executor: query user and role, hostname should be lowercase (#28880)

executor/simple.go

@@ -1302,7 +1302,7 @@ func (e *SimpleExec) executeDropUser(ctx context.Context, s *ast.DropUserStmt) e
 
 func userExists(ctx context.Context, sctx sessionctx.Context, name string, host string) (bool, error) {
 	exec := sctx.(sqlexec.RestrictedSQLExecutor)
-	stmt, err := exec.ParseWithParams(ctx, `SELECT * FROM %n.%n WHERE User=%? AND Host=%?;`, mysql.SystemDB, mysql.UserTable, name, host)
+	stmt, err := exec.ParseWithParams(ctx, `SELECT * FROM %n.%n WHERE User=%? AND Host=%?;`, mysql.SystemDB, mysql.UserTable, name, strings.ToLower(host))
 	if err != nil {
 		return false, err
 	}
@@ -1316,7 +1316,7 @@ func userExists(ctx context.Context, sctx sessionctx.Context, name string, host
 // use the same internal executor to read within the same transaction, otherwise same as userExists
 func userExistsInternal(sqlExecutor sqlexec.SQLExecutor, name string, host string) (bool, error) {
 	sql := new(strings.Builder)
-	sqlexec.MustFormatSQL(sql, `SELECT * FROM %n.%n WHERE User=%? AND Host=%?;`, mysql.SystemDB, mysql.UserTable, name, host)
+	sqlexec.MustFormatSQL(sql, `SELECT * FROM %n.%n WHERE User=%? AND Host=%?;`, mysql.SystemDB, mysql.UserTable, name, strings.ToLower(host))
 	recordSet, err := sqlExecutor.ExecuteInternal(context.TODO(), sql.String())
 	if err != nil {
 		return false, err

executor/simple_test.go

@@ -496,6 +496,25 @@ func (s *testSuite7) TestUser(c *C) {
 	tk.MustExec(renameUserSQL)
 	querySQL = `select user,host from mysql.user where user = 'userD';`
 	tk.MustQuery(querySQL).Check(testkit.Rows("userD demo.com"))
+
+	tk.MustExec(`create user joan;`)
+	tk.MustExec(`create user sally;`)
+	tk.MustExec(`create role engineering;`)
+	tk.MustExec(`create role consultants;`)
+	tk.MustExec(`create role qa;`)
+	tk.MustExec(`grant engineering to joan;`)
+	tk.MustExec(`grant engineering to sally;`)
+	tk.MustExec(`grant engineering, consultants to joan, sally;`)
+	tk.MustExec(`grant qa to consultants;`)
+	tk.MustExec("CREATE ROLE `engineering`@`US`;")
+	tk.MustExec("create role `engineering`@`INDIA`;")
+	_, err = tk.Exec("grant `engineering`@`US` TO `engineering`@`INDIA`;")
+	c.Check(err, IsNil)
+
+	tk.MustQuery("select user,host from mysql.user where user='engineering' and host = 'india'").
+		Check(testkit.Rows("engineering india"))
+	tk.MustQuery("select user,host from mysql.user where user='engineering' and host = 'us'").
+		Check(testkit.Rows("engineering us"))
 }
 
 func (s *testSuite3) TestSetPwd(c *C) {