sql查詢用於過濾數據，其中表的同一列上有多個條件

Question

我有以下示例表。 具有名稱和鍵列唯一記錄的組合的表

ID   name      key          key_type 
-----------------------------------
118  ab         12          aw1 
119  fb         13          1Y2 
120  cb         14          qw3 
121  ab         15          4123
122  cs         12          23d2

select * from Sample where name ='ab' and key= '12' 

select * from Sample where name ='fb' and key= '13' 

如何為兩個記錄編寫單個查詢？

Answer 1

最簡單的方法是union all合並

select * from Sample where name ='ab' and key= '12' 
union all
select * from Sample where name ='fb' and key= '13' 

Answer 2

最簡單的方法是

select * 
  from Sample 
  where (name = 'ab' and `key` = '12') 
    or (name = 'fb' and `key` = '13')

演示在這里： http : //sqlfiddle.com/#!9/3eabc/3

在（name， key ）上添加一個索引以達到良好的效果。

create index name_key on sample(name, `key`);