條件語句case
case
when a.business_mark!='' then 2endas source_type,
條件語句 case else
case
when a.business_mark!='' then 2when a.rebate_id!='' then 1else0endas source_type,
case a.is_pay
when1 then 20when2 then 10endas recharge_state,
if語句
if(a.receive_time='',null,from_unixtime(a.receive_time)) as time_receive_user_pay,
如果receive_time為空，則取第二個值，否則就去第三個值
時間轉化 (1477984283 轉 y-m-d h:i:s)
from_unixtime(a.add_time) as time_publish_user_pay,
字段長度擷取 cast(a.price*0.93 as decimal(18,2))
case
when a.rebate_id!=' ' or a.business_mark !=' ' then cast(a.price*0.85 as decimal(18,2)) *100else cast(a.price*0.93 as decimal(18,2)) *100endas actual_pay_to_receiver_amount,
子查詢casewhen a.business_mark!='' then (select id from dl_business where mark=a.business_mark)
when a.rebate_id!=''then a.rebate_id
endas source_id,
條件為空查詢
select * from `dl_order` where business_mark is not null;
select* from `dl_order` where business_mark !='';
select * from `dl_order` where business_mark is null;
select max(length(desc)) from table order by length desc
兩表查詢
selecta.member_idasuser_id,
a.game_levelasdivision_id,
a.add_timeastime_create,
b.nameasdivision_namefromdl_member_attest a
left join dl_game_type b on a.game_level=b.id
limit0,10
三表查詢
select
a.idasuser_id,
c.idasdivision_id,
c.nameasdivision_name,
a.member_markashadchetman_sn,
case
when b.is_status= 1 then 0when b.is_status= 2 then 20when b.is_status= 3 then 10end
as hadchetman_state,
b.add_timeastime_createfromdl_member a
left join dl_member_attest b on a.id=b.member_id
inner join dl_game_type c on b.game_level=c.id
limit0,10
多個left join
selectif(a.pay_status =1,null,from_unixtime(a.add_time)) astime_publish_user_pay,if(a.receive_time='',null,from_unixtime(a.receive_time)) astime_receive_user_pay,
game_area.nameasgame_area_name,
last_division.nameaslast_season_division_name,
current_division.nameascurrent_division_name,
target_division.nameastarget_division_name,
member.mobileasreceive_user_name,0 asis_delete,1 asdata_versionfromdl_order a
left join dl_order_lol b on b.order_id=a.id
left join dl_game_type game_area on b.game_area=game_area.id
left join dl_game_type last_division on b.game_start_level=last_division.id
left join dl_game_type current_division on b.game_start_level=current_division.id
left join dl_game_type target_division on b.game_start_level=target_division.id
left join dl_member member on a.receive_member_id=member.id
order by a.id desc
limit0,100
mysql轉移老資料 mysql匯入匯出資料
window下 1.匯出整個資料庫 mysqldump u 使用者名稱 p 資料庫名 匯出的檔名 mysqldump u dbuser p dbname dbname.sql 2.匯出乙個表 mysqldump u 使用者名稱 p 資料庫名 表名 匯出的檔名 mysqldump u dbuser p...
mysql 字段 MySQL欄位型別詳解
mysql支援大量的列型別，它可以被分為3類 數字型別 日期和時間型別以及字串 字元 型別。本節首先給出可用型別的乙個概述，並且總結每個列型別的儲存需求，然後提供每個類中的型別性質的更詳細的描述。概述有意簡化，更詳細的說明應該考慮到有關特定列型別的附加資訊，例如你能為其指定值的允許格式。由mysql...
mysql表示字段 MySQL欄位型別
1 字段型別 字段型別分別為 數值型別 字串型別 日期時間型別。1.1 數值型別 數值型別分為整數型別和小數型別。整數型別為tinyint smallint mediumint int bigint。小數型別分為浮點型和定點型，有float double decimal。1.1.1 tinyint ...