ddl: check foreign key constraint when drop,modify,change column

ddl/column.go

@@ -535,6 +535,17 @@ func isColumnWithIndex(colName string, indices []*model.IndexInfo) bool {
 	return false
 }
 
+func isColumnWithForeignKey(colName string, fkInfos []*model.FKInfo) *model.FKInfo {
+	for _, fkInfo := range fkInfos {
+		for _, col := range fkInfo.Cols {
+			if col.L == colName {
+				return fkInfo
+			}
+		}
+	}
+	return nil
+}
+
 func allocateColumnID(tblInfo *model.TableInfo) int64 {
 	tblInfo.MaxColumnID++
 	return tblInfo.MaxColumnID

ddl/db_test.go

@@ -2306,7 +2306,18 @@ func (s *testDBSuite2) TestTableForeignKey(c *C) {
 	// test oreign key not match error
 	failSQL = "alter table t1 add foreign key (a) REFERENCES t3(a, b);"
 	s.tk.MustGetErrCode(failSQL, mysql.ErrWrongFkDef)
-	s.tk.MustExec("drop table if exists t1,t2,t3;")
+	// Test drop column with foreign key.
+	s.tk.MustExec("create table t4 (c int,d int,foreign key (d) references t1 (b));")
+	failSQL = "alter table t4 drop column d"
+	s.tk.MustGetErrCode(failSQL, mysql.ErrFkColumnCannotDrop)
+	// Test change column with foreign key.
+	failSQL = "alter table t4 change column d e bigint;"
+	s.tk.MustGetErrCode(failSQL, mysql.ErrReferencedForeignKey)
+	// Test modify column with foreign key.
+	failSQL = "alter table t4 modify column d bigint;"
+	s.tk.MustGetErrCode(failSQL, mysql.ErrReferencedForeignKey)
+	s.tk.MustQuery("select count(*) from information_schema.KEY_COLUMN_USAGE;")
+	s.tk.MustExec("drop table if exists t1,t2,t3,t4;")
 }
 
 func (s *testDBSuite3) TestFKOnGeneratedColumns(c *C) {

ddl/ddl.go

@@ -107,6 +107,8 @@ var (
 	errTooManyFields            = terror.ClassDDL.New(mysql.ErrTooManyFields, mysql.MySQLErrName[mysql.ErrTooManyFields])
 	errInvalidSplitRegionRanges = terror.ClassDDL.New(mysql.ErrInvalidSplitRegionRanges, mysql.MySQLErrName[mysql.ErrInvalidSplitRegionRanges])
 	errReorgPanic               = terror.ClassDDL.New(mysql.ErrReorgPanic, mysql.MySQLErrName[mysql.ErrReorgPanic])
+	errFkColumnCannotDrop       = terror.ClassDDL.New(mysql.ErrFkColumnCannotDrop, mysql.MySQLErrName[mysql.ErrFkColumnCannotDrop])
+	errReferencedForeignKey     = terror.ClassDDL.New(mysql.ErrReferencedForeignKey, mysql.MySQLErrName[mysql.ErrReferencedForeignKey])
 
 	errOnlyOnRangeListPartition = terror.ClassDDL.New(mysql.ErrOnlyOnRangeListPartition, mysql.MySQLErrName[mysql.ErrOnlyOnRangeListPartition])
 	// errWrongKeyColumn is for table column cannot be indexed.
@@ -727,6 +729,8 @@ func init() {
 		mysql.ErrWrongTableName:                       mysql.ErrWrongTableName,
 		mysql.ErrWrongTypeColumnValue:                 mysql.ErrWrongTypeColumnValue,
 		mysql.WarnDataTruncated:                       mysql.WarnDataTruncated,
+		mysql.ErrFkColumnCannotDrop:                   mysql.ErrFkColumnCannotDrop,
+		mysql.ErrReferencedForeignKey:                 mysql.ErrReferencedForeignKey,
 	}
 	terror.ErrClassToMySQLCodes[terror.ClassDDL] = ddlMySQLErrCodes
 }

ddl/ddl_api.go

@@ -2638,6 +2638,10 @@ func (d *ddl) getModifiableColumnJob(ctx sessionctx.Context, ident ast.Ident, or
 			return nil, infoschema.ErrColumnExists.GenWithStackByArgs(newColName)
 		}
 	}
+	// Check the column with foreign key.
+	if fkInfo := isColumnWithForeignKey(originalColName.L, t.Meta().ForeignKeys); fkInfo != nil {
+		return nil, errReferencedForeignKey.GenWithStackByArgs(originalColName, fkInfo.Name)
+	}
 
 	// Constraints in the new column means adding new constraints. Errors should thrown,
 	// which will be done by `processColumnOptions` later.
@@ -3650,6 +3654,10 @@ func isDroppableColumn(tblInfo *model.TableInfo, colName model.CIStr) error {
 	if isColumnWithIndex(colName.L, tblInfo.Indices) {
 		return errCantDropColWithIndex.GenWithStack("can't drop column %s with index covered now", colName)
 	}
+	// Check the column with foreign key.
+	if fkInfo := isColumnWithForeignKey(colName.L, tblInfo.ForeignKeys); fkInfo != nil {
+		return errFkColumnCannotDrop.GenWithStackByArgs(colName, fkInfo.Name)
+	}
 	return nil
 }
 

go.mod

@@ -78,3 +78,5 @@ require (
 go 1.13
 
 replace github.com/pingcap/check => github.com/tiancaiamao/check v0.0.0-20191119042138-8e73d07b629d
+
+replace github.com/pingcap/parser => github.com/crazycs520/parser v0.0.0-20191212113323-e9031788820f

go.sum

@@ -29,6 +29,8 @@ github.com/coreos/go-systemd v0.0.0-20181031085051-9002847aa142/go.mod h1:F5haX7
 github.com/coreos/pkg v0.0.0-20160727233714-3ac0863d7acf/go.mod h1:E3G3o1h8I7cfcXa63jLwjI0eiQQMgzzUDFVpN/nH/eA=
 github.com/coreos/pkg v0.0.0-20180928190104-399ea9e2e55f h1:lBNOc5arjvs8E5mO2tbpBpLoyyu8B6e44T7hJy6potg=
 github.com/coreos/pkg v0.0.0-20180928190104-399ea9e2e55f/go.mod h1:E3G3o1h8I7cfcXa63jLwjI0eiQQMgzzUDFVpN/nH/eA=
+github.com/crazycs520/parser v0.0.0-20191212113323-e9031788820f h1:FrTWTCoxKNuK6hRhJbEiG67eHV4yOAjf3BHUpMa/vyk=
+github.com/crazycs520/parser v0.0.0-20191212113323-e9031788820f/go.mod h1:xLjI+gnWYexq011WPMEvCNS8rFM9qe1vdojIEzSKPuc=
 github.com/creack/pty v1.1.7/go.mod h1:lj5s0c3V2DBrqTV7llrYr5NG6My20zk30Fl46Y7DoTY=
 github.com/cznic/mathutil v0.0.0-20181122101859-297441e03548 h1:iwZdTE0PVqJCos1vaoKsclOGD3ADKpshg3SRtYBbwso=
 github.com/cznic/mathutil v0.0.0-20181122101859-297441e03548/go.mod h1:e6NPNENfs9mPDVNRekM7lKScauxd5kXTr1Mfyig6TDM=
@@ -190,8 +192,6 @@ github.com/pingcap/kvproto v0.0.0-20191202044712-32be31591b03/go.mod h1:WWLmULLO
 github.com/pingcap/log v0.0.0-20190715063458-479153f07ebd/go.mod h1:WpHUKhNZ18v116SvGrmjkA9CBhYmuUTKL+p8JC9ANEw=
 github.com/pingcap/log v0.0.0-20191012051959-b742a5d432e9 h1:AJD9pZYm72vMgPcQDww9rkZ1DnWfl0pXV3BOWlkYIjA=
 github.com/pingcap/log v0.0.0-20191012051959-b742a5d432e9/go.mod h1:4rbK1p9ILyIfb6hU7OG2CiWSqMXnp3JMbiaVJ6mvoY8=
-github.com/pingcap/parser v0.0.0-20191210060830-bdf23a7ade01 h1:q1rGnV/296//bArDP7cDWWaSrhaeEKZY+gIo+Jb0Gyk=
-github.com/pingcap/parser v0.0.0-20191210060830-bdf23a7ade01/go.mod h1:1FNvfp9+J0wvc4kl8eGNh7Rqrxveg15jJoWo/a0uHwA=
 github.com/pingcap/pd v1.1.0-beta.0.20191210055626-676ddd3fbd2d h1:0uUwCayeh1U4r1n7kb4gHf2ZbiI9fuVtXPCEpb2piBY=
 github.com/pingcap/pd v1.1.0-beta.0.20191210055626-676ddd3fbd2d/go.mod h1:Z/VMtXHpkOP+MnYnk4TL5VHc3ZwO1qHwc89zDuf5n8Q=
 github.com/pingcap/sysutil v0.0.0-20191126040022-986c5b3ed9a3 h1:HCNif3lukL83gNC2EBAoh2Qbz36+2p0bm0LjgnNfl1s=