export const OutputNode = freeze({
+  is(node: OperationNode): node is OutputNode {
+    return node.kind === 'OutputNode'
+  },
+
+  create(selections: ReadonlyArray<OperationNode>): OutputNode {
+    return freeze({
+      kind: 'OutputNode',
+      selections: freeze(selections),
+    })
+  },
+
+  cloneWithSelections(
+    output: OutputNode,
+    selections: ReadonlyArray<OperationNode>
+  ): OutputNode {
+    return freeze({
+      ...output,
+      selections: output.selections
+        ? freeze([...output.selections, ...selections])
+        : freeze(selections),
+    })
+  },
+})

src/operation-node/query-node.ts

@@ -13,6 +13,7 @@ import { ExplainFormat } from '../util/explainable.js'
 import { Expression } from '../expression/expression.js'
 import { MergeQueryNode } from './merge-query-node.js'
 import { TopNode } from './top-node.js'
+import { OutputNode } from './output-node.js'
 
 export type QueryNode =
   | SelectQueryNode
@@ -26,6 +27,7 @@ type HasWhere = { where?: WhereNode }
 type HasReturning = { returning?: ReturningNode }
 type HasExplain = { explain?: ExplainNode }
 type HasTop = { top?: TopNode }
+type HasOutput = { output?: OutputNode }
 
 /**
  * @internal
@@ -100,4 +102,16 @@ export const QueryNode = freeze({
       top,
     })
   },
+
+  cloneWithOutput<T extends HasOutput>(
+    node: T,
+    selections: ReadonlyArray<SelectionNode>,
+  ): T {
+    return freeze({
+      ...node,
+      output: node.output
+        ? OutputNode.cloneWithSelections(node.output, selections)
+        : OutputNode.create(selections),
+    })
+  },
 })

src/operation-node/update-query-node.ts

@@ -11,6 +11,7 @@ import { FromNode } from './from-node.js'
 import { ExplainNode } from './explain-node.js'
 import { LimitNode } from './limit-node.js'
 import { TopNode } from './top-node.js'
+import { OutputNode } from './output-node.js'
 
 export type UpdateValuesNode = ValueListNode | PrimitiveValueListNode
 
@@ -26,6 +27,7 @@ export interface UpdateQueryNode extends OperationNode {
   readonly explain?: ExplainNode
   readonly limit?: LimitNode
   readonly top?: TopNode
+  readonly output?: OutputNode
 }
 
 /**

src/parser/returning-parser.ts

@@ -1,38 +1,29 @@
 import { DeleteResult } from '../query-builder/delete-result.js'
 import { InsertResult } from '../query-builder/insert-result.js'
+import { MergeResult } from '../query-builder/merge-result.js'
 import { UpdateResult } from '../query-builder/update-result.js'
 import { Selection, AllSelection, CallbackSelection } from './select-parser.js'
 
-export type ReturningRow<
-  DB,
-  TB extends keyof DB,
-  O,
-  SE,
-> = O extends InsertResult
+export type ReturningRow<DB, TB extends keyof DB, O, SE> = O extends
+  | InsertResult
+  | DeleteResult
+  | UpdateResult
+  | MergeResult
   ? Selection<DB, TB, SE>
-  : O extends DeleteResult
-    ? Selection<DB, TB, SE>
-    : O extends UpdateResult
-      ? Selection<DB, TB, SE>
-      : O & Selection<DB, TB, SE>
+  : O & Selection<DB, TB, SE>
 
-export type ReturningCallbackRow<
-  DB,
-  TB extends keyof DB,
-  O,
-  CB,
-> = O extends InsertResult
+export type ReturningCallbackRow<DB, TB extends keyof DB, O, CB> = O extends
+  | InsertResult
+  | DeleteResult
+  | UpdateResult
+  | MergeResult
   ? CallbackSelection<DB, TB, CB>
-  : O extends DeleteResult
-    ? CallbackSelection<DB, TB, CB>
-    : O extends UpdateResult
-      ? CallbackSelection<DB, TB, CB>
-      : O & CallbackSelection<DB, TB, CB>
+  : O & CallbackSelection<DB, TB, CB>
 
-export type ReturningAllRow<DB, TB extends keyof DB, O> = O extends InsertResult
+export type ReturningAllRow<DB, TB extends keyof DB, O> = O extends
+  | InsertResult
+  | DeleteResult
+  | UpdateResult
+  | MergeResult
   ? AllSelection<DB, TB>
-  : O extends DeleteResult
-    ? AllSelection<DB, TB>
-    : O extends UpdateResult
-      ? AllSelection<DB, TB>
-      : O & AllSelection<DB, TB>
+  : O & AllSelection<DB, TB>