executor, infoschema: fix display of on update CURRENT_TIMESTAMP with decimal

ddl/db_integration_test.go

@@ -416,6 +416,14 @@ func (s *testIntegrationSuite5) TestMySQLErrorCode(c *C) {
 	assertErrorCode(c, tk, sql, tmysql.ErrPrimaryCantHaveNull)
 	sql = "create table t2 (id int auto_increment);"
 	assertErrorCode(c, tk, sql, tmysql.ErrWrongAutoKey)
+	sql = "create table t2 (a datetime(2) default current_timestamp(3))"
+	assertErrorCode(c, tk, sql, tmysql.ErrInvalidDefault)
+	sql = "create table t2 (a datetime(2) default current_timestamp(2) on update current_timestamp)"
+	assertErrorCode(c, tk, sql, tmysql.ErrInvalidOnUpdate)
+	sql = "create table t2 (a datetime default current_timestamp on update current_timestamp(2))"
+	assertErrorCode(c, tk, sql, tmysql.ErrInvalidOnUpdate)
+	sql = "create table t2 (a datetime(2) default current_timestamp(2) on update current_timestamp(3))"
+	assertErrorCode(c, tk, sql, tmysql.ErrInvalidOnUpdate)
 
 	sql = "create table t2 (id int primary key , age int);"
 	tk.MustExec(sql)

ddl/ddl_api.go

@@ -540,7 +540,7 @@ func columnDefToCol(ctx sessionctx.Context, offset int, colDef *ast.ColumnDef, o
 			case ast.ColumnOptionOnUpdate:
 				// TODO: Support other time functions.
 				if col.Tp == mysql.TypeTimestamp || col.Tp == mysql.TypeDatetime {
-					if !expression.IsCurrentTimestampExpr(v.Expr) {
+					if !expression.IsValidCurrentTimestampExpr(v.Expr, colDef.Tp) {
 						return nil, nil, ErrInvalidOnUpdate.GenWithStackByArgs(col.Name)
 					}
 				} else {
@@ -2527,7 +2527,7 @@ func processColumnOptions(ctx sessionctx.Context, col *table.Column, options []*
 		case ast.ColumnOptionOnUpdate:
 			// TODO: Support other time functions.
 			if col.Tp == mysql.TypeTimestamp || col.Tp == mysql.TypeDatetime {
-				if !expression.IsCurrentTimestampExpr(opt.Expr) {
+				if !expression.IsValidCurrentTimestampExpr(opt.Expr, &col.FieldType) {
 					return ErrInvalidOnUpdate.GenWithStackByArgs(col.Name)
 				}
 			} else {

executor/show.go

@@ -721,6 +721,7 @@ func (e *ShowExec) fetchShowCreateTable() error {
 			}
 			if mysql.HasOnUpdateNowFlag(col.Flag) {
 				buf.WriteString(" ON UPDATE CURRENT_TIMESTAMP")
+				buf.WriteString(table.OptionalFsp(&col.FieldType))
 			}
 		}
 		if len(col.Comment) > 0 {

executor/show_test.go

@@ -198,6 +198,7 @@ func (s *testSuite2) TestShow2(c *C) {
 					c_timestamp timestamp,
 					c_timestamp_default timestamp default current_timestamp,
 					c_timestamp_default_3 timestamp(3) default current_timestamp(3),
+					c_timestamp_default_4 timestamp(3) default current_timestamp(3) on update current_timestamp(3),
 					c_blob blob,
 					c_tinyblob tinyblob,
 					c_mediumblob mediumblob,
@@ -233,6 +234,7 @@ func (s *testSuite2) TestShow2(c *C) {
 			"[c_timestamp timestamp <nil> YES  <nil>  select,insert,update,references ]\n" +
 			"[c_timestamp_default timestamp <nil> YES  CURRENT_TIMESTAMP  select,insert,update,references ]\n" +
 			"[c_timestamp_default_3 timestamp(3) <nil> YES  CURRENT_TIMESTAMP(3)  select,insert,update,references ]\n" +
+			"[c_timestamp_default_4 timestamp(3) <nil> YES  CURRENT_TIMESTAMP(3) DEFAULT_GENERATED on update CURRENT_TIMESTAMP(3) select,insert,update,references ]\n" +
 			"[c_blob blob <nil> YES  <nil>  select,insert,update,references ]\n" +
 			"[c_tinyblob tinyblob <nil> YES  <nil>  select,insert,update,references ]\n" +
 			"[c_mediumblob mediumblob <nil> YES  <nil>  select,insert,update,references ]\n" +
@@ -488,15 +490,19 @@ func (s *testSuite2) TestShowCreateTable(c *C) {
 		"`b` timestamp(3) default current_timestamp(3),\n" +
 		"`c` datetime default current_timestamp,\n" +
 		"`d` datetime(4) default current_timestamp(4),\n" +
-		"`e` varchar(20) default 'cUrrent_tImestamp')")
+		"`e` varchar(20) default 'cUrrent_tImestamp',\n" +
+		"`f` datetime(2) default current_timestamp(2) on update current_timestamp(2),\n" +
+		"`g` timestamp(2) default current_timestamp(2) on update current_timestamp(2))")
 	tk.MustQuery("show create table `t`").Check(testutil.RowsWithSep("|",
 		""+
 			"t CREATE TABLE `t` (\n"+
 			"  `a` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,\n"+
 			"  `b` timestamp(3) DEFAULT CURRENT_TIMESTAMP(3),\n"+
 			"  `c` datetime DEFAULT CURRENT_TIMESTAMP,\n"+
 			"  `d` datetime(4) DEFAULT CURRENT_TIMESTAMP(4),\n"+
-			"  `e` varchar(20) DEFAULT 'cUrrent_tImestamp'\n"+
+			"  `e` varchar(20) DEFAULT 'cUrrent_tImestamp',\n"+
+			"  `f` datetime(2) DEFAULT CURRENT_TIMESTAMP(2) ON UPDATE CURRENT_TIMESTAMP(2),\n"+
+			"  `g` timestamp(2) DEFAULT CURRENT_TIMESTAMP(2) ON UPDATE CURRENT_TIMESTAMP(2)\n"+
 			") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin",
 	))
 	tk.MustExec("drop table t")

expression/helper.go

@@ -34,12 +34,24 @@ func boolToInt64(v bool) int64 {
 	return 0
 }
 
-// IsCurrentTimestampExpr returns whether e is CurrentTimestamp expression.
-func IsCurrentTimestampExpr(e ast.ExprNode) bool {
-	if fn, ok := e.(*ast.FuncCallExpr); ok && fn.FnName.L == ast.CurrentTimestamp {
-		return true
+// IsValidCurrentTimestampExpr returns true if exprNode is a valid CurrentTimestamp expression.
+// Here `valid` means it is consistent with the given fieldType's Decimal.
+func IsValidCurrentTimestampExpr(exprNode ast.ExprNode, fieldType *types.FieldType) bool {
+	fn, isFuncCall := exprNode.(*ast.FuncCallExpr)
+	if !isFuncCall || fn.FnName.L != ast.CurrentTimestamp {
+		return false
 	}
-	return false
+
+	containsArg := len(fn.Args) > 0
+	// Fsp represents fractional seconds precision.
+	containsFsp := fieldType != nil && fieldType.Decimal > 0
+	var isConsistent bool
+	if containsArg {
+		v, ok := fn.Args[0].(*driver.ValueExpr)
+		isConsistent = ok && fieldType != nil && v.Datum.GetInt64() == int64(fieldType.Decimal)
+	}
+
+	return (containsArg && isConsistent) || (!containsArg && !containsFsp)
 }
 
 // GetTimeValue gets the time value with type tp.

expression/helper_test.go

@@ -14,6 +14,7 @@
 package expression
 
 import (
+	driver "github.com/pingcap/tidb/types/parser_driver"
 	"strings"
 	"time"
 
@@ -108,11 +109,28 @@ func (s *testExpressionSuite) TestGetTimeValue(c *C) {
 
 func (s *testExpressionSuite) TestIsCurrentTimestampExpr(c *C) {
 	defer testleak.AfterTest(c)()
-	v := IsCurrentTimestampExpr(ast.NewValueExpr("abc"))
-	c.Assert(v, IsFalse)
+	buildTimestampFuncCallExpr := func(i int64) *ast.FuncCallExpr {
+		var args []ast.ExprNode
+		if i != 0 {
+			args = []ast.ExprNode{&driver.ValueExpr{Datum: types.NewIntDatum(i)}}
+		}
+		return &ast.FuncCallExpr{FnName: model.NewCIStr("CURRENT_TIMESTAMP"), Args: args}
+	}
 
-	v = IsCurrentTimestampExpr(&ast.FuncCallExpr{FnName: model.NewCIStr("CURRENT_TIMESTAMP")})
+	v := IsValidCurrentTimestampExpr(ast.NewValueExpr("abc"), nil)
+	c.Assert(v, IsFalse)
+	v = IsValidCurrentTimestampExpr(buildTimestampFuncCallExpr(0), nil)
+	c.Assert(v, IsTrue)
+	v = IsValidCurrentTimestampExpr(buildTimestampFuncCallExpr(3), &types.FieldType{Decimal: 3})
 	c.Assert(v, IsTrue)
+	v = IsValidCurrentTimestampExpr(buildTimestampFuncCallExpr(1), &types.FieldType{Decimal: 3})
+	c.Assert(v, IsFalse)
+	v = IsValidCurrentTimestampExpr(buildTimestampFuncCallExpr(0), &types.FieldType{Decimal: 3})
+	c.Assert(v, IsFalse)
+	v = IsValidCurrentTimestampExpr(buildTimestampFuncCallExpr(2), &types.FieldType{Decimal: 0})
+	c.Assert(v, IsFalse)
+	v = IsValidCurrentTimestampExpr(buildTimestampFuncCallExpr(2), nil)
+	c.Assert(v, IsFalse)
 }
 
 func (s *testExpressionSuite) TestCurrentTimestampTimeZone(c *C) {

table/column.go

@@ -19,6 +19,7 @@ package table
 
 import (
 	"fmt"
+	"strconv"
 	"strings"
 	"time"
 	"unicode/utf8"
@@ -271,7 +272,7 @@ func NewColDesc(col *Column) *ColDesc {
 	} else if mysql.HasOnUpdateNowFlag(col.Flag) {
 		//in order to match the rules of mysql 8.0.16 version
 		//see https://github.com/pingcap/tidb/issues/10337
-		extra = "DEFAULT_GENERATED on update CURRENT_TIMESTAMP"
+		extra = "DEFAULT_GENERATED on update CURRENT_TIMESTAMP" + OptionalFsp(&col.FieldType)
 	} else if col.IsGenerated() {
 		if col.GeneratedStored {
 			extra = "STORED GENERATED"
@@ -490,3 +491,12 @@ func GetZeroValue(col *model.ColumnInfo) types.Datum {
 	}
 	return d
 }
+
+// OptionalFsp convert a FieldType.Decimal to string.
+func OptionalFsp(fieldType *types.FieldType) string {
+	fsp := fieldType.Decimal
+	if fsp == 0 {
+		return ""
+	}
+	return "(" + strconv.Itoa(fsp) + ")"
+}