Question

I’ve been using NHibernate for a while now but mostly with convention based auto persistence model generation and then performing basic CRUD operations on the objects.

I now have that need to execute a rather nasty query against a legacy system along with a hand full of parameters (most of the where clause needs to be parameterized). I’m not clear on whether I should be defining the individual objects and then trying to implement the complex query OR simply using native SQL to define the query. I’m also not clear on the correct syntax to define the query in an hbm.xml file. The native SQL query follows. Thanks to anyone who can help me sort this out.

WITH CTE AS ( SELECT
    substr(KEY1||KEY2||KEY3||'-'||digits(KEY4)||'-'||digits(KEY5),1,17) KEY_ID,
    SUM(CASE WHEN BATCH between 200801001 and 200812999 THEN TRANSACTION_AMOUNT ELSE 0 END) AS _2008AMOUNT,
    SUM(CASE WHEN BATCH between 200901001 and 200912999 THEN TRANSACTION_AMOUNT ELSE 0 END) AS _2009AMOUNT,
    SUM(CASE WHEN BATCH between 201001001 and 201012999 THEN TRANSACTION_AMOUNT ELSE 0 END) AS _2010AMOUNT

    FROM _SCHEMA.TRANSACTIONS

    WHERE OWNER='02'
    AND TRANSACTION_TYPE in ('A','B')
    AND BATCH between 200801000 AND 201012999

    GROUP BY KEY1, KEY2, KEY3, KEY4, KEY5

    HAVING SUM(CASE WHEN BATCH between 200801001 and 200812999 THEN TRANSACTION_AMOUNT ELSE 0 END)  0
    OR SUM(CASE WHEN BATCH between 200901001 and 200912999 THEN TRANSACTION_AMOUNT ELSE 0 END)  0
    OR SUM(CASE WHEN BATCH between 201001001 and 201012999 THEN TRANSACTION_AMOUNT ELSE 0 END)  0
    )


    SELECT
    B.OWNER
    ,CTE1.MAX_ITEM_AMOUNT
    ,CTE1.SUM_ITEM_AMOUNT
    ,B.PRIMARY_SECONDARY_IDENTITY
    ,B.PRIMARY_ID
    ,B.PRIMARY_NAME
    ,B.KEY_ID
    ,B.KEY_AMOUNT
    ,CASE(B.KEYCLASS) WHEN 'C' THEN 'CLASS1' WHEN 'S' THEN 'CLASS2' WHEN 'M' THEN 'CLASS3' WHEN 'F' THEN 'CLASS4' END AS KEYCLASS
    ,NA.PRIMARY_CT AS PRIMARY_CITY
    ,NA.PRIMARY_ST AS PRIMARY_STATE
    ,B.KEY_EFFECTIVE_DATE
    ,B.KEY_ENTRY_DATE
    ,CTE._2008AMOUNT
    ,CTE._2009AMOUNT
    ,CTE._2010AMOUNT
    ,B.EMPLOYEE_NAME

    FROM CTE

    JOIN _SCHEMA.TABLE2 B ON CTE.KEY_ID = B.KEY_ID

    JOIN (
    SELECT
    PRIMARY_SECONDARY_IDENTITY
    , MAX(ITEM_AMOUNT) AS MAX_ITEM_AMOUNT
    , SUM(ITEM_AMOUNT) AS SUM_TTEM_AMOUNT
    FROM CTE
    JOIN _SCHEMA.TABLE2 B ON CTE.KEY_ID = B.KEY_ID
    GROUP BY PRIMARY_SECONDARY_IDENTITY
    ) CTE1 ON CTE1.PRIMARY_SECONDARY_IDENTITY = B.PRIMARY_SECONDARY_IDENTITY

    JOIN _SCHEMA.TABLE3 NA ON B.PRIMARY_ID = NA.KEY1 || DIGITS(NA.KEY2)

    ORDER BY MAX_ITEM_AMOUNT DESC, PRIMARY_SECONDARY_IDENTITY
    

Answer 1

This kind of transaction whatsoever shall be processed through named queries.

NHibernate allows for some pre-configured named queries which a simple CRUD operation can’t do. I suggest you take an eye out the use of these in the NHibernate documentation.

15.2. Named SQL queries

On the other hand, you may be interested in native SQL queries.

9.3.5. Queries in native SQL