SQLite not ordering data by date in iOS? - ios

Question

I have a CITIES table in which I store cityname and modifieddate. I update the date of a city by current date/time combination and when I retrieve the city names again , I am ordering the data by DATE in DESCENDING order.Now I have tried the queries on Firefox SQLite Manager and they work fine.However I can't find what going wrong here?.
This is how I retrieve data
//Retrieve data
-(NSMutableArray *)getCities{
const char *dbpath = [databasePath UTF8String];
if (sqlite3_open(dbpath, &citiesDB) == SQLITE_OK)
{
NSString *querySQL = [NSString stringWithFormat:#"SELECT cityname FROM CITIES ORDER BY modifieddate DESC"];
const char *query_stmt = [querySQL UTF8String];
NSMutableArray *resultArray = [[NSMutableArray alloc]init];
if (sqlite3_prepare_v2(citiesDB,
query_stmt, -1, &statement, NULL) == SQLITE_OK)
{
while (sqlite3_step(statement) == SQLITE_ROW)
{
NSString *name = [[NSString alloc] initWithUTF8String:
(const char *) sqlite3_column_text(statement, 0)];
[resultArray addObject:name];
NSLog(#"Result Array : %#",resultArray);
}
sqlite3_finalize(statement);
sqlite3_close(citiesDB);
return resultArray;
}else{
NSLog(#"No Cities Found");
sqlite3_finalize(statement);
sqlite3_close(citiesDB);
return nil;
}
}
return nil;
}
And this is how I update the dates for city names.
//save our data / Update the date
-(void)viewDataBaseForCity:(NSString *)cityName addedDate:(NSString *)dateAdded{
#try {
const char *dbpath = [databasePath UTF8String];
if (sqlite3_open(dbpath, &citiesDB)==SQLITE_OK)
{
NSString *querySQL = [NSString stringWithFormat:#"SELECT COUNT(CITYNAME) FROM CITIES WHERE CITYNAME ='%#'", cityName];
const char *query_stmt = [querySQL UTF8String];
if (sqlite3_prepare_v2(citiesDB, query_stmt, -1, &statement, NULL)!= SQLITE_OK)
{
NSAssert(0, #"Failed to open database");
NSLog(#"%s Prepare failure '%s' (%1d)", __FUNCTION__, sqlite3_errmsg(citiesDB), sqlite3_errcode(citiesDB));
sqlite3_finalize(statement);
sqlite3_close(citiesDB);
}
else{
if (sqlite3_step(statement)==SQLITE_ROW)
{
int count = sqlite3_column_int(statement, 0);
NSLog(#"Found city count is : %d",count);
if (count==0) {
//insert
NSString *insert_sql = [NSString stringWithFormat:#"INSERT INTO CITIES(cityname,modifieddate)VALUES (\'%#\',\'%#\')",cityName,dateAdded];
const char *insert_stmt = [insert_sql UTF8String];
sqlite3_prepare_v2(citiesDB, insert_stmt, -1, &statement, NULL);
if (sqlite3_step(statement)==SQLITE_DONE)
{
NSLog(#"Insert Successfull");
sqlite3_finalize(statement);
sqlite3_close(citiesDB);
}
else{
NSLog(#"Insert Failed"); //I also get database locked error here when tried multiple times.
NSLog(#"%s Prepare failure '%s' (%1d)", __FUNCTION__, sqlite3_errmsg(citiesDB), sqlite3_errcode(citiesDB));
sqlite3_finalize(statement);
sqlite3_close(citiesDB);
}
}else{
//update
NSString *querySQL = [NSString stringWithFormat:#"UPDATE CITIES set modifieddate ='%#' WHERE cityname='%#'", dateAdded, cityName];
const char *query_stmt = [querySQL UTF8String];
if (sqlite3_prepare_v2(citiesDB, query_stmt, -1, &statement, NULL) == SQLITE_OK)
{
NSLog(#"updated successfully");
}
sqlite3_finalize(statement);
sqlite3_close(citiesDB);
}
}else{
NSLog(#"Not Found");
}
}
}
}
#catch (NSException *exception) {
NSLog(#"SQlite exception : %#",[exception reason]);
}
#finally {
}
}
Now the date is stored as string in following format
-(NSString *)dateForCity{
NSDate *today = [NSDate date];
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:#"YYYY-MM-dd hh:mm:ss"];
NSString *dateString=[dateFormat stringFromDate:today];
return dateString;
}
Modified update query part.Which update only once and then gives database is locked error on next attempt.
//update
NSString *querySQL = [NSString stringWithFormat:#"UPDATE CITIES set modifieddate ='%#' WHERE cityname='%#'", dateAdded, cityName];
NSLog(#"Update Query : %#",querySQL);
const char *query_stmt = [querySQL UTF8String];
if (sqlite3_prepare_v2(citiesDB, query_stmt, -1, &statement, NULL) == SQLITE_OK)
{
if (sqlite3_step(statement)==SQLITE_DONE){
NSLog(#"updated successfully");
sqlite3_finalize(statement);
sqlite3_close(citiesDB);
}else{
NSLog(#"%s Update failure '%s' (%1d)", __FUNCTION__, sqlite3_errmsg(citiesDB), sqlite3_errcode(citiesDB));
sqlite3_finalize(statement);
sqlite3_close(citiesDB);
}
}

Answer 1

You are preparing the query, but not executing it for your update. Your DB is never getting the updated dates.
Additionally, you should be using arguments instead of putting the values into SQL.