LEFT JOINS in MS Access - sql

Question

I am trying to troubleshoot someone else's MS Access query and keep getting an invalid operation error. The Help doesn't seem to apply as I am just running a query. It all works as INNER JOINS but when I switch back to the LEFT JOIN the error.
SELECT *
FROM ((((orders
INNER JOIN orders_customers ON orders.CUST_ORDER_ID = orders_customers.ID)
LEFT JOIN quoted_theory ON orders.PART_ID = quoted_theory.PART_ID)
LEFT JOIN conversions ON orders.PART_ID = conversions.PART_ID)
LEFT JOIN dbo_WO_Header ON orders.CUST_ORDER_ID = dbo_WO_Header.PPC_Number)
INNER JOIN lines_qry ON orders.CUST_ORDER_ID = lines_qry.WORKORDER_BASE_ID
I can get one level of LEFT JOIN, but each time I add a second LEFT JOIN the error pops up.

Answer 1

Access' db engine frequently balks when mixing INNER and LEFT joins. If that query works without the last inner join ...
SELECT *
FROM
(((orders INNER JOIN orders_customers
ON orders.CUST_ORDER_ID = orders_customers.ID)
LEFT JOIN quoted_theory
ON orders.PART_ID = quoted_theory.PART_ID)
LEFT JOIN conversions
ON orders.PART_ID = conversions.PART_ID)
LEFT JOIN dbo_WO_Header
ON orders.CUST_ORDER_ID = dbo_WO_Header.PPC_Number
... then you could try that part as a subquery and inner join lines_qry to the subquery. It might get past the error.
SELECT *
FROM
(
SELECT *
FROM
(((orders INNER JOIN orders_customers
ON orders.CUST_ORDER_ID = orders_customers.ID)
LEFT JOIN quoted_theory
ON orders.PART_ID = quoted_theory.PART_ID)
LEFT JOIN conversions
ON orders.PART_ID = conversions.PART_ID)
LEFT JOIN dbo_WO_Header
ON orders.CUST_ORDER_ID = dbo_WO_Header.PPC_Number
) AS sub
INNER JOIN lines_qry
ON sub.CUST_ORDER_ID = lines_qry.WORKORDER_BASE_ID
If any other table besides orders includes a field named CUST_ORDER_ID, you will need something other than SELECT * within the subquery to avoid ambiguity.

Answer 2

SELECT *
FROM
(
SELECT *
FROM
(((orders INNER JOIN orders_customers
ON orders.CUST_ORDER_ID = orders_customers.ID)
LEFT JOIN quoted_theory
ON orders.PART_ID = quoted_theory.PART_ID)
LEFT JOIN conversions
ON orders.PART_ID = conversions.PART_ID)
LEFT JOIN dbo_WO_Header
ON orders.CUST_ORDER_ID = dbo_WO_Header.PPC_Number
) AS sub
INNER JOIN lines_qry
ON sub.CUST_ORDER_ID = lines_qry.WORKORDER_BASE_ID