#45 Add support for group by

src/dml/group-by.ts

@@ -0,0 +1,6 @@
+import { DatabaseRecord } from '../record';
+
+type AllowedKeys<T extends DatabaseRecord = DatabaseRecord> = keyof T & string;
+
+export type GroupBy<T extends DatabaseRecord = DatabaseRecord> =
+	AllowedKeys<T>[];

src/dml/index.ts

@@ -4,6 +4,7 @@ export { QueryRepository, QueryRepositoryOptions } from './query-repository';
 export * from './delete';
 export * from './insert';
 export * from './join';
+export * from './group-by';
 export * from './order-by';
 export * from './select';
 export * from './update';

src/dml/query-builder.ts

@@ -14,6 +14,7 @@ import { isCondition } from '../conditions';
 import { columnName } from '../tokens';
 import { DatabaseFunctionToken, isDatabaseFunction } from '../functions';
 import { DatabaseRecord } from '../record';
+import { GroupBy } from './group-by';
 
 export class DatabaseQueryBuilder extends StatementBuilder {
 	// ------------------------------------------------------------------------
@@ -320,6 +321,20 @@ export class DatabaseQueryBuilder extends StatementBuilder {
 		return this;
 	}
 
+	public groupBy(by: GroupBy): this {
+		this.sql.append('GROUP BY ');
+
+		for (const key of by) {
+			this.sql.columnName(key);
+			this.sql.append(', ');
+		}
+
+		this.sql.trimEnd(', ');
+		this.sql.space();
+
+		return this;
+	}
+
 	public orderBy(by: OrderBy) {
 		this.sql.append('ORDER BY ');
 
@@ -361,6 +376,10 @@ export class DatabaseQueryBuilder extends StatementBuilder {
 			this.where(query.where);
 		}
 
+		if (query.groupBy?.length) {
+			this.groupBy(query.groupBy);
+		}
+
 		if (query.orderBy) {
 			this.orderBy(query.orderBy);
 		}

src/dml/select.ts

@@ -1,6 +1,7 @@
 import { DatabaseFunctionToken } from '../functions/function-token';
 import { DatabaseRecord } from '../record';
 import { Join } from './join';
+import { GroupBy } from './group-by';
 import { OrderBy } from './order-by';
 import { Where } from './where';
 
@@ -32,5 +33,6 @@ export interface SelectQuery<T extends DatabaseRecord = DatabaseRecord> {
 	join?: Join[];
 	where?: Where<T> | Where<T>[];
 	limit?: number;
+	groupBy?: GroupBy<T>;
 	orderBy?: OrderBy<T>;
 }

test/spec/dml/query-builder.spec.ts

@@ -458,6 +458,22 @@ describe('Query Builder', () => {
 			expect(params).toEqual(['bob']);
 		});
 
+		it('can group by', () => {
+			const { sql, params } = new DatabaseQueryBuilder()
+				.select({
+					columns: ['id'],
+					table: 'user',
+					where: { fname: 'bob' },
+					groupBy: ['fname', 'id'],
+				})
+				.toDatabaseQuery();
+
+			expect(sql).toEqual(
+				'SELECT "id" FROM "user" WHERE ("fname" = ?) GROUP BY "fname", "id"'
+			);
+			expect(params).toEqual(['bob']);
+		});
+
 		it('can order by', () => {
 			const { sql, params } = new DatabaseQueryBuilder()
 				.select({