use case when with criteria from other table without relational key - sql

Question

I have table A as seen below:
Name Amount
Bob 245.000.000
Jack 98.123.000
Mike 450.000.000
Smith 455.000.000
John 500.000.000
and table B as parameter table as
Class Range_min Range Max
<= 100 MIO 0 100000000
> 100 - 250 MIO 100000001 250000000
> 250 - 450 MIO 250000001 450000000
> 450 MIO 450000001
can somebody help me to get a result as below:
Class #ofRecord
<= 100 MIO 1
> 100 - 250 MIO 1
> 450 MIO 3
and If i modified the parameter table (the class or range), i don't need to change the query.

Answer 1

You can do this with the following statement:
SELECT [Class], COUNT(*)
FROM TableA INNER JOIN TableB
ON TableA.Amount BETWEEN COALESCE(TableB.[Range_min], TableA.Amount) AND
COALESCE(TableB.[Range Max], TableA.Amount)
GROUP BY [Class]
And you can see the working SQLFiddle as well.
Few notes:
1. You have an incorrect "requested output". "Mike" is in 250-450.
2. You really should use some naming convention to your columns. (Range_min, Range Max)

Answer 2

This is a simple join between two tables:
declare #A table (Name varchar(17) not null,Amount bigint not null)
declare #B table (Class varchar(31) not null,Range_min bigint not null,Range_Max bigint null)
insert into #A(Name,Amount) values
('Bob' ,245000000),
('Jack' ,98123000 ),
('Mike' ,450000000),
('Smith',455000000),
('John' ,500000000)
insert into #B(Class,Range_min,Range_Max) values
('<= 100 MIO' ,0 ,100000000),
('> 100 - 250 MIO',100000001,250000000),
('> 250 - 450 MIO',250000001,450000000),
('> 450 MIO' ,450000001,null )
select b.Class,COUNT(*)
from
#B b
inner join
#A a
on
b.Range_min <= a.Amount and
(
a.Amount <= b.Range_Max or
b.Range_Max is null
)
group by b.Class
Which produces the result:
Class
------------------------------- -----------
<= 100 MIO 1
> 100 - 250 MIO 1
> 250 - 450 MIO 1
> 450 MIO 2
Which doesn't match your expected result but does seem correct given the sample data.