CODEWITHSUNDEEP
sql-server-2008t-sqljoininner-join
response.write
response.write

Reputation: 175

Joining DISTINCT values from one table to Another

I have 7 Tables with the following structures:

tbl_Trucks             |   tbl_Driver                | tbl_Clients
-----------------------|-----------------------------|--------------------
tr_ID   - int          |   dr_ID    - int            | cl_ID   - int
tr_Name - varchar(50)  |   dr_LName - varchar(50)    | cl_Name - varchar(50)
                       |   dr_FName - varchar(50)    |
                       |   dr_MName - varchar(50)    |                       


   tbl_ExpenseHead                  |   tbl_ExpenseDiesels             
   ---------------------------------|---------------------------
   eh_ID             - int          |   dsl_ID    - int           
   eh_DateAdded      - date         |   dsl_amt   - float
   eh_RouteStart     - varchar(50)  |   dsl_Ltrs  - float
   eh_RouteEnd       - varchar(50)  |   eh_ID     - int
   cl_ID             - int          |
   dr_ID             - int          |
   tr_ID             - int          |
   eh_Status         - varchar(50)  |
   eh_ERnumber       - varchar(50)  |
   eh_InvoiceNumber  - varchar(50)  |         


   tbl_ExpenseTotal                 |   tbl_Helpers             
   ---------------------------------|---------------------------
   tot_ID            - int          |   help_ID      - int           
   tot_OverallExpense- date         |   help_FName   - varchar(50)
   eh_ID             - int          |   help_MName   - varchar(50)
                                    |   help_LName   - varchar(50)
                                    |   eh_ID        - int

currently have this query

SELECT 
h.eh_DateAdded as [TRIP_DATE],
t.tr_Name as [TRUCK_NAME],
d.dr_LName + ', ' + d.dr_FName + ' ' + d.dr_MName as DRIVER,
c.cl_Name as CLIENT,
h.eh_RouteStart + ' to ' + h.eh_RouteEnd as TRIP,
h.eh_InvoiceNumber as [INVOICE_NUMBER],
h.eh_ERnumber as [ER_NUMBER],
SUM(dsl.dsl_amt) as [DIESEL_AMOUNT],
SUM(dsl.dsl_Ltrs) as [DIESEL_LITERS],
tot.tot_OverallExpense as EXPENSE

FROM tbl_ExpenseHead h INNER JOIN 
tbl_Trucks t ON h.tr_ID = t.tr_ID INNER JOIN
tbl_Driver d ON h.dr_ID = d.dr_ID INNER JOIN
tbl_Clients c ON h.cl_ID = c.cl_ID INNER JOIN
tbl_ExpDiesels dsl ON h.eh_ID = dsl.eh_ID INNER JOIN
tbl_ExpenseTotal tot ON h.eh_ID = tot.eh_ID

WHERE h.eh_Status = 'APPROVED'
GROUP BY
h.eh_DateAdded,
t.tr_Name,
d.dr_LName,
d.dr_FName,
d.dr_MName,
c.cl_Name,
h.eh_RouteStart,
h.eh_RouteEnd,
h.eh_InvoiceNumber,
h.eh_ERnumber,
dsl.dsl_amt,
dsl.dsl_Ltrs,
tot.tot_OverallExpense

that outputs a table like this

enter image description here

as you can see, the helpers are not in the table. Given that i have tbl_Helpers populated with values like this

enter image description here

i want the first table to turn out something like this enter image description here

i want to show the helpers for each line and if it happens to have less than 2 helpers then it would be just left blank.. or NULL. I'm trying some codes here and i'm wondering if there's quick way around this. Helpers won't exceed to 2 since i restrict the user from doing so.

I tried using DISTINCT in tbl_Helpers to get each different helpers and filter them with their eh_ID's but i don't know how to get them attached to make it turn out like the third table

Upvotes: 2

Views: 65

Answers (1)

Menno
Menno

Reputation: 12621

Your first problem is you can't decide which helper should be #1 and which should be #2. So first let's assign them a number. Next, let's join them to your ExpenseHead:

WITH myHelpers AS (
    SELECT eh_ID
    , help_ID
    , RANK() OVER (PARTITION BY eh_IDORDER BY help_ID) helperOrder
    FROM tbl_Helpers
)

SELECT h.eh_ID
, hlp1.help_ID AS help1_ID
, hlp2.help_ID AS help2_ID
FROM tbl_ExpenseHead h LEFT JOIN
myHelpers hlp2 ON h.eh_ID = hlp2.eh_ID AND hlp2.helperOrder = 2 LEFT JOIN
myHelpers hlp1 ON h.eh_ID = hlp1.eh_ID AND hlp1.helperOrder = 1 AND hlp2.help_ID IS NOT NULL

Think of the WITH-statement as a temporary table which exists for the duration of the query, it's called a CTE.

Notice the use of LEFT JOIN since we don't know whether there are 2 helpers.

Notice that I only select hlp1 in case hlp2.help_ID IS NOT NULL, it's either 2 helpers or none.

Based on your example, I think you'll be able to apply this to your query. Good luck!

Upvotes: 1

Related Questions