Add WHERE clause to single column - mysql

Question

I have a query which I am working on, basically I have 3 columns:
Code: The users Code
Orders Taken: The orders which have been taken
Orders Taken From an External Call
Basically I just need a way to only allow Orders From External Calls to have a where clauses, when I add in my WHERE clause, it does it for both tables.
My query so far:
SELECT T_Temp_RestrictedDiaryCalls.AccreditedDomainCode,
Count(T_Temp_RestrictedProductSalesHistory.CustomerCode) AS [Orders Taken],
Count(T_Temp_RestrictedProductSalesHistory.CustomerCode) AS [Orders From External Calls]
FROM T_Temp_RestrictedDiaryCalls
INNER JOIN T_Temp_RestrictedProductSalesHistory
ON (T_Temp_RestrictedDiaryCalls.CustomerCode = T_Temp_RestrictedProductSalesHistory.CustomerCode)
AND (T_Temp_RestrictedDiaryCalls.CallDate = T_Temp_RestrictedProductSalesHistory.EntryDate)
GROUP BY T_Temp_RestrictedDiaryCalls.AccreditedDomainCode;
Any help will be greatly appreciated.

Answer 1

If I've got it right you should use CASE statement in the [Orders From External Calls] definition:
SELECT T_Temp_RestrictedDiaryCalls.AccreditedDomainCode,
Count(T_Temp_RestrictedProductSalesHistory.CustomerCode) AS [Orders Taken],
sum( CASE WHEN <Your condition here>
THEN 1
ELSE 0
END) AS [Orders From External Calls]
FROM T_Temp_RestrictedDiaryCalls
INNER JOIN T_Temp_RestrictedProductSalesHistory
ON (T_Temp_RestrictedDiaryCalls.CustomerCode = T_Temp_RestrictedProductSalesHistory.CustomerCode)
AND (T_Temp_RestrictedDiaryCalls.CallDate = T_Temp_RestrictedProductSalesHistory.EntryDate)
GROUP BY T_Temp_RestrictedDiaryCalls.AccreditedDomainCode;

Answer 2

Based on what you said on comments one column might have the count of all rows, and other column just show value on specify case.
So:
select table1.a,count(table1.b),
(select count(table2.c) from table2 where "where clause")
from table1

Answer 3

If I understand you correctly, you want both of those Orders columns to count data from the same table, but with different restrictions on which records from the table are counted and which are not. So do something like:
SELECT T_Temp_RestrictedDiaryCalls.AccreditedDomainCode,
Count(SalesHistoryForAllOrders.CustomerCode) AS [Orders Taken],
Count(SalesHistoryForExternalOrders.CustomerCode) AS [Orders From External Calls]
FROM T_Temp_RestrictedDiaryCalls
INNER JOIN T_Temp_RestrictedProductSalesHistory SalesHistoryForAllOrders
ON (T_Temp_RestrictedDiaryCalls.CustomerCode = SalesHistoryForAllOrders.CustomerCode)
AND (T_Temp_RestrictedDiaryCalls.CallDate = SalesHistoryForAllOrders.EntryDate)
INNER JOIN T_Temp_RestrictedProductSalesHistory SalesHistoryForExternalOrders
ON (T_Temp_RestrictedDiaryCalls.CustomerCode = SalesHistoryForExternalOrders.CustomerCode)
AND (T_Temp_RestrictedDiaryCalls.CallDate = SalesHistoryForExternalOrders.EntryDate)
GROUP BY T_Temp_RestrictedDiaryCalls.AccreditedDomainCode;
Explanation:
By INNER JOINing the table two times and aliasing it each time, we now have two separate representations of the table to work with (called SalesHistoryForAllOrders and SalesHistoryForExternalOrders).
You are then free to place a WHERE clause that refers to either one of them separately, and it will ONLY affect that column, not the other one. So either do:
WHERE SalesHistoryForExternalOrders.IsAnExternalOrder > 0
or just add an additional AND to the second INNER JOIN:
AND SalesHistoryForExternalOrders.IsAnExternalOrder > 0
, the result is the same: that clause will only be applied the External Calls column.