Question

我有两张表如下：

Suppliers: supplier_id, supplier_pw 123456 zzzzz 647890 yyyyy

Customers: customer_id, customer_pw 00000 zzzzz 11111 yyyyy

我已将两个表的ID设置为唯一键和主键。运行以下查询后：

$ username = 123456，$ password = zzzzzz。

SELECT * FROM suppliers, customers WHERE (suppliers.supplier_id = '$username' AND suppliers.supplier_pw = '$password') OR (customers.customer_id = '$username' AND customers.customer_pw = '$password'

它返回来自供应商的结果，其中id = 123456也是来自客户的密码= zzzzzz的结果。但我想让它只返回匹配id和密码的那个。我应该在哪里更改查询？

更新表格结构：

供应商：

supplier_id（PK，unique），supplier_pw，supplier_lastname，supplier_firstname，supplier_email（unique），supplier_phone，company_name（unique），company_address，company_city，company_state，company_zip

客户：

customer_id（PK，unique），customer_pw，customer_lastname，customer_firstname，customer_email（unique），customer_phone，customer_address，customer_city，cusomter_state，customer_zip

Answer 1

如果要选择与用户名和密码输入匹配的数据，如果匹配，则需要来自两个表，然后您可以使用union all作为

select 
supplier_id as id,
supplier_lastname as lastname,
supplier_firstname as firstname,
supplier_email as email ,
supplier_phone as phone,
'Supplier' as entity_name
from suppliers 
where suppliers.supplier_id = '$username' AND suppliers.supplier_pw = '$password'
union all
select
customer_id as id,
customer_lastname as lastname,
customer_firstname as firstname,
customer_email as email,
customer_phone as phone,
'Customer' as entity_name 
customers.customer_id = '$username' AND customers.customer_pw = '$password'

请注意，我从两个表中选择了几个列，并添加了可以添加更多内容的别名，但是请确保两个查询具有相同的选择数，然后添加一个名为entity_name的额外列来告诉您如果你有来自两个表的匹配数据，那么该行的表格就会出现。

检查两个不同的表中的用户名时，只返回一个用户

1 个答案: