executor:adjust 'show create table' for mysql compatibility (#9113)

cherry-pick for release 2.1

ddl/db_test.go

@@ -2238,7 +2238,7 @@ func (s *testDBSuite) TestGeneratedColumnDDL(c *C) {
 	result = s.tk.MustQuery(`show create table table_with_gen_col_blanks`)
 	result.Check(testkit.Rows("table_with_gen_col_blanks CREATE TABLE `table_with_gen_col_blanks` (\n" +
 		"  `a` int(11) DEFAULT NULL,\n" +
-		"  `b` char(20) CHARSET utf8mb4 COLLATE utf8mb4_bin GENERATED ALWAYS AS (CAST(`a` AS CHAR)) VIRTUAL DEFAULT NULL\n" +
+		"  `b` char(20) GENERATED ALWAYS AS (CAST(`a` AS CHAR)) VIRTUAL DEFAULT NULL\n" +
 		") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin"))
 
 	genExprTests := []struct {
@@ -2389,7 +2389,7 @@ func (s *testDBSuite) TestCheckColumnDefaultValue(c *C) {
 	s.tk.MustExec("create table text_default_text(c1 text not null default '');")
 	s.tk.MustQuery(`show create table text_default_text`).Check(testutil.RowsWithSep("|",
 		"text_default_text CREATE TABLE `text_default_text` (\n"+
-			"  `c1` text CHARSET utf8mb4 COLLATE utf8mb4_bin NOT NULL\n"+
+			"  `c1` text NOT NULL\n"+
 			") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin",
 	))
 	ctx := s.tk.Se.(sessionctx.Context)

executor/ddl_test.go

@@ -233,7 +233,7 @@ func (s *testSuite) TestAlterTableModifyColumn(c *C) {
 	tk.MustExec("alter table mc modify column c2 text")
 	result := tk.MustQuery("show create table mc")
 	createSQL := result.Rows()[0][1]
-	expected := "CREATE TABLE `mc` (\n  `c1` bigint(20) DEFAULT NULL,\n  `c2` text CHARSET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL\n) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin"
+	expected := "CREATE TABLE `mc` (\n  `c1` bigint(20) DEFAULT NULL,\n  `c2` text DEFAULT NULL\n) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin"
 	c.Assert(createSQL, Equals, expected)
 }
 

executor/show.go

@@ -492,13 +492,31 @@ func (e *ShowExec) fetchShowCreateTable() error {
 
 	// TODO: let the result more like MySQL.
 	var buf bytes.Buffer
-	buf.WriteString(fmt.Sprintf("CREATE TABLE %s (\n", escape(tb.Meta().Name, sqlMode)))
+	if tb.Meta().IsView() {
+		e.fetchShowCreateTable4View(tb.Meta(), &buf)
+		e.appendRow([]interface{}{tb.Meta().Name.O, buf.String(), tb.Meta().Charset, tb.Meta().Collate})
+		return nil
+	}
+
+	tblCharset := tb.Meta().Charset
+	if len(tblCharset) == 0 {
+		tblCharset = mysql.DefaultCharset
+	}
+	tblCollate := tb.Meta().Collate
+	// Set default collate if collate is not specified.
+	if len(tblCollate) == 0 {
+		tblCollate = getDefaultCollate(tblCharset)
+	}
+
+	fmt.Fprintf(&buf, "CREATE TABLE %s (\n", escape(tb.Meta().Name, sqlMode))
 	var pkCol *table.Column
 	var hasAutoIncID bool
 	for i, col := range tb.Cols() {
 		buf.WriteString(fmt.Sprintf("  %s %s", escape(col.Name, sqlMode), col.GetTypeDesc()))
 		if col.Charset != "binary" {
-			fmt.Fprintf(&buf, " CHARSET %s COLLATE %s", col.Charset, col.Collate)
+			if col.Charset != tblCharset || col.Collate != tblCollate {
+				fmt.Fprintf(&buf, " CHARSET %s COLLATE %s", col.Charset, col.Collate)
+			}
 		}
 		if col.IsGenerated() {
 			// It's a generated column.
@@ -596,23 +614,14 @@ func (e *ShowExec) fetchShowCreateTable() error {
 	buf.WriteString("\n")
 
 	buf.WriteString(") ENGINE=InnoDB")
-	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 len(tblCollate) == 0 {
 		// If we can not find default collate for the given charset,
 		// do not show the collate part.
-		buf.WriteString(fmt.Sprintf(" DEFAULT CHARSET=%s", charsetName))
+		fmt.Fprintf(&buf, " DEFAULT CHARSET=%s", tblCharset)
 	} else {
-		buf.WriteString(fmt.Sprintf(" DEFAULT CHARSET=%s COLLATE=%s", charsetName, collate))
+		fmt.Fprintf(&buf, " DEFAULT CHARSET=%s COLLATE=%s", tblCharset, tblCollate)
 	}
 
 	// Displayed if the compression typed is set.

executor/show_test.go

@@ -669,7 +669,32 @@ func (s *testSuite) TestShowSlow(c *C) {
 	tk.MustQuery(`admin show slow top all 3`)
 }
 
-func (s *testSuite) TestShowEscape(c *C) {
+func (s *testSuite2) TestShowCreateTable(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t1")
+	tk.MustExec("create table t1(a int,b int)")
+	tk.MustExec("drop view if exists v1")
+	tk.MustExec("create or replace definer=`root`@`127.0.0.1` view v1 as select * from t1")
+	tk.MustQuery("show create table v1").Check(testutil.RowsWithSep("|", "v1|CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`127.0.0.1` SQL SECURITY DEFINER VIEW `v1` (`a`, `b`) AS select * from t1  "))
+
+	tk.MustExec("drop view v1")
+	tk.MustExec("drop table t1")
+
+	tk.MustExec(`drop table if exists different_charset`)
+	tk.MustExec(`create table different_charset(ch1 varchar(10) charset utf8, ch2 varchar(10) charset binary);`)
+	tk.MustQuery(`show create table different_charset`).Check(testutil.RowsWithSep("|",
+		""+
+			"different_charset CREATE TABLE `different_charset` (\n"+
+			"  `ch1` varchar(10) CHARSET utf8 COLLATE utf8_bin DEFAULT NULL,\n"+
+			"  `ch2` varbinary(10) DEFAULT NULL\n"+
+			") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin",
+	))
+
+}
+
+func (s *testSuite2) TestShowEscape(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 
 	tk.MustExec("use test")