SQLite suddenly not responding in iPhone app - iphone

Question

I have a massive problem with SQLite in my iPhone app, that needs to be fixed for a client soon! Basically i'm pulling a column from a database and loading it into a table view on viewWillAppear. It works fine, for the first few times the view is loaded but then suddenly it starts return empty (null) values. Upon inspection it appears that there is an issue with opening the database maybe but this is my first SQLite project so it's hard to figure out what's going on.
Here is the code I use to pull the SQL information:
+ (void) getInitialDataToDisplay:(NSString *)dbPath {
NSLog(#"INCOME CALLED 1");
NavTabAppDelegate *appDelegate = (NavTabAppDelegate *)[[UIApplication sharedApplication] delegate];
appDelegate.incomeArray = [[NSMutableArray alloc] init];
if (sqlite3_open([dbPath UTF8String], &database) == SQLITE_OK) {
NSLog(#"INCOME CALLED 2");
const char *sql = "select IncomeID, IncomeName from Income ORDER BY IncomeName asc";
//const char *sql2 = "select categoryID, Size from coffee";
sqlite3_stmt *selectstmt;
if(sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL) == SQLITE_OK) {
NSLog(#"INCOME CALLED 3");
while(sqlite3_step(selectstmt) == SQLITE_ROW) {
NSLog(#"INCOME CALLED 4");
NSInteger primaryKey = sqlite3_column_int(selectstmt, 0);
Income *incomeObj = [[Income alloc] initWithPrimaryKey:primaryKey];
//This is how I pull info from the database using the above select statement and setting it in the coffeeObj property of Coffee class
incomeObj.incomeName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt, 1)];
//coffeeObj.coffeeSize = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt, 2)];
incomeObj.isDirty = NO;
[appDelegate.incomeArray addObject:incomeObj];
[incomeObj release];
NSLog(#"INCOME OBJECTS %#", incomeObj.incomeName);
//NSLog(#"CALLED");
}
}
}
else{
sqlite3_close(database); //Even though the open call failed, close the database connection to release all the memory
NSLog(#"INCOME CALLED 5");
}
NSLog(#"INCOME CALLED 6");
}
I am calling the code in viewWillAppear as follows:
[Income getInitialDataToDisplay:[appDelegate getDBPath]];
Also this is the output from my console when the error occurs:
2011-06-17 12:21:48.307 CashCal[318:707] GET DB PATH CALLED
2011-06-17 12:21:48.310 CashCal[318:707] /var/mobile/Applications/2BD7CA1D-C7AB-4425-B5C1-974C4F4D057C/Documents/SQL.sqlite
2011-06-17 12:21:48.312 CashCal[318:707] INCOME CALLED 1
2011-06-17 12:21:48.314 CashCal[318:707] INCOME CALLED 5
2011-06-17 12:21:48.318 CashCal[318:707] INCOME CALLED 6
It appears the problem is with the first if statement opening the database. I really need help on this one

Answer 1

You should always destroy prepared statements by calling sqlite3_finalize(your_stmt). And you should always close youre connection not only if it sqlite3_open() failed.
Also do something like this:
if(sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL) == SQLITE_OK) {
//your code here
} else {
//print error
NSLog(#"sql-error: %s", sqlite3_errmsg(database));
}
for clarification, here a interface for your db, that should avoid opening the db when its allready open, and makes code cleaner
DBi.h
#import <Foundation/Foundation.h>
#import <sqlite3.h>
#interface DBi : NSObject {
sqlite3* db;
}
- (void)opendDB;
- (void)closeDB;
- (NSArray*)getIcons;
#end
DBi.m
#import "DBi.h"
#import "Income.h"
static DBi *sharedDBi = nil;
#implementation DBi
- (void)dealloc {
sqlite3_close(db);
[super dealloc];
}
+ (DBi*)sharedManager {
if (sharedDBi == nil) {
sharedDBi = [[super allocWithZone:NULL] init];
[sharedDBi opendDB];
}
return sharedDBi;
}
+ (id)allocWithZone:(NSZone *)zone {
return [[self sharedManager] retain];
}
- (void)opendDB {
NSString *dbPath = [[NSBundle mainBundle]pathForResource:#"path_to_db_file"ofType:#"sqlite"];
//open the database
if(!sqlite3_open([dbPath UTF8String], &db) == SQLITE_OK) {
NSLog(#"connection to db failed");
sqlite3_close(db);
}
}
- (void)closeDB {
sqlite3_close(db);
}
- (NSArray*)getIncoms {
NSMutableArray rArray = [[[NSMutableArray alloc] init] autorelease];
const char *sql = "select IncomeID, IncomeName from Income ORDER BY IncomeName asc";
//const char *sql2 = "select categoryID, Size from coffee";
sqlite3_stmt *selectstmt;
if(sqlite3_prepare_v2(db, sql, -1, &selectstmt, NULL) == SQLITE_OK) {
while(sqlite3_step(selectstmt) == SQLITE_ROW) {
NSInteger primaryKey = sqlite3_column_int(selectstmt, 0);
Income *incomeObj = [[Income alloc] initWithPrimaryKey:primaryKey];
incomeObj.incomeName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt, 1)];
incomeObj.isDirty = NO;
[rArray addObject:incomeObj];
[incomeObj release];
}
} else {
NSLog(#"sql-error in getIncoms: %s", sqlite3_errmsg(db));
}
sqlite3_finalize(selectstmt);
return rArray;
}
Now you could do something like that.
DBi *dbi = [[DBi alloc] init];
NSArray *incoms = [dbi getIncoms];
[dbi release];
hope, that should help

Answer 2

use this code
sqlite3 *database;
if(sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK)
{
////your Code
if(sqlite3_prepare_v2(database, [sqlStatement cStringUsingEncoding:NSUTF8StringEncoding], -1, &compiledStatement, NULL) == SQLITE_OK)
{
NSLog(#"%#",sqlStatement);
while(sqlite3_step(compiledStatement) == SQLITE_ROW)
{
//your code
}
}
sqlite3_finalize(compiledStatement);
sqlite3_close(database);
}
}

Answer 3

Use FMDB for you sqlite tasks. It's a bad practice to use sqlite calls everywhere in the application. Just search on google for FMDB Example you will find one. FMDB is much easier to implement then SQLIte because FMDB handles all the things.

Answer 4

It turns out I was calling the same SQL method in two different places in very quick succession before the statements had a chance to be finalised each time. I guess this caused some sort of overlap eventually leading to the statements becoming invalid. Thanks for all the help. I will definitely be using CoreData or FMDB next time.