I thought I had this nailed with Firebird, but I'm getting some
ambiguous field name errors still with Firebird 1.5.1. These errors
don't happen in IB 6, but I understand that they are potential
problems in the queries. However I only get the error when I attempt
to do an update to the data. I've looked through the query it seems
to be complaining about and I can't find any problems with it at
all. What can I do to find out what the problem really is?

Here is one of the queries it is complaining about:

SELECT
POHEADERITEMS.SEQNO,
POHEADERITEMS.PURCHORDERID,
POHEADERITEMS.IMPORTID,
POHEADERITEMS.SELECTED,
POHEADERITEMS.JOBID,
POHEADERITEMS.WORKORDERID,
POHEADERITEMS.WORKORDERITEMID,
POHEADERITEMS.ENTITYID,
POHEADERITEMS.SPLITID,
POHEADERITEMS.TASKMATERIALID,
POHEADERITEMS.MATERIALID,
POHEADERITEMS.CHOICEID,
POHEADERITEMS.ACCOUNTID,
POHEADERITEMS.ACCOUNTID2,
POHEADERITEMS.ISEXPENSE,
POHEADERITEMS.PRICE,
POHEADERITEMS.ORDERUNITS,
POHEADERITEMS.DELIVERUNITS,
POHEADERITEMS.RECEIVEDUNITS,
POHEADERITEMS.ADDDESCRIPT,
POHEADERITEMS.LOCATION,
POHEADERITEMS.REFERENCE,
POHEADERITEMS.OVERRIDE,
POHEADERITEMS.CREATEBYNAME,
POHEADERITEMS.CREATEDON,
POHEADERITEMS.MODIFIEDBYNAME,
POHEADERITEMS.MODIFIEDON,
POHEADER.TABLEID AS POHEADER_TABLEID,
POIMPORT.TABLEID AS POIMPORT_TABLEID,
WORKORDER.TABLEID AS WORKORDER_TABLEID,
ENTITY.DESCRIPT AS ENTITY_NAME,
MATERIAL.TABLEID AS MATERIAL_TABLEID,
MATERIAL.IDCODE AS MATERIAL_IDCODE,
MATERIAL.DESCRIPT AS MATERIAL_NAME,
MATERIALUNITMEASURE.DESCRIPT AS UOM_NAME,
ACCOUNT1.IDCODE AS GLACCOUNT_IDCODE,
ACCOUNT1.NAME AS GLACCOUNT_NAME,
ACCOUNT2.IDCODE AS GLACCOUNT2_IDCODE,
ACCOUNT2.NAME AS GLACCOUNT2_NAME,
PLANPHASE.PHASEINDEX AS PLANPHASE_INDEX,
PLANPHASE.DESCRIPT AS PLANPHASE_NAME,
PLANOPTION.IDCODE AS PLANOPTION_IDCODE,
PLANOPTION.DESCRIPT AS PLANOPTION_NAME,
PROJECT.TABLEID AS PROJECT_TABLEID,
JOB.TABLEID AS JOB_TABLEID,
POHEADERITEMS.PRICE * POHEADERITEMS.ORDERUNITS AS EXT_PRICE
FROM POHEADERITEMS
LEFT OUTER JOIN POHEADER
ON (POHEADERITEMS.PURCHORDERID = POHEADER.SEQNO)
LEFT OUTER JOIN POIMPORT
ON (POHEADERITEMS.IMPORTID = POIMPORT.SEQNO)
LEFT OUTER JOIN WORKORDER
ON (POHEADERITEMS.WORKORDERID = WORKORDER.SEQNO)
LEFT OUTER JOIN ENTITY
ON (POHEADERITEMS.ENTITYID = ENTITY.SEQNO)
LEFT OUTER JOIN MATERIAL
ON (POHEADERITEMS.MATERIALID = MATERIAL.SEQNO)
LEFT OUTER JOIN MATERIALUNITMEASURE
ON (MATERIAL.TAKEOFFUM = MATERIALUNITMEASURE.SEQNO)
LEFT OUTER JOIN GLACCOUNTS ACCOUNT1
ON (POHEADERITEMS.ACCOUNTID = ACCOUNT1.SEQNO)
LEFT OUTER JOIN GLACCOUNTS ACCOUNT2
ON (POHEADERITEMS.ACCOUNTID2 = ACCOUNT2.SEQNO)
LEFT OUTER JOIN WORKORDERTAKEOFF
ON (POHEADERITEMS.WORKORDERITEMID = WORKORDERTAKEOFF.SEQNO)
LEFT OUTER JOIN PLANOPTION
ON (WORKORDERTAKEOFF.OPTIONID = PLANOPTION.SEQNO)
LEFT OUTER JOIN PLANPHASE
ON (WORKORDERTAKEOFF.PHASEID = PLANPHASE.SEQNO)
LEFT OUTER JOIN PROJECT
ON (WORKORDER.PROJECTID = PROJECT.SEQNO)
LEFT OUTER JOIN JOB
ON (POHEADERITEMS.JOBID = JOB.SEQNO)

The error is :

Ambiguous fieldname between table POHEADERITEMS and POHEADER and
table POIMPORT and table WORKORDER and table ENTITY and SEQNO.

Again this is on the update only. I'm using a IBOQuery with update,
insert, delete SQL statements in the component.

Here is the update statement:

UPDATE POHEADERITEMS
SET
SEQNO = :SEQNO,
PURCHORDERID = :PURCHORDERID,
IMPORTID = :IMPORTID,
SELECTED = :SELECTED,
JOBID = :JOBID,
WORKORDERID = :WORKORDERID,
WORKORDERITEMID = :WORKORDERITEMID,
ENTITYID = :ENTITYID,
SPLITID = :SPLITID,
TASKMATERIALID = :TASKMATERIALID,
MATERIALID = :MATERIALID,
CHOICEID = :CHOICEID,
ACCOUNTID = :ACCOUNTID,
ACCOUNTID2 = :ACCOUNTID2,
ISEXPENSE = :ISEXPENSE,
PRICE = :PRICE,
ORDERUNITS = :ORDERUNITS,
DELIVERUNITS = :DELIVERUNITS,
RECEIVEDUNITS = :RECEIVEDUNITS,
ADDDESCRIPT = :ADDDESCRIPT,
LOCATION = :LOCATION,
REFERENCE = :REFERENCE,
OVERRIDE = :OVERRIDE,
CREATEBYNAME = :CREATEBYNAME,
CREATEDON = :CREATEDON,
MODIFIEDBYNAME = :MODIFIEDBYNAME,
MODIFIEDON = :MODIFIEDON
WHERE
SEQNO = :OLD_SEQNO