Question

I have three tables that contain data relating to a Job. One table is a master table and the other two are transactional and are related to the master.

CREATE TABLE Job
(JobNo varchar(10))

CREATE TABLE Trans1
(JobNo varchar(10), TrxDate datetime, TrxStatus int)

CREATE TABLE Trans2
(JobNo varchar(10), TrxDate datetime, TrxStatus int)

The Job table will always have one row per job. Trans1 and Trans2 will have none, one or many rows per job.

I need to be able to write a query that will return, for a given job, what the TrxStatus column’s value was on a given date.

Let’s say Trans1 has

Job     TrxDate    TrxStatus
AB123   2/1/2012     10
AB123   3/1/2012     20
AB123   3/31/2021    20

Let’s say Trans2 has

Job    TrxDate   TrxStatus
AB123  3/15/2012   10

I need to be able to create a function (or have a solution) where I can query:

SELECT JobNo, GetStatusAt(JobNo, '3/1/2012') FROM Job

and have it return 20.

SELECT JobNo, GetStatusAt(JobNo, '3/17/2012') FROM Job

and have it return 10.

SELECT JobNo, GetStatusAt(JobNo, '4/1/2012') FROM Job

and have it return 20.

Answer 1

SELECT  TOP 1
        trxStatus
FROM    (
        (
        SELECT  TOP 1
                *
        FROM    trans1
        WHERE   jobNo = @job
                AND trxDate <= @trxDate
        ORDER BY
                trxDate DESC
        )
        UNION ALL
        (
        SELECT  TOP 1
                *
        FROM    trans2
        WHERE   jobNo = @job
                AND trxDate <= @trxDate
        ORDER BY
                trxDate DESC
        )
        ) q
ORDER BY
        trxDate DESC