Added clearGroupBy() (#921)

* added clearGroupBy

* fix clearGroupBy comment by adding a groupBy to be cleared

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

@@ -218,4 +218,11 @@ export const SelectQueryNode = freeze({
       orderBy: undefined,
     })
   },
+
+  cloneWithoutGroupBy(select: SelectQueryNode): SelectQueryNode {
+    return freeze({
+      ...select,
+      groupBy: undefined,
+    })
+  },
 })

src/query-builder/select-query-builder.ts

@@ -1500,6 +1500,26 @@ export interface SelectQueryBuilder<DB, TB extends keyof DB, O>
    */
   clearOrderBy(): SelectQueryBuilder<DB, TB, O>
 
+  /**
+   * Clears `group by` clause from the query.
+   *
+   * ### Examples
+   *
+   * ```ts
+   * db.selectFrom('person')
+   *   .selectAll()
+   *   .groupBy('id')
+   *   .clearGroupBy()
+   * ```
+   *
+   * The generated SQL(PostgreSQL):
+   *
+   * ```sql
+   * select * from "person"
+   * ```
+   */
+  clearGroupBy(): SelectQueryBuilder<DB, TB, O>
+
   /**
    * Simply calls the provided function passing `this` as the only argument. `$call` returns
    * what the provided function returns.
@@ -2279,6 +2299,13 @@ class SelectQueryBuilderImpl<DB, TB extends keyof DB, O>
     })
   }
 
+  clearGroupBy(): SelectQueryBuilder<DB, TB, O> {
+    return new SelectQueryBuilderImpl<DB, TB, O>({
+      ...this.#props,
+      queryNode: SelectQueryNode.cloneWithoutGroupBy(this.#props.queryNode),
+    })
+  }
+
   $call<T>(func: (qb: this) => T): T {
     return func(this)
   }

test/node/src/clear.test.ts

@@ -395,5 +395,32 @@ for (const dialect of DIALECTS) {
         },
       })
     })
+
+    it('should clear groupBy', () => {
+      const query = ctx.db
+        .selectFrom('person')
+        .selectAll()
+        .groupBy('id')
+        .clearGroupBy()
+
+      testSql(query, dialect, {
+        postgres: {
+          sql: `select * from "person"`,
+          parameters: [],
+        },
+        mysql: {
+          sql: 'select * from `person`',
+          parameters: [],
+        },
+        mssql: {
+          sql: `select * from "person"`,
+          parameters: [],
+        },
+        sqlite: {
+          sql: `select * from "person"`,
+          parameters: [],
+        },
+      })
+    })
   })
 }