Revert "executor/show: show create table return utf8mb4 charset. (#8604)

ddl/ddl_api.go

@@ -989,10 +989,6 @@ func (d *ddl) CreateTable(ctx sessionctx.Context, s *ast.CreateTableStmt) (err e
 	if err != nil {
 		return errors.Trace(err)
 	}
-	if len(tbInfo.Charset) != 0 && strings.ToLower(tbInfo.Charset) != mysql.DefaultCharset {
-		ctx.GetSessionVars().StmtCtx.AppendWarning(errors.Errorf(`TiDB only supports the "utf8mb4" character set, so "%s" does not take effect.`, tbInfo.Charset))
-	}
-
 	err = d.doDDLJob(ctx, job)
 	if err == nil {
 		if tbInfo.AutoIncID > 1 {

executor/seqtest/seq_executor_test.go

@@ -179,7 +179,7 @@ func (s *seqTestSuite) TestShow(c *C) {
 	row := result.Rows()[0]
 	// For issue https://github.com/pingcap/tidb/issues/1061
 	expectedRow := []interface{}{
-		"SHOW_test", "CREATE TABLE `SHOW_test` (\n  `id` int(11) NOT NULL AUTO_INCREMENT,\n  `c1` int(11) DEFAULT NULL COMMENT 'c1_comment',\n  `c2` int(11) DEFAULT NULL,\n  `c3` int(11) DEFAULT '1',\n  `c4` text DEFAULT NULL,\n  `c5` tinyint(1) DEFAULT NULL,\n  PRIMARY KEY (`id`),\n  KEY `idx_wide_c4` (`c3`,`c4`(10))\n) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin AUTO_INCREMENT=28934 COMMENT='table_comment'"}
+		"SHOW_test", "CREATE TABLE `SHOW_test` (\n  `id` int(11) NOT NULL AUTO_INCREMENT,\n  `c1` int(11) DEFAULT NULL COMMENT 'c1_comment',\n  `c2` int(11) DEFAULT NULL,\n  `c3` int(11) DEFAULT '1',\n  `c4` text DEFAULT NULL,\n  `c5` tinyint(1) DEFAULT NULL,\n  PRIMARY KEY (`id`),\n  KEY `idx_wide_c4` (`c3`,`c4`(10))\n) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin AUTO_INCREMENT=28934 COMMENT='table_comment'"}
 	for i, r := range row {
 		c.Check(r, Equals, expectedRow[i])
 	}

executor/show.go

@@ -662,10 +662,24 @@ func (e *ShowExec) fetchShowCreateTable() error {
 	buf.WriteString("\n")
 
 	buf.WriteString(") ENGINE=InnoDB")
-	// Currently TiDB treat all the data as utf8mb4 actually.
-	// Make the TiDB's query result consistent with its actual behavior.
-	charsetName, collate := charset.GetDefaultCharsetAndCollate()
-	fmt.Fprintf(&buf, " DEFAULT CHARSET=%s COLLATE=%s", charsetName, collate)
+	charsetName := tb.Meta().Charset
+	if len(charsetName) == 0 {
+		charsetName = mysql.DefaultCharset
+	}
+	collate := tb.Meta().Collate
+	// Set default collate if collate is not specified.
+	if len(collate) == 0 {
+		collate = getDefaultCollate(charsetName)
+	}
+	// Because we only support case sensitive utf8_bin collate, we need to explicitly set the default charset and collation
+	// to make it work on MySQL server which has default collate utf8_general_ci.
+	if len(collate) == 0 {
+		// If we can not find default collate for the given charset,
+		// do not show the collate part.
+		fmt.Fprintf(&buf, " DEFAULT CHARSET=%s", charsetName)
+	} else {
+		fmt.Fprintf(&buf, " DEFAULT CHARSET=%s COLLATE=%s", charsetName, collate)
+	}
 
 	// Displayed if the compression typed is set.
 	if len(tb.Meta().Compression) != 0 {

executor/show_test.go

@@ -324,21 +324,3 @@ func (s *testSuite2) TestShowEscape(c *C) {
 	tk.MustExec("rename table \"t`abl\"\"e\" to t")
 	tk.MustExec("set sql_mode=@old_sql_mode")
 }
-
-func (s *testSuite) TestShowCreateTable(c *C) {
-	tk := testkit.NewTestKit(c, s.store)
-	tk.MustExec("use test")
-	tk.MustExec("drop table if exists t1,t2,t3")
-	tk.MustExec("create table t1 (a varchar(10));")
-	r := tk.MustQuery("show warnings")
-	c.Assert(len(r.Rows()), Equals, 0)
-	tk.MustExec("create table t2 (a varchar(10)) charset=UTF8mb4;")
-	r = tk.MustQuery("show warnings")
-	c.Assert(len(r.Rows()), Equals, 0)
-	tk.MustExec("create table t3 (a varchar(10)) charset=utf8;")
-	tk.MustQuery("show warnings").Check(testutil.RowsWithSep("|", `Warning|1105|TiDB only supports the "utf8mb4" character set, so "utf8" does not take effect.`))
-	tk.MustQuery("show create table t1;").Check(testutil.RowsWithSep("|", "t1|CREATE TABLE `t1` (\n  `a` varchar(10) DEFAULT NULL\n) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin"))
-	tk.MustQuery("show create table t2;").Check(testutil.RowsWithSep("|", "t2|CREATE TABLE `t2` (\n  `a` varchar(10) DEFAULT NULL\n) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin"))
-	tk.MustQuery("show create table t3;").Check(testutil.RowsWithSep("|", "t3|CREATE TABLE `t3` (\n  `a` varchar(10) DEFAULT NULL\n) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin"))
-	tk.MustExec("drop table t1,t2,t3")
-}