对于MySql，如果不为null，则无法仅使用简单的

我在我的店铺表中添加了一个名为“个人id”的字段。如果personal_id字段包含一个id，我想做的是获取上述信息。我将如何实现这一点？一些例子或提示将是伟大的！我很想听到你的消息

试试这个

如果您想加入my_shop3的个人id，请使用下面的

SELECT `a`.`id`   AS `id`, 
       `a`.`info` AS `info`, 
       `a`.`type` AS `type`, 
       `a`.`disp` AS `disp`, 
       `a`.`emp`  AS `emp`, 
       `a`.`tel`  AS `tel`, 
       `a`.`img`  AS `img`, 
       `a`.`job`  AS `job` 
FROM ((`my_shop` `a` 
       LEFT JOIN `my_shop2` `b` 
           ON(( `a`.`id` = `b`.`my_shop_id` ))) 
       JOIN `my_shop3` `c` 
           ON(( Ifnull(`b`.`my_shop_id`, `a`.`id`) = `c`.`id` ))) 

SELECT a.id AS id, 
       a.info AS info, 
       a.type AS type, 
       a.disp AS disp, 
       a.emp  AS emp, 
       a.tel  AS tel, 
       a.img  AS img, 
       a.job  AS job 
FROM my_shop a  LEFT JOIN my_shop2 b ON a.id = b.my_shop_id 
       JOIN my_shop3 c ON Ifnull(b.my_shop_id, a.id) = c.id  AND a.personal_id = C.id

如果您想在

WHERE

子句中使用personal_id，请使用下面的

SELECT `a`.`id`   AS `id`, 
       `a`.`info` AS `info`, 
       `a`.`type` AS `type`, 
       `a`.`disp` AS `disp`, 
       `a`.`emp`  AS `emp`, 
       `a`.`tel`  AS `tel`, 
       `a`.`img`  AS `img`, 
       `a`.`job`  AS `job` 
FROM ((`my_shop` `a` 
       LEFT JOIN `my_shop2` `b` 
           ON(( `a`.`id` = `b`.`my_shop_id` ))) 
       JOIN `my_shop3` `c` 
           ON(( Ifnull(`b`.`my_shop_id`, `a`.`id`) = `c`.`id` ))) 

SELECT a.id AS id, 
       a.info AS info, 
       a.type AS type, 
       a.disp AS disp, 
       a.emp  AS emp, 
       a.tel  AS tel, 
       a.img  AS img, 
       a.job  AS job 
FROM my_shop a  LEFT JOIN my_shop2 b ON a.id = b.my_shop_id 
       JOIN my_shop3 c ON Ifnull(b.my_shop_id, a.id) = c.id  AND a.personal_id = C.id

选择a.id作为id，
a、 信息作为信息，
a、 类型作为类型，
a、 disp作为disp，
a、 emp作为emp，
a、 电话作为电话，
a、 img作为img，
a、 以工代赈
从我的店铺a左边加入我的店铺2 b
在Ifnull上加入my_shop3 c（b.my_shop_id，a.id）=c.id
其中a.personal_id=

请使用下面提到的代码来解决您的问题

SELECT a.id AS id, 
       a.info AS info, 
       a.type AS type, 
       a.disp AS disp, 
       a.emp  AS emp, 
       a.tel  AS tel, 
       a.img  AS img, 
       a.job  AS job 
FROM my_shop a  LEFT JOIN my_shop2 b ON a.id = b.my_shop_id 
       JOIN my_shop3 c ON Ifnull(b.my_shop_id, a.id) = c.id  
WHERE a.personal_id = <id value>

若要将

个人_id

与特定的表列值进行比较，请使用下面的where命令

SELECT 
    a.id   AS id, 
    a.info AS info, 
    a.type AS type, 
    a.disp AS disp, 
    a.emp  AS emp, 
    a.tel  AS tel, 
    a.img  AS img, 
    a.job  AS job 
FROM my_shop a 
LEFT JOIN my_shop2 b ON a.id = b.my_shop_id 
INNER JOIN my_shop3 c ON Ifnull(b.my_shop_id, a.id) = c.id
WHERE a.personal_id IS NOT NULL;

其中a.personal\u id=

---

请尝试此操作并让我们知道。

您有没有收到任何错误？

个人id

字段在您的查询中不会出现。请添加示例数据和预期结果。问题是我不知道如何将“personal_id”条件添加到当前查询的以下代码中，因为我完全是初学者。添加where条件如下选择

a

id

AS

id

，

a

info

AS

info

，

a
a
type
AS
type
，
a
disp
AS
disp
，
a
emp
AS
emp
，
a
tel
AS
tel
，
a
img
AS
img
，
a
b
on（
a
b
我的店铺id
）加入
我的店铺3
c
on（
b
我的店铺id
=
c
id
），其中
a
个人id
=X