Re: basic question about runtime query parsing

"falcon" <shahbazc@gmail.com> wrote:


# By that I mean, if someone issues 'create table(x int, y int, z int),'
# I parse it and figure out I need a struct{int x, int y, int z} (this
# struct will then be passed all over the code). How do I create this
# struct during runtime? One way I can think of is to output the struct
# definition to a file, compile it on the fly and use it. There has to
# be a better way since there are a HUGE number of langauges which use
# compile down to C and they must run into this issue regularly. I'm
# afraid the solution is stupidly simple...but somehow I've missed it.
# Any ideas?


Databases like MySQL store the row contents as a sequence of character
strings, and convert to/from character representation and internal
representation on demand.


You can use something like
typedef union {
int i;
long l;
float f;
...
} Union;
typedef Union *Row;
and then create a row with
Row r = malloc((numberOfFields)*sizeof(Union));
r[0].i = intvalue;
r[0].l = longvalue;
r[0].f = floatvalue;
...


--
SM Ryan http://www.rawbw.com/~wyrmwif/
God's a skeeball fanatic.

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