PHP/MYSQL：左连接没有得到正确的父级详细信息

Question

SELECT smirt.id as mid,
pc.packet_name as pname, 
pcs.packet_name as mainn, 
smirt.p_status as st , 
smirt.new_value as weight , 
smirt.packet_id, 
smirt.parent_packet_id 
FROM issue_receive_process AS smirt 
LEFT JOIN packet_creation AS pc ON  pc.id = smirt.packet_id
LEFT JOIN packet_creation AS pcs ON pcs.id = pc.parent_packet_id 
WHERE smirt.type = 53
AND smirt.main_kapan_id IN(1,2) 
ORDER BY smirt.packet_id

从上面的查询我得到以下详细信息：

但是上面是错误的

因为 pname 是我的子包 mainn 是我的主数据包

实际上我需要（应该是）pname（NULL，0004）和mainn（0003,0002）如下（下图是编辑图像）：

因为 0003 , 0002 是主包， 0004 是 0002 的子包 ... 0003 没有任何子包 ....

如果我错了，有什么可以帮助我的。

谢谢

更新：父表图像（issue_receive_process AS smirt）

根据用户：KISHORE BELOW QUERY：

SELECT smirt.id
,smirt.packet_id
,smirt.main_kapan_id
,pc.id
,pc.packet_name
,pc.parent_packet_id 
FROM issue_receive_process AS smirt 
LEFT JOIN packet_creation AS pc ON  pc.id = smirt.packet_id
WHERE pc.packet_name IN ('0002','0003','0004') 
ORDER BY smirt.packet_id

结果如下：

第二次更新表： packet_creation 下面的详细信息按照以下查询

SELECT *
FROM `packet_creation`
WHERE `id`
IN ( 5, 11, 9 )
LIMIT 0 , 30

Answer 1

我对你想要什么感到很困惑。

当您使用测试数据运行时，您拥有的 SQL 将给出您描述为错误的数据。它正在获取一条记录和与之配套的数据包，然后是该数据包的父级。如果数据包没有父数据包，则（并且应该）返回 NULL。

我认为您唯一想要的是，如果没有父记录，那么您希望子数据包 id 作为父数据包 id 返回，而子数据包 id 返回为 NULL。

如果是这样的话：-

SELECT smirt.id as mid,
        IF(pcs.packet_name IS NULL, NULL, pc.packet_name) as pname, 
        IF(pcs.packet_name IS NULL, pc.packet_name, pcs.packet_name) as mainn, 
        smirt.p_status as st , 
        smirt.new_value as weight , 
        smirt.packet_id, 
        smirt.parent_packet_id 
FROM issue_receive_process AS smirt 
LEFT JOIN packet_creation AS pc ON  pc.id = smirt.packet_id
LEFT JOIN packet_creation AS pcs ON pcs.id = pc.parent_packet_id 
WHERE smirt.type = 53
AND smirt.main_kapan_id IN(1,2) 
ORDER BY smirt.packet_id

根据上述查询结果如下：

因此我得到的最终输出是 3,4,2 但应该是 0003,0002,0004

编辑 - 将字段转换为 char 以尝试强制前导零：-

SELECT smirt.id as mid,
        IF(pcs.packet_name IS NULL, NULL, CAST(pc.packet_name AS CHAR)) as pname, 
        IF(pcs.packet_name IS NULL, CAST(pc.packet_name AS CHAR), CAST(pcs.packet_name AS CHAR)) as mainn, 
        smirt.p_status as st , 
        smirt.new_value as weight , 
        smirt.packet_id, 
        smirt.parent_packet_id 
FROM issue_receive_process AS smirt 
LEFT JOIN packet_creation AS pc ON  pc.id = smirt.packet_id
LEFT JOIN packet_creation AS pcs ON pcs.id = pc.parent_packet_id 
WHERE smirt.type = 53
AND smirt.main_kapan_id IN(1,2) 
ORDER BY smirt.packet_id