Not able to update database - iphone

Question

I am not able to update one field. Please Suggest me what is the wrong thing in my code.
Code:
- (int) updateTaskDoneDate:(double)donedate ontaskid:(int)taskId
{
sqlite3 *database;
#try {
if (sqlite3_open([self.databasePath UTF8String], &database) == SQLITE_OK)
{
NSString *sql_str = [NSString stringWithFormat:#"update task set donedate='%f' where taskid=%d ", donedate ,taskId];
NSLog(#"sql str: %#",sql_str);
const char *sql = [sql_str UTF8String];
sqlite3_stmt *statement;
statement = [self PrepareStatement:sql];
NSDate *myDate;
myDate=[NSDate date];
int a1 = sqlite3_bind_double(statement, 1, [myDate timeIntervalSince1970]);
int a2 = sqlite3_bind_int(statement, 2, taskId);
NSLog(#"a1a2 %d, %d", a1, a2);
if (statement)
{
if (a1 != SQLITE_OK || a2 != SQLITE_OK)
{
sqlite3_finalize(statement);
return 0;
}
sqlite3_step(statement);
}
sqlite3_finalize(statement);
}
}
#catch (NSException *exception){
[self showException:exception];
}
#finally {
sqlite3_close(database);
return 1;
}
}

Answer 1

A couple of observations:
You're using sqlite3_bind_xxx (which is good, much better than building the SQL with stringWithFormat), but you don't have any ? placeholders in your SQL. Your SQL should presumably be:
NSString *sql_str = #"update task set donedate=? where taskid=?";
You don't need the stringWithFormat call, because you're binding your variables. You also don't need the quotes around your double value, either.
You're not showing the prepare statement, but if it fails, are you logging sqlite3_errmsg?
Likewise on your bind statements, if they're not SQLITE_OK, you're not logging sqlite3_errmsg.
Your sqlite3_step isn't checking its return code at all, much less logging sqlite3_errmsg if it's not SQLITE_DONE.
Bottom line, you must bind with ? placeholders and you're flying blind because you're not logging sqlite3_errmsg on failures.