VbzCart/coding/integrity checks

Table-specific checks:

• cat_items/integrity checks

Cross-table checks

Package Lines and Order Lines which don't agree about what ID_Item they're tracking:

SELECT 
    *
FROM
    ord_pkg_lines AS pl
        JOIN
    ord_lines AS ol ON pl.ID_OrdLine = ol.ID
WHERE
    ol.ID_Item != pl.ID_Item

Package lines whose Order Line is either not set or nonexistent(!):

SELECT 
    pl.*
FROM
    ord_pkg_lines AS pl
        LEFT JOIN
    ord_lines AS ol ON pl.ID_OrdLine = ol.ID
WHERE
    ol.ID IS NULL