mysql - MySQL仅在条件为真时才插入

我有几个insert语句，我只想在它们为真时执行它们。
下面是我的例子：

START TRANSACTION;

INSERT INTO fields (field_name, control_type_id, needs_approval)
VALUES
('Array Photos', 3, 0);

INSERT INTO field_to_job_type (field_id, job_type_id, sequence_number, parent_id)
VALUES
(last_insert_id(), (SELECT job_type_id FROM job_types WHERE job_type_name = 'Cash'), 1, (SELECT field_id FROM fields where field_name = 'Photo Pack'));

COMMIT;

现在，我只想在这个查询只有一个结果时运行第二个查询：
SELECT job_type_id FROM job_types WHERE job_type_name = 'Cash'。
如果该查询返回2个结果，我将放弃该事务。
有可能吗？我试过的东西：

START TRANSACTION;
INSERT ...;
INSERT ...;
IF(SELECT count(job_type_name) FROM job_types WHERE job_type_name = 'Cash') = 1, 'COMMIT', 'ROLLBACK');

显然，这不起作用。

最佳答案

在变量中选择计数，然后在比较中使用它。

DECLARE total_row INT DEFAULT 0

START TRANSACTION;

INSERT INTO fields (field_name, control_type_id, needs_approval)
VALUES ('Array Photos', 3, 0);


SELECT count(job_type_name) FROM job_types WHERE job_type_name = 'Cash' INTO total_rows;

IF total_rows =2 THEN
    ROLLBACK;
ELSE

    INSERT INTO field_to_job_type (field_id, job_type_id, sequence_number, parent_id)
    VALUES (last_insert_id(), (SELECT job_type_id FROM job_types WHERE job_type_name = 'Cash'), 1, (SELECT field_id FROM fields where field_name = 'Photo Pack'));
   COMMIT;
END IF;