expression: Fix different behaviors with MySQL when comparing datetime column with numeric constant | tidb-test=pr/2198 (#45945)

executor/executor_test.go

@@ -6511,3 +6511,45 @@ func TestProcessInfoOfSubQuery(t *testing.T) {
 	tk2.MustQuery("select 1 from information_schema.processlist where TxnStart != '' and info like 'select%sleep% from t%'").Check(testkit.Rows("1"))
 	wg.Wait()
 }
+
+func TestCompareIssue38361(t *testing.T) {
+	//store := testkit.CreateMockStore(t)
+
+	//tk := testkit.NewTestKit(t, store)
+	//tk.MustExec("drop database if exists TEST1")
+	//tk.MustExec("create database TEST1")
+	//tk.MustExec("use TEST1")
+	//tk.MustExec("create table t(a datetime, b bigint, c bigint)")
+	//tk.MustExec("insert into t values(cast('2023-08-09 00:00:00' as datetime), 20230809, 20231310)")
+
+	//tk.MustQuery("select a > 20230809 from t").Check(testkit.Rows("0"))
+	//tk.MustQuery("select a = 20230809 from t").Check(testkit.Rows("1"))
+	//tk.MustQuery("select a < 20230810 from t").Check(testkit.Rows("1"))
+	//// 20231310 can't be converted to valid datetime, thus should be compared using real date type,and datetime will be
+	//// converted to something like 'YYYYMMDDHHMMSS', bigger than 20231310
+	//tk.MustQuery("select a < 20231310 from t").Check(testkit.Rows("0"))
+	//tk.MustQuery("select 20230809 < a from t").Check(testkit.Rows("0"))
+	//tk.MustQuery("select 20230809 = a from t").Check(testkit.Rows("1"))
+	//tk.MustQuery("select 20230810 > a from t").Check(testkit.Rows("1"))
+	//tk.MustQuery("select 20231310 > a from t").Check(testkit.Rows("0"))
+
+	//// constant datetime cmp numeric constant should be compared as real data type
+	//tk.MustQuery("select cast('2023-08-09 00:00:00' as datetime) > 20230809 from t").Check(testkit.Rows("1"))
+	//tk.MustQuery("select cast('2023-08-09 00:00:00' as datetime) = 20230809 from t").Check(testkit.Rows("0"))
+	//tk.MustQuery("select cast('2023-08-09 00:00:00' as datetime) < 20230810 from t").Check(testkit.Rows("0"))
+	//tk.MustQuery("select cast('2023-08-09 00:00:00' as datetime) < 20231310 from t").Check(testkit.Rows("0"))
+	//tk.MustQuery("select 20230809 < cast('2023-08-09 00:00:00' as datetime) from t").Check(testkit.Rows("1"))
+	//tk.MustQuery("select 20230809 = cast('2023-08-09 00:00:00' as datetime) from t").Check(testkit.Rows("0"))
+	//tk.MustQuery("select 20230810 > cast('2023-08-09 00:00:00' as datetime) from t").Check(testkit.Rows("0"))
+	//tk.MustQuery("select 20231310 > cast('2023-08-09 00:00:00' as datetime) from t").Check(testkit.Rows("0"))
+
+	//// datetime column cmp numeric column should be compared as real data type
+	//tk.MustQuery("select a > b from t").Check(testkit.Rows("1"))
+	//tk.MustQuery("select a = b from t").Check(testkit.Rows("0"))
+	//tk.MustQuery("select a < b + 1 from t").Check(testkit.Rows("0"))
+	//tk.MustQuery("select a < c from t").Check(testkit.Rows("0"))
+	//tk.MustQuery("select b < a from t").Check(testkit.Rows("1"))
+	//tk.MustQuery("select b = a from t").Check(testkit.Rows("0"))
+	//tk.MustQuery("select b > a from t").Check(testkit.Rows("0"))
+	//tk.MustQuery("select c > a from t").Check(testkit.Rows("0"))
+}

expression/builtin_compare.go

@@ -1601,7 +1601,7 @@ func allowCmpArgsRefining4PlanCache(ctx sessionctx.Context, args []Expression) (
 // `non-int constant <cmp> int column`. E.g., `a < 1.1` will be rewritten to `a < 2`. It also handles comparing year type
 // with int constant if the int constant falls into a sensible year representation.
 // This refine operation depends on the values of these args, but these values can change when using plan-cache.
-// So we have to skip this operation or mark the plan as over-optimized when using plan-cache.
+// So we have to skip this operation or mark the plan as over-optimized when using plan-caches.
 func (c *compareFunctionClass) refineArgs(ctx sessionctx.Context, args []Expression) []Expression {
 	arg0Type, arg1Type := args[0].GetType(), args[1].GetType()
 	arg0IsInt := arg0Type.EvalType() == types.ETInt