MySQL更改标签值选择不同并计数

Question

I have the following query:

SELECT DISTINCT GRAD_ACAD,
COUNT(GRAD_ACAD) AS subtotal
FROM academicos
WHERE CCN REGEXP 'I|D65'
GROUP BY GRAD_ACAD
ORDER BY GRAD_ACAD

which results are:

GRAD_ACAD  subtotal
DOC          11
LIC           2
MTR           3

What i want to do is to change the values labels into the following:

GRAD_ACAD      subtotal
Doctorado        11
Licenciatura      2
Maestría          3

I have tried Case when like this but i can't get it to work:

SELECT DISTINCT GRAD_ACAD CASE GRAD_ACAD WHEN 'DOC' THEN 'doctorado' ELSE(SELECT GRAD_ACAD) END AS GRAD_ACAD,
COUNT(GRAD_ACAD) AS subtotal
FROM academicos
WHERE CCN REGEXP 'I|D65'
GROUP BY GRAD_ACAD
ORDER BY GRAD_ACAD

How can i fix this?

Answer 1

case GRAD_ACAD when 'DOC' then 'Doctorado' when 'LIC' then 'Licenciatura' when 'MTR' then 'Maestria' else GRAD_ACAD end

您需要在SELECT和GROUP BY中都放入相同的子句

Answer 2

No need to use DISTINCT here

SELECT  CASE GRAD_ACAD WHEN 'DOC' THEN 'doctorado' 
                 WHEN 'LIC' then 'Licenciatura'
                 WHEN 'MTR' then 'Maestria'
                 ELSE GRAD_ACAD end,
COUNT(GRAD_ACAD) AS subtotal
FROM academicos
WHERE CCN REGEXP 'I|D65'
GROUP BY 1
ORDER BY 1;

Notice that I used group by 1 and order by 1 which specify the first selected field, instead of repeating the case in both clause.