Summing Up Unique Returned Values: A Deep Dive into CTEs and SQL Queries

In this article, we will explore how to sum up unique returned values in a SQL query. We’ll take a closer look at Common Table Expressions (CTEs), joins, and aggregations to achieve the desired result.

Understanding the Problem

The problem presented is to calculate a new column that sums up the total value of each invoice line item for a specific grouping. In this case, we’re looking for invoices with “MAG -%” fee names and a status of 1, 3, 6, or 7. The goal is to get a single row per invoice number with the sum of all corresponding fees.

SQL Query Breakdown

The provided SQL query uses a CTE (Common Table Expression) to simplify the calculation. Let’s break down the key components:

CTE (temp_cte)

with temp_cte 
as
(
    select 
        inv.INVOICENUMBER as [Invoice Number]
    , sum(comp.BASEAMOUNT) as [Total Of Fees]

    from CMCODECASEFEE ccf
        join CACOMPUTEDFEE COMP on ccf.CACOMPUTEDFEEID = comp.CACOMPUTEDFEEID
        join CAINVOICEFEE inf on comp.CACOMPUTEDFEEID = inf.CACOMPUTEDFEEID
        join CAINVOICE inv on inf.CAINVOICEID = inv.CAINVOICEID
        join CASTATUS st on inv.CASTATUSID = st.CASTATUSID

    where 
        comp.FEENAME like 'MAG -%'
    and 
        st.CASTATUSID in (1,3,6,7)
    group by inv.INVOICENUMBER
)

This CTE calculates the total amount for each invoice number based on the “MAG -%” fee name and the specified status.

Main Query

select 
    inv.INVOICENUMBER as [Invoice Number]
    , convert (date,inv.INVOICEDATE) as [Invoice Date]
    , st.name as [Invoice Status]
    , comp.FEENAME as [Fee Name]
    , comp.BASEAMOUNT as [Fee Amount Per Fee]
    , comp.AMOUNTPAIDTODATE as [Amount Paid]
    , temp_cte.[Total Of Fees]
from CMCODECASEFEE ccf
    join CACOMPUTEDFEE COMP on ccf.CACOMPUTEDFEEID = comp.CACOMPUTEDFEEID
    join CAINVOICEFEE inf on comp.CACOMPUTEDFEEID = inf.CACOMPUTEDFEEID
    join CAINVOICE inv on inf.CAINVOICEID = inv.CAINVOICEID
    join CASTATUS st on inv.CASTATUSID = st.CASTATUSID
    join temp_cte on inv.INVOICENUMBER = temp_cte.[Invoice Number]

where 
    comp.FEENAME like 'MAG -%'
and 
    st.CASTATUSID in (1,3,6,7)
and inv.INVOICEDATE between @StartDate and @EndDate

This main query joins the CTE with other tables to include additional columns. The @StartDate and @EndDate parameters are used to filter invoices based on a date range.

How It Works

1. The CTE (temp_cte) calculates the total amount for each invoice number based on the “MAG -%” fee name and the specified status.
2. The main query joins the CTE with other tables to include additional columns.
3. The query filters invoices based on a date range using the @StartDate and @EndDate parameters.

Example Use Case

Suppose we have an invoice number 17895 with two line items: $95 and $50, both with “MAG -%” fee names. We want to calculate the total amount for this invoice number.

In this case, the CTE would return:

The main query would then join this result with other tables to include additional columns.

Conclusion

Summing up unique returned values can be achieved using Common Table Expressions (CTEs) and SQL queries. By breaking down the problem into smaller components, we can create a efficient and effective solution that meets our needs. Remember to consider your specific requirements and data structure when crafting your query.

Additional Tips and Considerations

• Always test your queries thoroughly to ensure accuracy.
• Consider using indexing and caching techniques to improve query performance.
• Be mindful of database limitations and potential constraints when designing your query.
• Don’t be afraid to ask for help or seek guidance from more experienced colleagues or online resources.

Last modified on 2023-09-19