If Statements in where clause? - sql

Question

So I have to run a query against a database schema: http://sqlfiddle.com/#!9/d0b643 , but an example schema would look like:
Table 1
itemID sale date salesmanID storeID
---------------------------------------------------
1 1/2015 1 1
1 3/2016 1 1
2 5/2016 2 1
2 1/2015 4 1
Table 2
itemID colorID price
--------------------------------------
1 1 23
1 2 10
1 3 13
2 1 11
2 2 14
2 3 18
Table 3
ColorID color
---------------------------------------
1 Red
2 Blue
3 Green
Table 4
SaleBegin SaleEnd ColorID salesmanID storeID
----------------------------------------------------------------
1/1/2014 12/31/2014 1 0 1
1/1/2015 12/31/2015 2 0 1
1/1/2016 12/31/2016 3 0 1
1/1/2014 12/31/2014 3 2 1
1/1/2015 12/31/2016 2 2 1
I need to have something in the where clause that pretty much says if there is a SalesmanID and the saleDate from Table1 falls between the StartDate and Enddate of Table4, use that color. Otherwise, if there is no salesmanID, use the StoreID (in this example they are all 1, but they could be different).
The current query I am adding this to is:
select t1.itemID,t3.color,t2.price
from table_1 t1
LEFT JOIN table_2 t2
ON t1.itemID = t2.itemID
LEFT JOIN table_3 t3
ON t2.colorID = t3.colorID
LEFT JOIN table_4 t4
ON t3.colorID = t4.colorID
WHERE t1.sale_date BETWEEN saleBegin and saleEnd;
How can I run this? The expected results should look like:
itemID color price
1 Blue 10
1 Green 13
2 Blue 14
2 Blue 14

Answer 1

I am trying to use MSSQL logic. and try it in SQL fiddle it run success.
Just try this code yourself to see if this is what you want.
select t1.itemID,t3.color,t2.price from table_1 t1
LEFT JOIN table_4 t41
on t1.sale_date BETWEEN t41.saleBegin and t41.saleEnd
and t41.salesmanID!=0 and t1.salesmanID=t41.salesmanID
LEFT JOIN table_4 t42
on t1.sale_date BETWEEN t42.saleBegin and t42.saleEnd
and t42.salesmanID=0 and t1.storeID=t42.storeID
INNER JOIN table_2 t2
ON t1.itemID = t2.itemID
INNER JOIN table_3 t3
ON t2.colorID = t3.colorID and t2.colorID=IF(ISNULL(t41.colorID),t42.colorID,t41.colorID)
order by t1.itemID,t3.color,t2.price;

Answer 2

I think this is what you want. You will get too many rows because of overlaps between store # and Sale dates. Once I changed your sample data table4 to have the last two rows be store #2 I get the results you posted.
1/1/2014 12/31/2014 3 2 2
1/1/2015 12/31/2016 2 2 2
Select t1.itemID,t3.color,t2.price
From table_1 t1
LEFT JOIN table_4 t4 ON t1.sale_date BETWEEN t4.saleBegin And t4.saleEnd And t1.SalesmanID = t4.SalesmanID
LEFT JOIN table_4 t4a ON t1.sale_date BETWEEN t4a.saleBegin And t4a.saleEnd And t1.StoreID = t4a.StoreID
LEFT JOIN table_2 t2 ON t1.itemID = t2.itemID And t2.ColorID = t4a.ColorID
LEFT JOIN table_3 t3 ON t2.colorID = t3.colorID
Where t4.SalesmanID Is Null
Group By t1.itemID,t3.color,t2.price
Union All
Select t1.itemID,t3.color,t2.price
From table_1 t1
LEFT JOIN table_4 t4 ON t1.sale_date BETWEEN t4.saleBegin And t4.saleEnd And t1.SalesmanID = t4.SalesmanID
LEFT JOIN table_2 t2 ON t1.itemID = t2.itemID And t2.ColorID = t4.ColorID
LEFT JOIN table_3 t3 ON t2.colorID = t3.colorID
Where t4.SalesmanID Is Not Null
itemID color price
1 Blue 10.000
1 Green 13.000
2 Blue 14.000
2 Blue 14.000