MySQL SQL Select 查询替换值

Question

I have this SQL Query, where i have a few case statements and count in order to pivot my "clase x" rows and it returns something like this.

| Nombre Completo | Clase 1 | Clase 2|
--------------------------------------
| Example name   |   3      |    5   |
--------------------------------------

And what I need, its to replace the number, if the number its > 0 then replace it with a yes, else replace it with NO. How can I do that? Mysql Query:

SELECT  DISTINCT concat_ws(' ',U.firstname, U.lastname) as  Nombre_Completo,
COUNT(CASE WHEN b.name="Clase 1" THEN b.name END) Clase1,
COUNT(CASE WHEN b.name="Clase 2" THEN b.name END) Clase2,
COUNT(CASE WHEN b.name="Clase 3" THEN b.name END) Clase3,
COUNT(CASE WHEN b.name="Clase 4" THEN b.name END) Clase4,
COUNT(CASE WHEN b.name="Clase 5" THEN b.name END) Clase5,
COUNT(CASE WHEN b.name="Clase 6" THEN b.name END) Clase6,
COUNT(CASE WHEN b.name="Clase 7" THEN b.name END) Clase7,
COUNT(CASE WHEN b.name="Clase 8" THEN b.name END) Clase8,
COUNT(CASE WHEN b.name="Clase 9" THEN b.name END) Clase9,
COUNT(CASE WHEN b.name="Clase 10" THEN b.name END) Clase10,
COUNT(CASE WHEN b.name="Clase 11" THEN b.name END) Clase11,
COUNT(CASE WHEN b.name="Clase 12" THEN b.name END) Clase12
FROM mdl_logstore_standard_log as L
LEFT JOIN mdl_course as C ON L.courseid = C.id 
left JOIN mdl_user as U on L.userid = U.ID
JOIN mdl_bigbluebuttonbn AS b ON L.objectid = b.id
JOIN mdl_role_assignments AS ra ON L.userid = ra.userid
JOIN mdl_role AS r ON r.id = ra.roleid
WHERE (C.shortname LIKE '%CSG012020%') AND (ra.roleid=5)  AND (ra.roleid NOT IN (3,4))
GROUP BY Nombre_Completo;

Answer 1

Use IF() to test the result of COUNT()

SELECT  DISTINCT concat_ws(' ',U.firstname, U.lastname) as  Nombre_Completo,
IF(COUNT(CASE WHEN b.name="Clase 1" THEN b.name END) > 0, 'Yes', 'No') Clase1,
IF(COUNT(CASE WHEN b.name="Clase 2" THEN b.name END) > 0, 'Yes', 'No') Clase2,
IF(COUNT(CASE WHEN b.name="Clase 3" THEN b.name END) > 0, 'Yes', 'No') Clase3,
IF(COUNT(CASE WHEN b.name="Clase 4" THEN b.name END) > 0, 'Yes', 'No') Clase4,
IF(COUNT(CASE WHEN b.name="Clase 5" THEN b.name END) > 0, 'Yes', 'No') Clase5,
IF(COUNT(CASE WHEN b.name="Clase 6" THEN b.name END) > 0, 'Yes', 'No') Clase6,
IF(COUNT(CASE WHEN b.name="Clase 7" THEN b.name END) > 0, 'Yes', 'No') Clase7,
IF(COUNT(CASE WHEN b.name="Clase 8" THEN b.name END) > 0, 'Yes', 'No') Clase8,
IF(COUNT(CASE WHEN b.name="Clase 9" THEN b.name END) > 0, 'Yes', 'No') Clase9,
IF(COUNT(CASE WHEN b.name="Clase 10" THEN b.name END) > 0, 'Yes', 'No') Clase10,
IF(COUNT(CASE WHEN b.name="Clase 11" THEN b.name END) > 0, 'Yes', 'No') Clase11,
IF(COUNT(CASE WHEN b.name="Clase 12" THEN b.name END) > 0, 'Yes', 'No') Clase12
FROM mdl_logstore_standard_log as L
LEFT JOIN mdl_course as C ON L.courseid = C.id 
left JOIN mdl_user as U on L.userid = U.ID
JOIN mdl_bigbluebuttonbn AS b ON L.objectid = b.id
JOIN mdl_role_assignments AS ra ON L.userid = ra.userid
JOIN mdl_role AS r ON r.id = ra.roleid
WHERE (C.shortname LIKE '%CSG012020%') AND (ra.roleid=5)  AND (ra.roleid NOT IN (3,4))
GROUP BY Nombre_Completo;

Answer 2

Every:

COUNT(CASE WHEN b.name="Clase X" THEN b.name END)

in your code can be written as:

SUM(b.name='Clase X')

because MySql evaluates boolean expressions like b.name='Clase 1' as 1 (true) or 0 (false).

Also, any integer value can be interpreted as false if it is 0 or true if it is different than 0 .

So you can write your query like this:

SELECT concat_ws(' ', U.firstname, U.lastname) Nombre_Completo,
       CASE WHEN SUM(b.name='Clase 1') THEN 'yes' ELSE 'no' END Clase1,
       CASE WHEN SUM(b.name='Clase 2') THEN 'yes' ELSE 'no' END Clase2,
       CASE WHEN SUM(b.name='Clase 3') THEN 'yes' ELSE 'no' END Clase3,
       CASE WHEN SUM(b.name='Clase 4') THEN 'yes' ELSE 'no' END Clase4,
       CASE WHEN SUM(b.name='Clase 5') THEN 'yes' ELSE 'no' END Clase5,
       CASE WHEN SUM(b.name='Clase 6') THEN 'yes' ELSE 'no' END Clase6,
       CASE WHEN SUM(b.name='Clase 7') THEN 'yes' ELSE 'no' END Clase7,
       CASE WHEN SUM(b.name='Clase 8') THEN 'yes' ELSE 'no' END Clase8,
       CASE WHEN SUM(b.name='Clase 9') THEN 'yes' ELSE 'no' END Clase9,
       CASE WHEN SUM(b.name='Clase 10') THEN 'yes' ELSE 'no' END Clase10,
       CASE WHEN SUM(b.name='Clase 11') THEN 'yes' ELSE 'no' END Clase11,
       CASE WHEN SUM(b.name='Clase 12') THEN 'yes' ELSE 'no' END Clase12
FROM mdl_logstore_standard_log as L
LEFT JOIN mdl_course as C ON L.courseid = C.id 
left JOIN mdl_user as U on L.userid = U.ID
JOIN mdl_bigbluebuttonbn AS b ON L.objectid = b.id
JOIN mdl_role_assignments AS ra ON L.userid = ra.userid
JOIN mdl_role AS r ON r.id = ra.roleid
WHERE (C.shortname LIKE '%CSG012020%') AND (ra.roleid=5)  AND (ra.roleid NOT IN (3,4))
GROUP BY Nombre_Completo;

I removed DISTINCT because it is not needed since you GROUP BY Nombre_Completo .