ddl: fix alter column set default wrongly updates the schema (#32249)

close #31074
pingcap · Feb 11, 2022 · 6d2ad99 · 6d2ad99
1 parent c0244a3
commit 6d2ad99
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/ddl/ddl_api.go b/ddl/ddl_api.go
@@ -4643,10 +4643,11 @@ func (d *ddl) AlterColumn(ctx sessionctx.Context, ident ast.Ident, spec *ast.Alt
 
 	colName := specNewColumn.Name.Name
 	// Check whether alter column has existed.
-	col := table.FindCol(t.Cols(), colName.L)
-	if col == nil {
+	oldCol := table.FindCol(t.Cols(), colName.L)
+	if oldCol == nil {
 		return ErrBadField.GenWithStackByArgs(colName, ident.Name)
 	}
+	col := table.ToColumn(oldCol.Clone())
 
 	// Clean the NoDefaultValueFlag value.
 	col.Flag &= ^mysql.NoDefaultValueFlag