Fix set charset statement (pingcap#836)

ast/misc.go

@@ -561,9 +561,11 @@ func (n *UseStmt) Accept(v Visitor) (Node, bool) {
 }
 
 const (
-	// SetNames is the const for set names/charset stmt.
-	// If VariableAssignment.Name == Names, it should be set names/charset stmt.
+	// SetNames is the const for set names stmt.
+	// If VariableAssignment.Name == Names, it should be set names stmt.
 	SetNames = "SetNAMES"
+	// SetCharset is the const for set charset stmt.
+	SetCharset = "SetCharset"
 )
 
 // VariableAssignment is a variable assignment struct.
@@ -591,11 +593,13 @@ func (n *VariableAssignment) Restore(ctx *format.RestoreCtx) error {
 			ctx.WriteKeyWord("SESSION")
 		}
 		ctx.WritePlain(".")
-	} else if n.Name != SetNames {
+	} else if n.Name != SetNames && n.Name != SetCharset {
 		ctx.WriteKeyWord("@")
 	}
 	if n.Name == SetNames {
 		ctx.WriteKeyWord("NAMES ")
+	} else if n.Name == SetCharset {
+		ctx.WriteKeyWord("CHARSET ")
 	} else {
 		ctx.WriteName(n.Name)
 		ctx.WritePlain("=")

parser.y

@@ -8297,7 +8297,7 @@ VariableAssignment:
 	}
 |	CharsetKw CharsetNameOrDefault
 	{
-		$$ = &ast.VariableAssignment{Name: ast.SetNames, Value: $2}
+		$$ = &ast.VariableAssignment{Name: ast.SetCharset, Value: $2}
 	}
 
 CharsetNameOrDefault:

parser_test.go

@@ -1011,8 +1011,8 @@ func (s *testParserSuite) TestDBAStmt(c *C) {
 		{"SET @@global.autocommit = default", true, "SET @@GLOBAL.`autocommit`=DEFAULT"},
 		{"SET @@session.autocommit = default", true, "SET @@SESSION.`autocommit`=DEFAULT"},
 		// SET CHARACTER SET
-		{"SET CHARACTER SET utf8mb4;", true, "SET NAMES 'utf8mb4'"},
-		{"SET CHARACTER SET 'utf8mb4';", true, "SET NAMES 'utf8mb4'"},
+		{"SET CHARACTER SET utf8mb4;", true, "SET CHARSET 'utf8mb4'"},
+		{"SET CHARACTER SET 'utf8mb4';", true, "SET CHARSET 'utf8mb4'"},
 		// set password
 		{"SET PASSWORD = 'password';", true, "SET PASSWORD='password'"},
 		{"SET PASSWORD FOR 'root'@'localhost' = 'password';", true, "SET PASSWORD FOR `root`@`localhost`='password'"},
@@ -1037,9 +1037,9 @@ func (s *testParserSuite) TestDBAStmt(c *C) {
 
 		// for set character set | name default
 		{"set names default", true, "SET NAMES DEFAULT"},
-		{"set character set default", true, "SET NAMES DEFAULT"},
-		{"set charset default", true, "SET NAMES DEFAULT"},
-		{"set char set default", true, "SET NAMES DEFAULT"},
+		{"set character set default", true, "SET CHARSET DEFAULT"},
+		{"set charset default", true, "SET CHARSET DEFAULT"},
+		{"set char set default", true, "SET CHARSET DEFAULT"},
 
 		{"set role `role1`", true, "SET ROLE `role1`@`%`"},
 		{"SET ROLE DEFAULT", true, "SET ROLE DEFAULT"},
@@ -1048,7 +1048,7 @@ func (s *testParserSuite) TestDBAStmt(c *C) {
 		{"SET DEFAULT ROLE administrator, developer TO `joe`@`10.0.0.1`", true, "SET DEFAULT ROLE `administrator`@`%`, `developer`@`%` TO `joe`@`10.0.0.1`"},
 		// for set names and set vars
 		{"set names utf8, @@session.sql_mode=1;", true, "SET NAMES 'utf8', @@SESSION.`sql_mode`=1"},
-		{"set @@session.sql_mode=1, names utf8, charset utf8;", true, "SET @@SESSION.`sql_mode`=1, NAMES 'utf8', NAMES 'utf8'"},
+		{"set @@session.sql_mode=1, names utf8, charset utf8;", true, "SET @@SESSION.`sql_mode`=1, NAMES 'utf8', CHARSET 'utf8'"},
 
 		// for set/show config
 		{"set config TIKV LOG.LEVEL='info'", true, "SET CONFIG TIKV LOG.LEVEL = 'info'"},