From 74817dc70e35eefc890f3612ac7cc2304a26e10e Mon Sep 17 00:00:00 2001
From: dongyan <34701401+dyzsr@users.noreply.github.com>
Date: Thu, 3 Dec 2020 14:43:18 +0800
Subject: [PATCH] planner: report error when UPDATE set generated column with
 non-default value (#21460)

---
 planner/core/integration_test.go     | 19 +++++++++++++++++++
 planner/core/logical_plan_builder.go |  2 +-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/planner/core/integration_test.go b/planner/core/integration_test.go
index 72dfc8f47ec5c..03c10f82814c9 100644
--- a/planner/core/integration_test.go
+++ b/planner/core/integration_test.go
@@ -1918,6 +1918,25 @@ func (s *testIntegrationSuite) TestUpdateMultiUpdatePK(c *C) {
 	tk.MustQuery("SELECT * FROM t").Check(testkit.Rows("2 12"))
 }
 
+func (s *testIntegrationSuite) TestUpdateSetDefault(c *C) {
+	// #20598
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("create table tt (x int, z int as (x+10) stored)")
+	tk.MustExec("insert into tt(x) values (1)")
+	tk.MustExec("update tt set x=2, z = default")
+	tk.MustQuery("select * from tt").Check(testkit.Rows("2 12"))
+
+	tk.MustGetErrMsg("update tt set z = 123",
+		"[planner:3105]The value specified for generated column 'z' in table 'tt' is not allowed.")
+	tk.MustGetErrMsg("update tt as ss set z = 123",
+		"[planner:3105]The value specified for generated column 'z' in table 'tt' is not allowed.")
+	tk.MustGetErrMsg("update tt as ss set x = 3, z = 13",
+		"[planner:3105]The value specified for generated column 'z' in table 'tt' is not allowed.")
+	tk.MustGetErrMsg("update tt as s1, tt as s2 set s1.z = default, s2.z = 456",
+		"[planner:3105]The value specified for generated column 'z' in table 'tt' is not allowed.")
+}
+
 func (s *testIntegrationSerialSuite) TestPreferRangeScan(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
diff --git a/planner/core/logical_plan_builder.go b/planner/core/logical_plan_builder.go
index 520191f19efb8..e02e46dee1dab 100644
--- a/planner/core/logical_plan_builder.go
+++ b/planner/core/logical_plan_builder.go
@@ -3895,7 +3895,7 @@ func (b *PlanBuilder) buildUpdateLists(
 			if !colInfo.IsGenerated() {
 				continue
 			}
-			columnFullName := fmt.Sprintf("%s.%s.%s", tn.Schema.L, tn.Name.L, colInfo.Name.L)
+			columnFullName := fmt.Sprintf("%s.%s.%s", tn.DBInfo.Name.L, tn.Name.L, colInfo.Name.L)
 			isDefault, ok := modifyColumns[columnFullName]
 			if ok && colInfo.Hidden {
 				return nil, nil, false, ErrUnknownColumn.GenWithStackByArgs(colInfo.Name, clauseMsg[fieldList])