Select from another table based on condition - sql

Question

I am new to SQL Server and SQL queries. These are my three tables:
Primary keys
Table 1: CaseId
Table 2: ID
Table 3: parentId
In table 3 - if the parent is a father then the status code is 8 and if the parent is a mother then the status code is 10
I want to write a select query where I can get an output like the following:
Please help me, thanks in advance

Answer 1

You must join twice both tables table2 and table3:
select
t1.caseid, t1.caseName,
t3f.name fathername, t3f.email fatheremail,
t3m.name mothername, t3m.email motheremail
from table1 t1
left join table2 t2f on t2f.caseId = t1.caseId
inner join table3 t3f on t3f.parentid = t2f.parentid and t3f.gendercode=8
left join table2 t2m on t2m.caseId = t1.caseId
inner join table3 t3m on t3m.parentid = t2m.parentid and t3m.gendercode=10
See the demo

Answer 2

You should be able to use two sub queries from Table3 where one is for father and the other is for mother. then you can join them with case and case-parent mapping tables to get the desired output,
SELECT
C.CaseID, C.CaseName, F.Name AS FatherName, F.Email AS FatherEmail,
M.Name AS MotherName, M.Email AS MotherEmail
FROM
Table1 C
INNER JOIN
Table2 CP C.CaseID = CP.CaseID
INNER JOIN
(SELECT * FROM TABLE3 WHERE GENDERCODE = 8) F ON F.ParentID = CP.ParentID
INNER JOIN
(SELECT * FROM TABLE3 WHERE GENDERCODE = 10) M ON M.ParentID = CP.ParentID

Answer 3

You can do this with joins but it is a little more complicated than you might expect. A CTE helps:
with p as (
select t2.caseid, t3.*
from table2 t2 join
table3 t3
on t2.parentid = t3.parentid
)
select t1.*,
f.name as fathername, f.email as fatheremail
m.name mothernaem, m.email as motheremail
from table1 t1 left join
p pf
on t1.caseid = pf.caseid and pf.gendercode = 8 left join
p pm
on t1.caseid = pm.caseid and pm.gendercode = 10;
That said, conditional aggregation as proposed by fa06 also works.

Answer 4

you can use conditional aggregation with case when expression
select caseid,casename,max(case when gendercode=8 then name end) as fathername
MAX(case when gendercode=8 then email end) as fatheremail,
MAX(case when gendercode=10 then name end) as mothername,
MAX(case when gendercode=10 then email end) as motheremail
from
(
select b.caseid,c.casesname,gendercode,name,email
from table3 a inner join table2 b on a.parentid=b.parentid
inner join table1 c on b.caseid=c.caseid
)A group by caseid,casename

Answer 5

You can try like following. To combine two rows (mother and father), you can use MAX aggregate function using GROUP BY
SELECT caseid,
casename,
Max(fathername) AS fathername,
Max(fatheremail) AS fatheremail,
Max(mothername) AS mothername,
Max(motheremail) AS motheremail
FROM (SELECT t1.caseid,
t1.casename,
CASE
WHEN gendercode = 8 THEN t3.NAME
ELSE NULL
END AS fathername,
CASE
WHEN gendercode = 8 THEN t3.email
ELSE NULL
END AS fatheremail,
CASE
WHEN gendercode = 10 THEN t3.NAME
ELSE NULL
END AS mothername,
CASE
WHEN gendercode = 10 THEN t3.email
ELSE NULL
END AS motheremail
FROM table1 t1
INNER JOIN table2 t2
ON t1.caseid = t2.caseid
INNER JOIN table3 t3
ON t2.parentid = t2.parentid
WHERE t3.gendercode IN( 8, 10 ))t
GROUP BY caseid,
casename