将多个sql语句合并到列中

Question

I'm pretty new to SQL and I'm running something like this to pull out some data. But Currently I am running them one statement at a time and copying them to excel. Is there a way to run all these together? Level would be the same for each statement, but count(ID) will be different. There might also be some days where a level does not have any data.

select 
    count(ID), level 
from table1 
where createat >= "2013-11-22 00:00:00" and createat <= "2013-11-22 23:59:59" 
group by level;

select 
    count(ID), level 
from table1 
where createat >="2013-11-23 00:00:00" and createat <= "2013-11-23 23:59:59" 
group by level;

select 
    count(ID), level 
from table1 
where createat >= "2013-11-24 00:00:00" and createat <= "2013-11-24 23:59:59" 
group by level;

Thanks for the help! I'm hoping to learn more about how to write these.

Answer 1

SELECT
  level,
  COUNT(CASE WHEN createat>='2013-11-22' and createat<'2013-11-23' THEN id ELSE NULL END)   AS day_1_count,
  COUNT(CASE WHEN createat>='2013-11-23' and createat<'2013-11-24' THEN id ELSE NULL END)   AS day_2_count,
  COUNT(CASE WHEN createat>='2013-11-24' and createat<'2013-11-25' THEN id ELSE NULL END)   AS day_3_count
FROM
  table1
GROUP BY
  level
WHERE
  createat>='2013-11-22' and createat<'2013-11-25'

Although, it would probably make more sense to join on a table with the dates that you need, rather than hard code them.

Also, note that SQL works on a fixed number of columns, this does not work if you want one query for 3 days and then to reuse it for 5 days. For that you need to keep it as one result per Row.

Answer 2

Try this:

SELECT t.level, SUM(CASE WHEN DATE(createat) = '2013-11-22' THEN 1 ELSE 0 END) AS day1,
       SUM(CASE WHEN DATE(createat) = '2013-11-23' THEN 1 ELSE 0 END) AS day2,
       SUM(CASE WHEN DATE(createat) = '2013-11-24' THEN 1 ELSE 0 END) AS day3
FROM table1 t
WHERE DATE(t.createat) >= "2013-11-22" AND DATE(t.createat) <= "2013-11-24" 
GROUP BY t.level;

OR

SELECT t.level, SUM(CASE WHEN t.createat >= "2013-11-22 00:00:00" AND t.createat <= "2013-11-22 23:59:59" THEN 1 ELSE 0 END) AS day1,
       SUM(CASE WHEN t.createat >= "2013-11-23 00:00:00" AND t.createat <= "2013-11-23 23:59:59" THEN 1 ELSE 0 END) AS day2,
       SUM(CASE WHEN t.createat >= "2013-11-24 00:00:00" AND t.createat <= "2013-11-24 23:59:59" THEN 1 ELSE 0 END) AS day3
FROM table1 t
WHERE t.createat >= "2013-11-22 00:00:00" AND t.createat <= "2013-11-24 23:59:59" 
GROUP BY t.level;

Answer 3

The simple edit to the query you posted is:

select count(ID), level 
from table1 
where createat >= "2013-11-22 00:00:00" and createat <= "2013-11-22 23:59:59" 
group by level
union
select count(ID), level 
from table1 
where createat >="2013-11-23 00:00:00" and createat <= "2013-11-23 23:59:59" 
group by level
union
select count(ID), level 
from table1 
where createat >= "2013-11-24 00:00:00" and createat <= "2013-11-24 23:59:59" 
group by level

However if you are trying to get the count, level value and date for each day then you could use a query like this:

SELECT COUNT(*), level, CAST(createat AS DATE)
FROM table1
GROUP BY level, CAST(createat AS DATE)