在单个查询中添加多个 where 子句

Question

I want to run an SQL query from the Node.js. I want to show the total number of projects that have specific status in each of the 4 quarters.

Here's my code for the 2 quarters:

SELECT
SUM(CurrentStatus = 'On Hold') onHold_Q1,
SUM(CurrentStatus = 'In Progress') inProgress_Q1,
SUM(CurrentStatus = 'Not Started') notStarted_Q1,
SUM(CurrentStatus = 'Completed') completed_Q1,
SUM(CurrentStatus = 'Routine Activity') routineActivity_Q1,
SUM(CurrentStatus = 'Done But Not Published') doneButNotPublished_Q1
FROM office.officedata
WHERE Quarter = 'Q1';

SELECT
SUM(CurrentStatus = 'On Hold') onHold_Q2,
SUM(CurrentStatus = 'In Progress') inProgress_Q2,
SUM(CurrentStatus = 'Not Started') notStarted_Q2,
SUM(CurrentStatus = 'Completed') completed_Q2,
SUM(CurrentStatus = 'Routine Activity') routineActivity_Q2,
SUM(CurrentStatus = 'Done But Not Published') doneButNotPublished_Q2
FROM office.officedata
WHERE Quarter = 'Q2'; 

I want to join the above two queries into a single query. Since, I am going to run this query from the backend (Node.js), I want the data for the quarters all at once in a single request. I don't want to send multiple request to mySQL. How can I do that?

Answer 1

You can group by quarter:

SELECT Quarter,
    SUM(CurrentStatus = 'On Hold') onHold,
    SUM(CurrentStatus = 'In Progress') inProgress,
    SUM(CurrentStatus = 'Not Started') notStarted,
    SUM(CurrentStatus = 'Completed') completed,
    SUM(CurrentStatus = 'Routine Activity') routineActivity,
    SUM(CurrentStatus = 'Done But Not Published') doneButNotPublished
FROM office.officedata
WHERE Quarter in ('Q1', 'Q2')
GROUP BY Quarter;

This generates one row per quarter, with the values in columns. While it would be possible to put everything on the same row (with more typing,). I find that this result is more useful.

Answer 2

You want to use the UNION clause

SELECT
SUM(CurrentStatus = 'On Hold') onHold,
SUM(CurrentStatus = 'In Progress') inProgress,
SUM(CurrentStatus = 'Not Started') notStarted,
SUM(CurrentStatus = 'Completed') completed,
SUM(CurrentStatus = 'Routine Activity') routineActivity,
SUM(CurrentStatus = 'Done But Not Published') doneButNotPublished
FROM office.officedata
WHERE Quarter = 'Q1'
UNION SELECT
SUM(CurrentStatus = 'On Hold') onHold,
SUM(CurrentStatus = 'In Progress') inProgress,
SUM(CurrentStatus = 'Not Started') notStarted,
SUM(CurrentStatus = 'Completed') completed,
SUM(CurrentStatus = 'Routine Activity') routineActivity,
SUM(CurrentStatus = 'Done But Not Published') doneButNotPublished
FROM office.officedata
WHERE Quarter = 'Q2';