But there is still scope for avoiding inefficient queries. One general rule is to place the most restrictive query first, this reduces the work for subsequent SQL checks. Making such recommendations is strictly outside of the scope of a portability checker. Vendor extensions Use of all vendor extensions to SQL are flagged. Where possible a standard construct is suggested.
Vendors implement it differently.
Calls to inbuilt library routines were relatively easy to support. It is possible to treat each embedded SQL statement as a standalone entity. One of the first priorities was to reduce the number of false warnings emitted by the uninitialised variable checking. OSPC takes a worst case approach to this problem, so the number of false warnings was already considered high. Embedded SQL may also read from C variables and checking was added to ensure that values had been assigned to them.