Hello!
I'm using the function from SQLite tests:
static void counterFunc(
sqlite3_context *pCtx, /* Function context */
int nArg, /* Number of function arguments */
sqlite3_value **argv /* Values for all function arguments */
){
int i;
int *pCounter;
pCounter = (int*)sqlite3_get_auxdata(pCtx, 0);
if( pCounter==0 ){
pCounter = sqlite3_malloc( sizeof(*pCounter) );
if( pCounter==0 ){
sqlite3_result_error_nomem(pCtx);
return;
}
*pCounter = sqlite3_value_int(argv[0]);
sqlite3_set_auxdata(pCtx, 0, pCounter, sqlite3_free);
}else{
++*pCounter;
}
sqlite3_result_int(pCtx, *pCounter);
}
But the result is strange:
sqlite> select value=0,counter(0),counter(value=0) from state;
0|0|0
0|1|0
0|2|0
0|3|0
0|4|0
0|5|0
0|6|0
0|7|0
0|8|0
0|9|0
0|10|0
0|11|0
0|12|0
Of course I need to get the result of counter(value==0) equal to counter(0).
The result of "value=0" is always 0 and so counter(value=0) may be identical
to counter(0).
P.S. I want build function similar to linux "uniq" utility:
select value from state where uniq(value)=1;
This can emulate "distinct on" clause too.
Best regards, Alexey Pechnikov.
http://pechnikov.tel/
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