Question

HQL query against a PostgreSQL database:

var checkLines = _Session.CreateQuery(
    @"select lines from FinancialStatement statement
        inner join fetch statement.FinancialStatementLines lines
    where statement.FinancialStatementId = :statementId
        and lines.TransactionType = :transactionType
        and length(lines.CheckNumber) > 0")
    .SetParameter("statementId", statement.FinancialStatementId)
    .SetParameter("transactionType", TransactionTypes.Debit)
    .List<FinancialStatementLine>();

The query looks OK to me, but I am a newbie at HQL. Can someone tell me what I’m doing wrong? I’m assuming the problem is with the HQL, please let me know if you think I need to look elsewhere.

THE PLOT THICKENS

Upon examining the query created by the above HQL, I discover it looks like this:

select 
    financials1_.LineId as LineId14_, 
    financials1_.FinancialStatementId as Financia2_14_, 
    financials1_.APPaymentID as APPaymen3_14_, 
    financials1_.EffectiveDate as Effectiv4_14_, 
    financials1_.Amount as Amount14_, 
    financials1_.TransactionType as Transact6_14_, 
    financials1_.CheckNumber as CheckNum7_14_, 
    financials1_.Description as Descript8_14_, 
    financials1_.VendorDescription as VendorDe9_14_, 
    financials1_.FinancialStatementId as Financia2_, 
    financials1_.LineId as LineId 
from 
    FinancialStatements financials0_ 
where 
    financials0_.FinancialStatementId=:p0 
    and financials1_.TransactionType=:p1 
    and length(financials1_.CheckNumber)>0

…now, WTF? The select clause aliases don’t exist in the from clause, which explains the error, but not, of course, why the error exists.

How can I work around this?

Answer 1

So here’s the deal: apparently when using HQL, to generate the right query, you need to have the object type you are trying to get as the first part of the query, for example:

var paymentLines = _Session.CreateQuery(
    @"select lines from FinancialStatementLine lines
        inner join fetch lines.Statement statement
    where statement.FinancialStatementId = :statementId
        and lines.TransactionType = :transactionType")
    .SetParameter("statementId", statement.FinancialStatementId)
    .SetParameter("transactionType", TransactionTypes.Debit)
    .List<FinancialStatementLine>();

This works, where the other query doesn’t. In SQL, the order of the joins doesn’t matter so much; in HQL, it seems quite important.