add SelectBuilder methods ForUpdateNoWait and ForUpdateSkipLocked (#114)

Author: rck109d

builder.go

@@ -453,6 +453,16 @@ func (b *SelectBuilder) ForUpdate() *SelectBuilder {
 	return b
 }
 
+func (b *SelectBuilder) ForUpdateNoWait() *SelectBuilder {
+	b.Select.Lock = " FOR UPDATE NOWAIT"
+	return b
+}
+
+func (b *SelectBuilder) ForUpdateSkipLocked() *SelectBuilder {
+	b.Select.Lock = " FOR UPDATE SKIP LOCKED"
+	return b
+}
+
 // WithSharedLock sets the LOCK IN SHARE MODE tag on the statement
 // causing the result rows to be read locked (dependent on the
 // specific MySQL storage engine).

builder_test.go

@@ -491,6 +491,10 @@ func TestSelectBuilder(t *testing.T) {
 			"SELECT DISTINCT * FROM `users`"},
 		{users.Select("*").ForUpdate(),
 			"SELECT * FROM `users` FOR UPDATE"},
+		{users.Select("*").ForUpdateNoWait(),
+			"SELECT * FROM `users` FOR UPDATE NOWAIT"},
+		{users.Select("*").ForUpdateSkipLocked(),
+			"SELECT * FROM `users` FOR UPDATE SKIP LOCKED"},
 		{users.Select("*").WithSharedLock(),
 			"SELECT * FROM `users` LOCK IN SHARE MODE"},
 		{users.Select("*").Comments([]string{"quux", "quuz"}),