+ description => 'p.',
+ qty => 'ioi.',
+ serialnumber => 'ioi.',
+ quotation => 'apoe.',
+ cv => 'cv.',
+ "ioi.id" => ' ',
+ "ioi.ioi" => ' ',
+ );
+
+ # if the join condition in these blocks are met, the column
+ # of the scecified table will gently override (coalesce actually) the original value
+ # use it to conditionally coalesce values from subtables
+ my @column_override = (
+ # column name, prefix, joins_needed
+ [ 'description', 'ioi.', 'invoice_oi' ],
+ [ 'deliverydate', 'ioi.', 'invoice_oi' ],
+ [ 'transdate', 'apoe.', 'apoe' ],
+ [ 'unit', 'ioi.', 'invoice_oi' ],
+ [ 'sellprice', 'ioi.', 'invoice_oi' ],