insert into test ( id, name, password )
values
( 1, "test", "test" )
on duplicate key update name = "test",
password = "test"
replace into test ( id, name, password )
values
( 1, "test", "test" )
insert into和replace into的效能近乎相同，詳情可見此部落格。相比而言，insert into ... on duplicate key update ...的效能較為低下。
select
count( * ) as con,
date_format( createtime, '%y年%m月' ) as month
from
test
where
1 = 1
group by
date_format( createtime, '%y-%m' )
from_unixtime()方法
select
count( * ) as con,
date_format( from_unixtime( createtime ), '%y年%m月' ) as month
from
test
where
id = 1
group by
date_format( from_unixtime( createtime ), '%y-%m' )
unix_timestamp()方法將時間日期轉換成unix時間戳
unix_timestamp("2019-03-05 12:00:00");select
id,name,
password,
( case when id = 1 then '管理員' else '普通使用者' end ) as user_type,
( case when id % 2 = 0 then '女性使用者' else '男性使用者' end ) as user_***
where
1 =1
select
id,name,
password,
***,
( case *** when 1 then '男' when 2 then '女' else '未知' end )
where
1 =1
待定…
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