我想要隱藏我的select查詢中的某一列,並發現跳過列名可以做到這一點,但是對於這種情況,正確的語法是什麼?如何在mysql中的select查詢中使用跳過列名
這裏是我的代碼
select t1.location, MAX(DATE_ADD((FROM_UNIXTIME(t2.t_stamp/1000)),INTERVAL 4 HOUR) AS Tstamp,
max(case when t2.locationid = '2847' then t2.value end) MR,
max(case when t2.locationid = '2839' then t2.value end) Flow,
max(case when t2.locationid = '2834' then t2.value end) Pressure,
max(case when t2.locationid = '2836' then t2.value end) Level
from table2 t2
inner join table1 t1
on t1.id = '2847'
group by t1.location
等輸出我有最新的值列,
Location | Tstamp | MR | Flow | Pressure | Level
East | 2013-11-10 12:00 PM | 10 | 20 | 30 | 40
四小時了
Location | Tstamp | MR | Flow | Pressure | Level
East | 2013-11-10 08:00 AM | 20 | 25 | 34 | 45
,我想發生什麼是因爲它只是:
Location | MR | Flow | Pressure | Level
East | 20 | 25 | 34 | 45
如果我從select查詢中刪除了t_stamp,我怎麼能在4小時前顯示這些值?
你試過了什麼? –
如果你不想要該領域,爲什麼選擇它,尤其是當它迫使數據庫浪費時間做一堆日期數學只是將被扔掉 –
@viakondratiuk我試過這樣-MAX(DATE_ADD((FROM_UNIXTIME(t2.t_stamp/1000)),INTERVAL 4 HOUR)和--MAX(DATE_ADD((FROM_UNIXTIME(t2.t_stamp/1000)),INTERVAL 4 HOUR) – hearmeroar