Using stringWithFormat for query setup
Not entirely sure why this isn't working.
sqlite3 *db;
sqlite3_open([databasePath UTF8String], &db);
NSString *query;
NSNumber *start = (*cur_page * 50) - 50;
query = [NSString stringWithFormat:@"SELECT rest_db.rest_id, rest_db.name, prices.value FROM rest_db JOIN prices ON rest_db.rest_id = prices.table_id WHERE prices.table_name = 'rest_db' ORDER BY rest_db.name ASC %d Limit 50;", start];
Previously, the code looked like:
sqlite3 *db;
sqlite3_open([databasePath UTF8String], &db);
NSString *query;
query = @"SELECT rest_db.rest_id, rest_db.name, prices.value FROM rest_db JOIN prices ON rest_db.rest_id = prices.table_id WHERE prices.table_name = 'rest_db' ORDER BY rest_db.name ASC";
which worked just fine. I've tried setting start as:
int start
int *start
NSString *start
and of course I changed the "%d" accordingly for the string. All to no avail. I'm clueless at the moment. The program crashes when I hit this page now. No errors, can't get anything to write using NSLog.
I've also tried using:
[NSString alloc] initWithFormat
Any ideas? They are appreciated. Thanks.
----------------------------- EDIT ----------------------------
.h
int page_count;
int cur_page;
@property int page_count;
@property int cur_page;
.m
@synthesize page_count;
@synthesize cur_page;
int start = (cur_page * 50) - 50;
query = [NSString stringWithFormat:@"SELECT rest_db.rest_id, rest_db.name, prices.value FROM rest_db JOIN prices ON rest_db.rest_id = prices.table_id WHERE prices.table_name = 'rest_db' ORDER BY rest_db.name ASC %d Limit 50;", start];
And now, since I did fix a typecast thanks to one of the previous suggestions, it doesn't crash the program, but shows no data from the query as start = 0. Which as I look over my code is exactly what it should equal, and if I had my sqlite statement set up correctly, I would see that I am putting it into the limit in the wrong place... -.- So the initial typecast开发者_运维知识库 issue was the crash and only issue, it would seem.
I suspect that NSNumber *start = (*cur_page * 50) - 50;
is calculating an integer value and then assigning that int value to the pointer start
, producing an invalid pointer. start
should be declared as an int
or NSInteger
.
Try using %@ instead of %d. %d is for integers; NSNumber is an objective-c object.
Also, instead of
NSNumber *start = (*cur_page * 50) - 50;
try
NSNumber *start = [NSNumber numberWithInt:([cur_page intValue] * 50) - 50];
Assuming cur_page is of type NSNumber*.
http://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/nsnumber_Class/Reference/Reference.html
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