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

… (#32264) close #31074
pingcap · Feb 23, 2022 · 840c6a4 · 840c6a4
1 parent c65493d
commit 840c6a4
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/ddl/ddl_api.go b/ddl/ddl_api.go
@@ -4561,10 +4561,11 @@ 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