How to combine multiple tables with the basic ID of one table - sql

Question

I want to combine 5 multiple tables, that have the same reference ID as the basic table containing all IDs. The "joined" tables are not containing a value for every reference, but sometimes they have multiple values for one reference. The output should be a sum of each value of the ID.
Example:
Basic Table:
Reference
Basic.Value
1
a
2
b
3
c
4
d
5
e
6
f
7
g
8
h
Table 1:
Reference
T1.Value
1
i
2
j
2
x
3
k
4
l
Table 2
Reference
T2.Value
1
m
5
n
7
o
7
y
8
p
Table 3
Reference
T3.Value
2
q
4
r
6
s
8
t
8
z
Result that should be the output:
Reference
Basic.Value
SUM(T1.Value)
SUM(T2.Value)
SUM(T3.Value)
1
a
i
m
2
b
(j+x)
q
3
c
k
4
d
l
r
5
e
n
6
f
s
7
g
(o+y)
8
h
p
(t+z)
I tried the following code:
SELECT
T0."STATUS",
T0."DocNum" AS "ProjectNumber",
T0."NAME", T0."CARDNAME" AS "Client",
T0."FINISHED" AS "Project Finished",
T1."PoPhAmt" AS "Project Value",
T1."PhBudget" AS "Budget",
(T1."PoPhAmt"-T1."PhBudget") AS "Planned Gross Profit",
T1."TotalAP" AS "Ordered",
SUM(T2."PaidSys") AS "Paid Downpayments(Client)",
COUNT(T2."PaidSys"),
SUM(T3."PaidSys") AS "Paid Invoices(Client)",
COUNT(T3."PaidSys"),
SUM(T4."PaidSys") AS "Creditnotes(Client)",
COUNT(T4."PaidSys")
FROM
(OPMG T0 INNER JOIN PMG8 T1 ON T0."AbsEntry" = T1."AbsEntry")
LEFT JOIN ODPI T2 ON T0."FIPROJECT" = T2."Project"
LEFT JOIN OINV T3 ON T0."FIPROJECT" = T3."Project"
LEFT JOIN ORIN T4 ON T0."FIPROJECT" = T4."Project"
WHERE
T0."FINISHED" < '100' AND T0."STATUS" <> 'N' AND T0."STATUS" <> 'P'
GROUP BY
T0."STATUS",
T0."DocNum",
T0."NAME",
T0."CARDNAME",
T0."FINISHED" ,
T1."PoPhAmt",
T1."PhBudget",
T1."TotalAP"
ORDER BY
T0."DocNum"

Answer 1

Aggregate before joining:
select *
from basic_table t left join
(select t1.project, count(*) as cnt1, sum(value) as value1
from t1
group by t1.project
) t1
on t.FIPROJECT = T1.Project left join
(select t2.project, count(*) as cnt2, sum(value) as value2
from t2
group by t2.project
) t2
on t.FIPROJECT = T2.Project left join
(select t3.project, count(*) as cnt3, sum(value) as value3
from t3
group by t3.project
) t3
on t.FIPROJECT = T3.Project;

Answer 2

SELECT T.ID,T.VALUE,T1.VALUE T_1_VALUE,T2.VALUE T_2_VALUE,T3.VALUE T_3_VALUE
FROM BASIC_TABLE T
LEFT JOIN TABLE_1 T1 ON T.ID=T1.ID
LEFT JOIN TABLE_2 T2 ON T.ID=T2.ID
LEFT JOIN TABLE_3 T3 ON T.ID=T3.ID

Answer 3

WITH BASIC_TABLE(REFERENCE,BASIC_VALUE) AS
(
SELECT 1, 'a' UNION ALL
SELECT 2 , 'b' UNION ALL
SELECT 3 , 'c' UNION ALL
SELECT 4 , 'd' UNION ALL
SELECT 5 , 'e' UNION ALL
SELECT 6 , 'f' UNION ALL
SELECT 7 , 'g' UNION ALL
SELECT 8 , 'h'
),
TABLE_1(REFERENCE,T1_VALUE) AS
(
SELECT 1, 'i' UNION ALL
SELECT 2, 'j' UNION ALL
SELECT 2, 'x' UNION ALL
SELECT 3, 'k' UNION ALL
SELECT 4, 'l'
),
TABLE_2(REFERENCE,T2_VALUE)AS
(
SELECT 1, 'm' UNION ALL
SELECT 5, 'n' UNION ALL
SELECT 7, 'o' UNION ALL
SELECT 7, 'y' UNION ALL
SELECT 8 , 'p'
),
TABLE_3(REFERENCE,T3_VALUE)AS
(
SELECT 2, 'q' UNION ALL
SELECT 4, 'r' UNION ALL
SELECT 6, 's' UNION ALL
SELECT 8, 't' UNION ALL
SELECT 8, 'z'
)
SELECT B.REFERENCE,B.BASIC_VALUE,ISNULL(T1.R,'')AS SUM_T_1_VALUE,ISNULL(T2.R,'')AS SUM_T_2_VALUE,
ISNULL(T3.R,'')AS SUM_T_3_VALUE
FROM BASIC_TABLE AS B
LEFT JOIN
(
SELECT T.REFERENCE,STRING_AGG(T.T1_VALUE,'+')R
FROM TABLE_1 AS T
GROUP BY T.REFERENCE
)T1 ON B.REFERENCE=T1.REFERENCE
LEFT JOIN
(
SELECT T.REFERENCE,STRING_AGG(T.T2_VALUE,'+')R
FROM TABLE_2 AS T
GROUP BY T.REFERENCE
)T2 ON B.REFERENCE=T2.REFERENCE
LEFT JOIN
(
SELECT T.REFERENCE,STRING_AGG(T.T3_VALUE,'+')R
FROM TABLE_3 AS T
GROUP BY T.REFERENCE
)T3 ON B.REFERENCE=T3.REFERENCE
Not sure about SAP HANA, but in MS SQL Server 2017 this code produces more or less the required output

Answer 4

use following query STRING_AGG function with group by Basic_Table.Reference
SELECT
T.Reference,
MAX(T.Basic_Value) AS Basic_Value,
SUM(T1.T1_Value) AS T1_Value,
SUM(T2.T2_Value) AS T2_Value,
SUM(T3.T3_Value) AS T3_Value
FROM BASIC_TABLE T
LEFT JOIN TABLE_1 T1 ON T.Reference=T1.Reference
LEFT JOIN TABLE_2 T2 ON T.Reference=T2.Reference
LEFT JOIN TABLE_3 T3 ON T.Reference=T3.Reference
GROUP BY T.Reference