diff --git a/expression/builtin_cast.go b/expression/builtin_cast.go
index 1d356371c41f1..4ded234059ae1 100644
--- a/expression/builtin_cast.go
+++ b/expression/builtin_cast.go
@@ -290,6 +290,9 @@ func (c *castAsStringFunctionClass) getFunction(ctx sessionctx.Context, args []E
 	argTp := args[0].GetType().EvalType()
 	switch argTp {
 	case types.ETInt:
+		if bf.tp.Flen == types.UnspecifiedLength {
+			bf.tp.Flen = args[0].GetType().Flen
+		}
 		sig = &builtinCastIntAsStringSig{bf}
 		sig.setPbCode(tipb.ScalarFuncSig_CastIntAsString)
 	case types.ETReal:
diff --git a/expression/integration_test.go b/expression/integration_test.go
index e2f620da24811..8aeca030d9c05 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -10198,3 +10198,73 @@ func (s *testIntegrationSuite) TestIssue28643(c *C) {
 	tk.MustExec("set tidb_enable_vectorized_expression = off;")
 	tk.MustQuery("select hour(a) from t;").Check(testkit.Rows("838", "838"))
 }
+<<<<<<< HEAD
+=======
+
+func (s *testIntegrationSuite) TestIssue27831(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(a enum(\"a\", \"b\"), b enum(\"a\", \"b\"), c bool)")
+	tk.MustExec("insert into t values(\"a\", \"a\", 1);")
+	tk.MustQuery("select * from t t1 right join t t2 on t1.a=t2.b and t1.a= t2.c;").Check(testkit.Rows("a a 1 a a 1"))
+
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(a enum(\"a\", \"b\"), b enum(\"a\", \"b\"), c bool, d int, index idx(d))")
+	tk.MustExec("insert into t values(\"a\", \"a\", 1, 1);")
+	tk.MustQuery("select /*+ inl_hash_join(t1) */  * from t t1 right join t t2 on t1.a=t2.b and t1.a= t2.c and t1.d=t2.d;").Check(testkit.Rows("a a 1 1 a a 1 1"))
+}
+
+func (s *testIntegrationSuite) TestIssue29434(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+
+	tk.MustExec("drop table if exists t1;")
+	tk.MustExec("create table t1(c1 datetime);")
+	tk.MustExec("insert into t1 values('2021-12-12 10:10:10.000');")
+	tk.MustExec("set tidb_enable_vectorized_expression = on;")
+	tk.MustQuery("select greatest(c1, '99999999999999') from t1;").Check(testkit.Rows("99999999999999"))
+	tk.MustExec("set tidb_enable_vectorized_expression = off;")
+	tk.MustQuery("select greatest(c1, '99999999999999') from t1;").Check(testkit.Rows("99999999999999"))
+
+	tk.MustExec("set tidb_enable_vectorized_expression = on;")
+	tk.MustQuery("select least(c1, '99999999999999') from t1;").Check(testkit.Rows("2021-12-12 10:10:10"))
+	tk.MustExec("set tidb_enable_vectorized_expression = off;")
+	tk.MustQuery("select least(c1, '99999999999999') from t1;").Check(testkit.Rows("2021-12-12 10:10:10"))
+}
+
+func (s *testIntegrationSuite) TestIssue29417(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t1;")
+	tk.MustExec("create table t1 (f1 decimal(5,5));")
+	tk.MustExec("insert into t1 values (-0.12345);")
+	tk.MustQuery("select concat(f1) from t1;").Check(testkit.Rows("-0.12345"))
+}
+
+func (s *testIntegrationSuite) TestIssue29244(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(a time(4));")
+	tk.MustExec("insert into t values(\"-700:10:10.123456111\");")
+	tk.MustExec("insert into t values(\"700:10:10.123456111\");")
+	tk.MustExec("set tidb_enable_vectorized_expression = on;")
+	tk.MustQuery("select microsecond(a) from t;").Check(testkit.Rows("123500", "123500"))
+	tk.MustExec("set tidb_enable_vectorized_expression = off;")
+	tk.MustQuery("select microsecond(a) from t;").Check(testkit.Rows("123500", "123500"))
+}
+
+func (s *testIntegrationSuite) TestIssue29513(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustQuery("select '123' union select cast(45678 as char);").Sort().Check(testkit.Rows("123", "45678"))
+	tk.MustQuery("select '123' union select cast(45678 as char(2));").Sort().Check(testkit.Rows("123", "45"))
+
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(a int);")
+	tk.MustExec("insert into t values(45678);")
+	tk.MustQuery("select '123' union select cast(a as char) from t;").Sort().Check(testkit.Rows("123", "45678"))
+	tk.MustQuery("select '123' union select cast(a as char(2)) from t;").Sort().Check(testkit.Rows("123", "45"))
+}
+>>>>>>> 8858592f7... expression: fix wrong flen for CastAsString funtion (#29563)
diff --git a/expression/typeinfer_test.go b/expression/typeinfer_test.go
index d289cdd880d01..2f4a93670026b 100644
--- a/expression/typeinfer_test.go
+++ b/expression/typeinfer_test.go
@@ -180,9 +180,9 @@ func (s *testInferTypeSuite) createTestCase4Constants() []typeInferTestCase {
 
 func (s *testInferTypeSuite) createTestCase4Cast() []typeInferTestCase {
 	return []typeInferTestCase{
-		{"CAST(c_int_d AS BINARY)", mysql.TypeVarString, charset.CharsetBin, mysql.BinaryFlag, -1, -1}, // TODO: Flen should be 11.
+		{"CAST(c_int_d AS BINARY)", mysql.TypeVarString, charset.CharsetBin, mysql.BinaryFlag, 11, -1},
 		{"CAST(c_int_d AS BINARY(5))", mysql.TypeString, charset.CharsetBin, mysql.BinaryFlag, 5, -1},
-		{"CAST(c_int_d AS CHAR)", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, -1, -1}, // TODO: Flen should be 11.
+		{"CAST(c_int_d AS CHAR)", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 11, -1},
 		{"CAST(c_int_d AS CHAR(5))", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 5, -1},
 		{"CAST(c_int_d AS DATE)", mysql.TypeDate, charset.CharsetBin, mysql.BinaryFlag, 10, 0},
 		{"CAST(c_int_d AS DATETIME)", mysql.TypeDatetime, charset.CharsetBin, mysql.BinaryFlag, 19, 0},
@@ -405,9 +405,15 @@ func (s *testInferTypeSuite) createTestCase4StrFuncs() []typeInferTestCase {
 
 		{"reverse(c_int_d      )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 20, types.UnspecifiedLength},
 		{"reverse(c_bigint_d   )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 20, types.UnspecifiedLength},
+<<<<<<< HEAD
 		{"reverse(c_float_d    )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, -1, types.UnspecifiedLength},
 		{"reverse(c_double_d   )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, -1, types.UnspecifiedLength},
 		{"reverse(c_decimal    )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 8, types.UnspecifiedLength},
+=======
+		{"reverse(c_float_d    )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, types.UnspecifiedLength, types.UnspecifiedLength},
+		{"reverse(c_double_d   )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, types.UnspecifiedLength, types.UnspecifiedLength},
+		{"reverse(c_decimal    )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 9, types.UnspecifiedLength},
+>>>>>>> 8858592f7... expression: fix wrong flen for CastAsString funtion (#29563)
 		{"reverse(c_char       )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 20, types.UnspecifiedLength},
 		{"reverse(c_varchar    )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 20, types.UnspecifiedLength},
 		{"reverse(c_text_d     )", mysql.TypeVarString, charset.CharsetUTF8MB4, 0, 65535, types.UnspecifiedLength},