diff --git a/ddl/column_type_change_test.go b/ddl/column_type_change_test.go
index 33e9aa1426efe..cc8b9284defcb 100644
--- a/ddl/column_type_change_test.go
+++ b/ddl/column_type_change_test.go
@@ -1200,7 +1200,8 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 				i json,
 				ui json,
 				f64 json,
-				str json
+				str json,
+				nul json
 			)
 		`)
 	}
@@ -1208,7 +1209,7 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	// To numeric data types.
 	// tinyint
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	// MySQL will get "ERROR 1366 (HY000) Incorrect integer value: '{"obj": 100}' for column 'obj' at row 1".
 	tk.MustGetErrCode("alter table t modify obj tinyint", mysql.ErrTruncatedWrongValue)
 	// MySQL will get "ERROR 1366 (HY000) Incorrect integer value: '[-1, 0, 1]' for column 'arr' at row 1".
@@ -1224,11 +1225,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustGetErrCode("alter table t modify f64 tinyint", mysql.ErrDataOutOfRange)
 	// MySQL will get "ERROR 1366 (HY000) Incorrect integer value: '"json string"' for column 'str' at row 1".
 	tk.MustGetErrCode("alter table t modify str tinyint", mysql.ErrTruncatedWrongValue)
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null 1 0 -22 22 323232323.32323235 \"json string\""))
+	tk.MustExec("alter table t modify nul tinyint")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null 1 0 -22 22 323232323.32323235 \"json string\" <nil>"))
 
 	// int
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	// MySQL will get "ERROR 1366 (HY000) Incorrect integer value: '{"obj": 100}' for column 'obj' at row 1".
 	tk.MustGetErrCode("alter table t modify obj int", mysql.ErrTruncatedWrongValue)
 	// MySQL will get "ERROR 1366 (HY000) Incorrect integer value: '[-1, 0, 1]' for column 'arr' at row 1".
@@ -1244,11 +1246,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify f64 int")
 	// MySQL will get "ERROR 1366 (HY000) Incorrect integer value: '"json string"' for column 'str' at row 1".
 	tk.MustGetErrCode("alter table t modify str int", mysql.ErrTruncatedWrongValue)
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null 1 0 -22 22 323232323 \"json string\""))
+	tk.MustExec("alter table t modify nul int")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null 1 0 -22 22 323232323 \"json string\" <nil>"))
 
 	// bigint
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	// MySQL will get "ERROR 1366 (HY000) Incorrect integer value: '{"obj": 100}' for column 'obj' at row 1".
 	tk.MustGetErrCode("alter table t modify obj bigint", mysql.ErrTruncatedWrongValue)
 	// MySQL will get "ERROR 1366 (HY000) Incorrect integer value: '[-1, 0, 1]' for column 'arr' at row 1".
@@ -1264,11 +1267,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify f64 bigint")
 	// MySQL will get "ERROR 1366 (HY000) Incorrect integer value: '"json string"' for column 'str' at row 1".
 	tk.MustGetErrCode("alter table t modify str bigint", mysql.ErrTruncatedWrongValue)
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null 1 0 -22 22 323232323 \"json string\""))
+	tk.MustExec("alter table t modify nul bigint")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null 1 0 -22 22 323232323 \"json string\" <nil>"))
 
 	// unsigned bigint
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	// MySQL will get "ERROR 1366 (HY000) Incorrect integer value: '{"obj": 100}' for column 'obj' at row 1".
 	tk.MustGetErrCode("alter table t modify obj bigint unsigned", mysql.ErrTruncatedWrongValue)
 	// MySQL will get "ERROR 1366 (HY000) Incorrect integer value: '[-1, 0, 1]' for column 'arr' at row 1".
@@ -1285,11 +1289,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify f64 bigint unsigned")
 	// MySQL will get "ERROR 1366 (HY000) Incorrect integer value: '"json string"' for column 'str' at row 1".
 	tk.MustGetErrCode("alter table t modify str bigint unsigned", mysql.ErrTruncatedWrongValue)
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null 1 0 -22 22 323232323 \"json string\""))
+	tk.MustExec("alter table t modify nul bigint unsigned")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null 1 0 -22 22 323232323 \"json string\" <nil>"))
 
 	// bit
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	tk.MustGetErrCode("alter table t modify obj bit", mysql.ErrUnsupportedDDLOperation)
 	tk.MustGetErrCode("alter table t modify arr bit", mysql.ErrUnsupportedDDLOperation)
 	tk.MustGetErrCode("alter table t modify nil bit", mysql.ErrUnsupportedDDLOperation)
@@ -1299,11 +1304,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustGetErrCode("alter table t modify ui bit", mysql.ErrUnsupportedDDLOperation)
 	tk.MustGetErrCode("alter table t modify f64 bit", mysql.ErrUnsupportedDDLOperation)
 	tk.MustGetErrCode("alter table t modify str bit", mysql.ErrUnsupportedDDLOperation)
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false -22 22 323232323.32323235 \"json string\""))
+	tk.MustGetErrCode("alter table t modify nul bit", mysql.ErrUnsupportedDDLOperation)
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false -22 22 323232323.32323235 \"json string\" <nil>"))
 
 	// decimal
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	// MySQL will get "ERROR 3156 (22001) Invalid JSON value for CAST to DECIMAL from column obj at row 1".
 	tk.MustGetErrCode("alter table t modify obj decimal(20, 10)", mysql.ErrTruncatedWrongValue)
 	// MySQL will get "ERROR 3156 (22001) Invalid JSON value for CAST to DECIMAL from column arr at row 1".
@@ -1317,11 +1323,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify f64 decimal(20, 10)")
 	// MySQL will get "ERROR 1366 (HY000): Incorrect DECIMAL value: '0' for column '' at row -1".
 	tk.MustGetErrCode("alter table t modify str decimal(20, 10)", mysql.ErrBadNumber)
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null 1.0000000000 0.0000000000 -22.0000000000 22.0000000000 323232323.3232323500 \"json string\""))
+	tk.MustExec("alter table t modify nul decimal(20, 10)")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null 1.0000000000 0.0000000000 -22.0000000000 22.0000000000 323232323.3232323500 \"json string\" <nil>"))
 
 	// double
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	// MySQL will get "ERROR 1265 (01000): Data truncated for column 'obj' at row 1".
 	tk.MustGetErrCode("alter table t modify obj double", mysql.ErrTruncatedWrongValue)
 	// MySQL will get "ERROR 1265 (01000): Data truncated for column 'arr' at row 1".
@@ -1337,12 +1344,13 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify f64 double")
 	// MySQL will get "ERROR 1265 (01000): Data truncated for column 'str' at row 1".
 	tk.MustGetErrCode("alter table t modify str double", mysql.ErrTruncatedWrongValue)
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null 1 0 -22 22 323232323.32323235 \"json string\""))
+	tk.MustExec("alter table t modify nul double")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null 1 0 -22 22 323232323.32323235 \"json string\" <nil>"))
 
 	// To string data types.
 	// char
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	tk.MustExec("alter table t modify obj char(20)")
 	tk.MustExec("alter table t modify arr char(20)")
 	tk.MustExec("alter table t modify nil char(20)")
@@ -1352,11 +1360,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify ui char(20)")
 	tk.MustExec("alter table t modify f64 char(20)")
 	tk.MustExec("alter table t modify str char(20)")
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false -22 22 323232323.32323235 \"json string\""))
+	tk.MustExec("alter table t modify nil char(20)")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false -22 22 323232323.32323235 \"json string\" <nil>"))
 
 	// varchar
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	tk.MustExec("alter table t modify obj varchar(20)")
 	tk.MustExec("alter table t modify arr varchar(20)")
 	tk.MustExec("alter table t modify nil varchar(20)")
@@ -1366,11 +1375,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify ui varchar(20)")
 	tk.MustExec("alter table t modify f64 varchar(20)")
 	tk.MustExec("alter table t modify str varchar(20)")
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false -22 22 323232323.32323235 \"json string\""))
+	tk.MustExec("alter table t modify nul varchar(20)")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false -22 22 323232323.32323235 \"json string\" <nil>"))
 
 	// binary
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	tk.MustExec("alter table t modify obj binary(20)")
 	tk.MustExec("alter table t modify arr binary(20)")
 	tk.MustExec("alter table t modify nil binary(20)")
@@ -1380,6 +1390,7 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify ui binary(20)")
 	tk.MustExec("alter table t modify f64 binary(20)")
 	tk.MustExec("alter table t modify str binary(20)")
+	tk.MustExec("alter table t modify nul binary(20)")
 	tk.MustQuery("select * from t").Check(testkit.Rows(
 		"{\"obj\": 100}\x00\x00\x00\x00\x00\x00\x00\x00 " +
 			"[-1, 0, 1]\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00 " +
@@ -1389,10 +1400,10 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 			"-22\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00 " +
 			"22\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00 " +
 			"323232323.32323235\x00\x00 " +
-			"\"json string\"\x00\x00\x00\x00\x00\x00\x00"))
+			"\"json string\"\x00\x00\x00\x00\x00\x00\x00 <nil>"))
 	// varbinary
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	tk.MustExec("alter table t modify obj varbinary(20)")
 	tk.MustExec("alter table t modify arr varbinary(20)")
 	tk.MustExec("alter table t modify nil varbinary(20)")
@@ -1402,11 +1413,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify ui varbinary(20)")
 	tk.MustExec("alter table t modify f64 varbinary(20)")
 	tk.MustExec("alter table t modify str varbinary(20)")
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false -22 22 323232323.32323235 \"json string\""))
+	tk.MustExec("alter table t modify nul varbinary(20)")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false -22 22 323232323.32323235 \"json string\" <nil>"))
 
 	// blob
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	tk.MustExec("alter table t modify obj blob")
 	tk.MustExec("alter table t modify arr blob")
 	tk.MustExec("alter table t modify nil blob")
@@ -1416,11 +1428,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify ui blob")
 	tk.MustExec("alter table t modify f64 blob")
 	tk.MustExec("alter table t modify str blob")
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false -22 22 323232323.32323235 \"json string\""))
+	tk.MustExec("alter table t modify nul blob")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false -22 22 323232323.32323235 \"json string\" <nil>"))
 
 	// text
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	tk.MustExec("alter table t modify obj text")
 	tk.MustExec("alter table t modify arr text")
 	tk.MustExec("alter table t modify nil text")
@@ -1430,11 +1443,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify ui text")
 	tk.MustExec("alter table t modify f64 text")
 	tk.MustExec("alter table t modify str text")
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false -22 22 323232323.32323235 \"json string\""))
+	tk.MustExec("alter table t modify nul text")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false -22 22 323232323.32323235 \"json string\" <nil>"))
 
 	// enum
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	tk.MustGetErrCode("alter table t modify obj enum('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')", mysql.ErrUnsupportedDDLOperation)
 	tk.MustGetErrCode("alter table t modify arr enum('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')", mysql.ErrUnsupportedDDLOperation)
 	tk.MustGetErrCode("alter table t modify nil enum('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')", mysql.ErrUnsupportedDDLOperation)
@@ -1444,11 +1458,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustGetErrCode("alter table t modify ui enum('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')", mysql.ErrUnsupportedDDLOperation)
 	tk.MustGetErrCode("alter table t modify f64 enum('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')", mysql.ErrUnsupportedDDLOperation)
 	tk.MustGetErrCode("alter table t modify str enum('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')", mysql.ErrUnsupportedDDLOperation)
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false -22 22 323232323.32323235 \"json string\""))
+	tk.MustGetErrCode("alter table t modify nul enum('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')", mysql.ErrUnsupportedDDLOperation)
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false -22 22 323232323.32323235 \"json string\" <nil>"))
 
 	// set
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"', null)")
 	tk.MustGetErrCode("alter table t modify obj set('{\"obj\": 100}', '[-1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')", mysql.ErrUnsupportedDDLOperation)
 	tk.MustGetErrCode("alter table t modify arr set('{\"obj\": 100}', '[-1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')", mysql.ErrUnsupportedDDLOperation)
 	tk.MustGetErrCode("alter table t modify nil set('{\"obj\": 100}', '[-1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')", mysql.ErrUnsupportedDDLOperation)
@@ -1458,12 +1473,13 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustGetErrCode("alter table t modify ui set('{\"obj\": 100}', '[-1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')", mysql.ErrUnsupportedDDLOperation)
 	tk.MustGetErrCode("alter table t modify f64 set('{\"obj\": 100}', '[-1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')", mysql.ErrUnsupportedDDLOperation)
 	tk.MustGetErrCode("alter table t modify str set('{\"obj\": 100}', '[-1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')", mysql.ErrUnsupportedDDLOperation)
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1] null true false -22 22 323232323.32323235 \"json string\""))
+	tk.MustGetErrCode("alter table t modify nul set('{\"obj\": 100}', '[-1]', 'null', 'true', 'false', '-22', '22', '323232323.3232323232', '\"json string\"')", mysql.ErrUnsupportedDDLOperation)
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1] null true false -22 22 323232323.32323235 \"json string\" <nil>"))
 
 	// To date and time data types.
 	// datetime
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '20200826173501', '20201123', '20200826173501.123456', '\"2020-08-26 17:35:01.123456\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '20200826173501', '20201123', '20200826173501.123456', '\"2020-08-26 17:35:01.123456\"', null)")
 	tk.MustGetErrCode("alter table t modify obj datetime", mysql.ErrTruncatedWrongValue)
 	tk.MustGetErrCode("alter table t modify arr datetime", mysql.ErrTruncatedWrongValue)
 	tk.MustGetErrCode("alter table t modify nil datetime", mysql.ErrTruncatedWrongValue)
@@ -1474,11 +1490,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify f64 datetime")
 	// MySQL will get "ERROR 1292 (22007): Incorrect datetime value: '"2020-08-26 17:35:01.123456"' for column 'str' at row 1".
 	tk.MustExec("alter table t modify str datetime")
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false 2020-08-26 17:35:01 2020-11-23 00:00:00 2020-08-26 17:35:01 2020-08-26 17:35:01"))
+	tk.MustExec("alter table t modify nul datetime")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false 2020-08-26 17:35:01 2020-11-23 00:00:00 2020-08-26 17:35:01 2020-08-26 17:35:01 <nil>"))
 
 	// time
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '200805', '1111', '200805.11', '\"19:35:41\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '200805', '1111', '200805.11', '\"19:35:41\"', null)")
 	// MySQL will get "ERROR 1366 (HY000): Incorrect time value: '{"obj": 100}' for column 'obj' at row 1".
 	tk.MustGetErrCode("alter table t modify obj time", mysql.ErrTruncatedWrongValue)
 	// MySQL will get "ERROR 1366 (HY000): Incorrect time value: '[-1, 0, 1]' for column 'arr' at row 11".
@@ -1494,11 +1511,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify f64 time")
 	// MySQL will get "ERROR 1292 (22007): Incorrect time value: '"19:35:41"' for column 'str' at row 1".
 	tk.MustExec("alter table t modify str time")
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false 20:08:05 00:11:11 20:08:05 19:35:41"))
+	tk.MustExec("alter table t modify nul time")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false 20:08:05 00:11:11 20:08:05 19:35:41 <nil>"))
 
 	// date
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '20200826173501', '20201123', '20200826173501.123456', '\"2020-08-26 17:35:01.123456\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '20200826173501', '20201123', '20200826173501.123456', '\"2020-08-26 17:35:01.123456\"', null)")
 	tk.MustGetErrCode("alter table t modify obj date", mysql.ErrTruncatedWrongValue)
 	tk.MustGetErrCode("alter table t modify arr date", mysql.ErrTruncatedWrongValue)
 	tk.MustGetErrCode("alter table t modify nil date", mysql.ErrTruncatedWrongValue)
@@ -1509,11 +1527,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify f64 date")
 	// MySQL will get "ERROR 1292 (22007): Incorrect date value: '"2020-08-26 17:35:01.123456"' for column 'str' at row 1".
 	tk.MustExec("alter table t modify str date")
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false 2020-08-26 2020-11-23 2020-08-26 2020-08-26"))
+	tk.MustExec("alter table t modify nul date")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false 2020-08-26 2020-11-23 2020-08-26 2020-08-26 <nil>"))
 
 	// timestamp
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '20200826173501', '20201123', '20200826173501.123456', '\"2020-08-26 17:35:01.123456\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '20200826173501', '20201123', '20200826173501.123456', '\"2020-08-26 17:35:01.123456\"', null)")
 	tk.MustGetErrCode("alter table t modify obj timestamp", mysql.ErrTruncatedWrongValue)
 	tk.MustGetErrCode("alter table t modify arr timestamp", mysql.ErrTruncatedWrongValue)
 	tk.MustGetErrCode("alter table t modify nil timestamp", mysql.ErrTruncatedWrongValue)
@@ -1524,11 +1543,12 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify f64 timestamp")
 	// MySQL will get "ERROR 1292 (22007): Incorrect timestamptime value: '"2020-08-26 17:35:01.123456"' for column 'str' at row 1".
 	tk.MustExec("alter table t modify str timestamp")
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false 2020-08-26 17:35:01 2020-11-23 00:00:00 2020-08-26 17:35:01 2020-08-26 17:35:01"))
+	tk.MustExec("alter table t modify nul timestamp")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null true false 2020-08-26 17:35:01 2020-11-23 00:00:00 2020-08-26 17:35:01 2020-08-26 17:35:01 <nil>"))
 
 	// year
 	reset(tk)
-	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '2020', '91', '9', '\"2020\"')")
+	tk.MustExec("insert into t values ('{\"obj\": 100}', '[-1, 0, 1]', 'null', 'true', 'false', '2020', '91', '9', '\"2020\"', null)")
 	// MySQL will get "ERROR 1366 (HY000): Incorrect integer value: '{"obj": 100}' for column 'obj' at row 1".
 	tk.MustGetErrCode("alter table t modify obj year", mysql.ErrTruncatedWrongValue)
 	// MySQL will get "ERROR 1366 (HY000): Incorrect integer value: '[-1, 0, 1]' for column 'arr' at row 11".
@@ -1544,7 +1564,8 @@ func (s *testColumnTypeChangeSuite) TestColumnTypeChangeFromJsonToOthers(c *C) {
 	tk.MustExec("alter table t modify f64 year")
 	// MySQL will get "ERROR 1366 (HY000): Incorrect integer value: '"2020"' for column 'str' at row 1".
 	tk.MustExec("alter table t modify str year")
-	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null 2001 0 2020 1991 2009 2020"))
+	tk.MustExec("alter table t modify nul year")
+	tk.MustQuery("select * from t").Check(testkit.Rows("{\"obj\": 100} [-1, 0, 1] null 2001 0 2020 1991 2009 2020 <nil>"))
 }
 
 func (s *testColumnTypeChangeSuite) TestUpdateDataAfterChangeTimestampToDate(c *C) {
diff --git a/executor/write_test.go b/executor/write_test.go
index 879c8c76c035f..b9095d8649cbd 100644
--- a/executor/write_test.go
+++ b/executor/write_test.go
@@ -2424,8 +2424,12 @@ func TestInsertCalculatedValue(t *testing.T) {
 
 	tk.MustExec("drop table if exists t")
 	tk.MustExec("create table t (a json not null, b int)")
+	tk.MustGetErrCode("insert into t value (a,a->'$')", mysql.ErrTruncatedWrongValueForField)
+
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t (a json not null, b varchar(10))")
 	tk.MustExec("insert into t value (a,a->'$')")
-	tk.MustQuery("select * from t").Check(testkit.Rows("null 0"))
+	tk.MustQuery("select * from t").Check(testkit.Rows("null null"))
 
 	tk.MustExec("drop table if exists t")
 	tk.MustExec("create table t(a json, b int, c int as (a->'$.a'))")