ddl, executor, server: add drop if exists warnings (#14807)

Author: 0xPoe

ddl/sequence_test.go

@@ -152,6 +152,10 @@ func (s *testSequenceSuite) TestDropSequence(c *C) {
 	_, err = tk1.Exec("drop sequence my_seq")
 	c.Assert(err, NotNil)
 	c.Assert(err.Error(), Equals, "[planner:1142]DROP command denied to user 'localhost'@'myuser' for table 'my_seq'")
+
+	// Test for `drop sequence if exists`.
+	s.tk.MustExec("drop sequence if exists seq_if_exists")
+	s.tk.MustQuery("show warnings;").Check(testkit.Rows("Note 4139 Unknown SEQUENCE: 'test.seq_if_exists'"))
 }
 
 func (s *testSequenceSuite) TestShowCreateSequence(c *C) {

executor/ddl.go

@@ -334,6 +334,16 @@ func (e *DDLExec) dropTableObject(objects []*ast.TableName, obt objectType, ifEx
 		}
 		return infoschema.ErrTableDropExists.GenWithStackByArgs(strings.Join(notExistTables, ","))
 	}
+	// We need add warning when use if exists.
+	if len(notExistTables) > 0 && ifExists {
+		for _, table := range notExistTables {
+			if obt == sequenceObject {
+				e.ctx.GetSessionVars().StmtCtx.AppendNote(infoschema.ErrSequenceDropExists.GenWithStackByArgs(table))
+			} else {
+				e.ctx.GetSessionVars().StmtCtx.AppendNote(infoschema.ErrTableDropExists.GenWithStackByArgs(table))
+			}
+		}
+	}
 	return nil
 }
 

executor/ddl_test.go

@@ -173,6 +173,13 @@ func (s *testSuite6) TestCreateTable(c *C) {
 	tk.MustExec("insert into create_auto_increment_test (name) values ('aa')")
 	r = tk.MustQuery("select * from create_auto_increment_test;")
 	r.Check(testkit.Rows("1000 aa"))
+
+	// Test for `drop table if exists`.
+	tk.MustExec("drop table if exists t_if_exists;")
+	tk.MustQuery("show warnings;").Check(testkit.Rows("Note 1051 Unknown table 'test.t_if_exists'"))
+	tk.MustExec("create table if not exists t1_if_exists(c int)")
+	tk.MustExec("drop table if exists t1_if_exists,t2_if_exists,t3_if_exists")
+	tk.MustQuery("show warnings").Check(testutil.RowsWithSep("|", "Note|1051|Unknown table 'test.t2_if_exists'", "Note|1051|Unknown table 'test.t3_if_exists'"))
 }
 
 func (s *testSuite6) TestCreateView(c *C) {
@@ -253,6 +260,13 @@ func (s *testSuite6) TestCreateView(c *C) {
 	tk.MustExec("drop view v")
 	tk.MustExec("create view v as (select * from t1 union select * from t2)")
 	tk.MustExec("drop view v")
+
+	// Test for `drop view if exists`.
+	tk.MustExec("drop view if exists v_if_exists;")
+	tk.MustQuery("show warnings;").Check(testkit.Rows("Note 1051 Unknown table 'test.v_if_exists'"))
+	tk.MustExec("create view v1_if_exists as (select * from t1)")
+	tk.MustExec("drop view if exists v1_if_exists,v2_if_exists,v3_if_exists")
+	tk.MustQuery("show warnings").Check(testutil.RowsWithSep("|", "Note|1051|Unknown table 'test.v2_if_exists'", "Note|1051|Unknown table 'test.v3_if_exists'"))
 }
 
 func (s *testSuite6) TestCreateDropDatabase(c *C) {

server/http_handler_test.go

@@ -30,6 +30,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	dmysql "github.com/go-sql-driver/mysql"
 	. "github.com/pingcap/check"
 	"github.com/pingcap/failpoint"
 	zaplog "github.com/pingcap/log"
@@ -927,7 +928,10 @@ func (ts *HTTPHandlerTestSuite) TestPostSettings(c *C) {
 	c.Assert(atomic.LoadUint32(&variable.DDLSlowOprThreshold), Equals, uint32(200))
 
 	// test check_mb4_value_in_utf8
-	db, err := sql.Open("mysql", ts.getDSN())
+	overriders := []configOverrider{func(config *dmysql.Config) {
+		config.Strict = false
+	}}
+	db, err := sql.Open("mysql", ts.getDSN(overriders...))
 	c.Assert(err, IsNil, Commentf("Error connecting"))
 	defer db.Close()
 	dbt := &DBTest{c, db}

server/server_test.go

@@ -791,7 +791,9 @@ func (cli *testServerClient) runTestLoadData(c *C, server *Server) {
 
 func (cli *testServerClient) runTestConcurrentUpdate(c *C) {
 	dbName := "Concurrent"
-	cli.runTestsOnNewDB(c, nil, dbName, func(dbt *DBTest) {
+	cli.runTestsOnNewDB(c, func(config *mysql.Config) {
+		config.Strict = false
+	}, dbName, func(dbt *DBTest) {
 		dbt.mustExec("drop table if exists test2")
 		dbt.mustExec("create table test2 (a int, b int)")
 		dbt.mustExec("insert test2 values (1, 1)")
@@ -1014,7 +1016,9 @@ func (cli *testServerClient) runTestDBNameEscape(c *C) {
 }
 
 func (cli *testServerClient) runTestResultFieldTableIsNull(c *C) {
-	cli.runTestsOnNewDB(c, nil, "ResultFieldTableIsNull", func(dbt *DBTest) {
+	cli.runTestsOnNewDB(c, func(config *mysql.Config) {
+		config.Strict = false
+	}, "ResultFieldTableIsNull", func(dbt *DBTest) {
 		dbt.mustExec("drop table if exists test;")
 		dbt.mustExec("create table test (c int);")
 		dbt.mustExec("explain select * from test;")