diff --git a/chain.go b/chain.go
index 4ede69b..1b7c415 100644
--- a/chain.go
+++ b/chain.go
@@ -728,11 +728,13 @@ func (this *Query) UpdateAllStmt() error {
 		select_sql := `SELECT
 						 ` + strings.Join(title_field, " , ") + `
 					FROM DUAL`
-
-		if len(valSql) > 1 {
-			for i := 0; i < len(valSql)-1; i++ {
-				select_sql += ` UNION ALL ` + select_sql
+		select_res := ""
+		for i := 0; i < len(valSql); i++ {
+			if i > 0 {
+				select_res += ` UNION ALL `
 			}
+
+			select_res += select_sql
 		}
 		//和mysql更新或添加机制不一样，需指定on条件
 		on_field := `t.id = s.id`
@@ -747,7 +749,7 @@ func (this *Query) UpdateAllStmt() error {
 		}
 
 		sql = `MERGE INTO ` + dbName + ` AS t
-				USING (` + select_sql + `
+				USING (` + select_res + `
 				) s
 				ON (` + on_field + `)
 				WHEN MATCHED THEN
diff --git a/transaction_chain.go b/transaction_chain.go
index 26f995d..f4b0ff4 100644
--- a/transaction_chain.go
+++ b/transaction_chain.go
@@ -685,10 +685,13 @@ func (this *TxQuery) UpdateAllStmt() error {
 						 ` + strings.Join(title_field, " , ") + `
 					FROM DUAL`
 
-		if len(valSql) > 1 {
-			for i := 0; i < len(valSql)-1; i++ {
-				select_sql += ` UNION ALL ` + select_sql
+		select_res := ""
+		for i := 0; i < len(valSql); i++ {
+			if i > 0 {
+				select_res += ` UNION ALL `
 			}
+
+			select_res += select_sql
 		}
 		//和mysql更新或添加机制不一样，需指定on条件
 		on_field := `t.id = s.id`
@@ -703,7 +706,7 @@ func (this *TxQuery) UpdateAllStmt() error {
 		}
 
 		sql = `MERGE INTO ` + dbName + ` AS t
-				USING (` + select_sql + `
+				USING (` + select_res + `
 				) s
 				ON (` + on_field + `)
 				WHEN MATCHED THEN