在没有任何主键的情况下联接两个表，两个表都具有外键
[英]Joining of two tables without any primary key both tables have foreign key
问题描述
I have three tables : 
我有三个表：
List(lid,list_name) 清单（lid，list_name）
Phone(pid,lid,phno) 电话（pid，lid，phno）
Emails(eid,lid,email) 电子邮件（eid，lid，email）
Tables having records as shown here 具有记录的表如下所示
List 清单
lid ----------- list_name
**1** ------------- **ads**
**2** ------------- **visits**
Phone 电话
pid ------- lid ----------- phno
10 ---------**1** ---------- 9988123456
20 ---------**1** ---------- 9988123454
30 ---------**2** ---------- 9988222222
40 ---------**2** ---------- 9988333333
Emails 电邮
eid ------- lid ----------- email
1 ---------**1** ---------- xyz@abc.com
2 ---------**1** ---------- abc@abc.com
3 ---------**2** ---------- list2@abc.com
4 ---------**2** ---------- list21@abc.com
I want to create join between Table Emails and Phone with foreign key lid. 我想在带有外键盖的表电子邮件和电话之间创建联接。
I tried it like this 我这样尝试过
SELECT * FROM phone left join emails on phone.lid = emails.lid WHERE 1
and got output form this query 并从此查询输出
pid -- lid ---- phno ---------- eid --- lid --- email
10 ----- 1 --- 9988123456 -- **1** --- 1 --- xyz@abc.com
20 ----- 1 --- 9988123454 ---**1** --- 1 --- xyz@abc.com
10 ----- 1 --- 9988123456 ---**2** --- 1 --- abc@abc.com
20 ----- 1 --- 9988123454 ---**2** --- 1 --- abc@abc.com
30 ----- 2 --- 9988222222 -- **3** --- 2 --- list2@abc.com
40 ----- 2 --- 9988333333 ---**3** --- 2 --- list2@abc.com
30 ----- 2 --- 9988222222 ---**4** --- 2 --- list21@abc.com
40 ----- 2 --- 9988333333 ---**4** --- 2 --- list21@abc.com
Here you can see we are getting duplicate emails and duplicate phone number, but I want the result that there should not be any duplicate email and duplicate phone in any row they both must be unique as shown below: 在这里您可以看到我们收到重复的电子邮件和重复的电话号码，但是我希望结果是在任何行中都不应有重复的电子邮件和重复电话，它们都必须是唯一的，如下所示：
pid -- lid ---- phno ---------- eid --- lid --- email
20 ----- 1 --- 9988123454 ---**1** --- 1 --- xyz@abc.com
10 ----- 1 --- 9988123456 ---**2** --- 1 --- abc@abc.com
30 ----- 2 --- 9988222222 -- **3** --- 2 --- list2@abc.com
40 ----- 2 --- 9988333333 ---**4** --- 2 --- list21@abc.com
I'm stuck here. 我被困在这里。 Please suggest me the solution. 请给我建议解决方案。
1 个解决方案
解决方案1
0 2014-05-21 14:24:55
Your table structure would not allow you to get the output you expect. 您的表结构不允许您获得期望的输出。 In table Phone (according to given data) lid cannot be a candidate key. 在表Phone（根据给定数据）中， 盖不能用作候选键。 Same goes to lid in table Emails. 表电子邮件的盖子也是如此。
lid cannot be used as a foreign key. 盖子不能用作外键。 A foreign key must reference either the primary key or a unique key(candidate key) of the parent table. 外键必须引用父表的主键或唯一键（候选键）。 But this is not the case in either tables. 但这两个表都不是这种情况。
I would suggest introducing a new column to get the one-to-one mapping you need 我建议引入一个新列，以获取您所需的一对一映射
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