Phase 2: Make SPs belong to a DB, and use qualified names.
As a side effect, using USE in an SP is no longer allowed.
(It just doesn't work otherwise.)
make characteristics (and SHOW) work right, we had to separate the old
definition blob in the mysql.proc table into separate fields for parameters,
return type, and body, and handle the characteristics (like SQL SECURITY)
separately... and then reassemble the CREATE string for parsing, of course.
This is rather ugly, mostly the parser bit. (Hopefully that will be better
with the new parser.)
Expanded the mysql.proc table, reworked the find/create/drop functions
completely, added new functions for FUNCTIONs (lotta functions here :),
got rid of some unnecessary use of Item_strings while at it. Extended
the parser correspondingly, and fiddled around a bit to make SP FUNCTIONs
coexist with UDFs.
Can now CREATE and DROP FUNCTIONs. Invoking yet to come...
Fixed backpatching of forward jumps.
Implemented LOOP, WHILE, REPEAT (temporarily known as SPREPEAT).
Known bug: Expression evaluation still not quite ok (e.g. "x > 0"),
which is why IF and CASE is not yet implemented.
