Question

I am new to iPhone development. I want to insert certain data into my database and retrieve it
and display it in a table. I have created Database data.sqlite with table ‘user’. The table has two values, id(varchar) and name(varchar). I have inserted 3 rows of data in the table via “insert into user value(‘1′,’xxxx’);” in the terminal window. I have created a navigation based applicaton named “testDb”. In AppDelegate I have two methods

- (void)createEditableCopyOfDatabaseIfNeeded {
    NSLog(@"Creating editable copy of database");
    // First, test for existence.
    BOOL success;
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSError *error;
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@"data.sqlite"];
    success = [fileManager fileExistsAtPath:writableDBPath];
    if (success) return;
    // The writable database does not exist, so copy the default to the appropriate location.
    NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"data.sqlite"];
    success = [fileManager copyItemAtPath:defaultDBPath toPath:writableDBPath error:&error];
    if (!success) {
        NSAssert1(0, @"Failed to create writable database file with message '%@'.", [error localizedDescription]);
    }
}

and

+(sqlite3 *) getNewDBConnection{
    sqlite3 *newDBconnection;
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *path = [documentsDirectory stringByAppendingPathComponent:@"data.sqlite"];
    // Open the database. The database was prepared outside the application.
    if (sqlite3_open([path UTF8String], &newDBconnection) == SQLITE_OK) {
        NSLog(@"Database Successfully Opened :)");
    }
    else {
        NSLog(@"Error in opening database :(");
    }
    return newDBconnection;
}

In rootviewcontroller

-(void)initializeTableData{
    sqlite3 *db=[DatabaseTestAppDelegate getNewDBConnection];
    sqlite3_stmt *statement=nil;
    const char *sql="select * from user";
    if (sqlite3_prepare_v2(db, sql, -1, &statement, NULL)!=SQLITE_OK)
        NSAssert1(0,@"error in preparing staement",sqlite3_errmsg(db));
    else {
        while(sqlite3_step(statement)==SQLITE_ROW)
            [tableData addObject:[NSString stringWithFormat:@"%s",(char*)sqlite3_column_text(statement,1)]];
    }
    sqlite3_finalize(statement);
}

- (void)viewDidLoad {
    [super viewDidLoad];
    tableData=[[NSMutableArray alloc]init];
    [self addMyObjectIntoDatabase];
    [self initializeTableData];
    self.title=@"Database test";
}

To display the contents

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
    }
    NSLog(@"before displaying data");
    cell.textLabel.text=[tableData objectAtIndex:indexPath.row];
    NSLog(@"after displaying data");
    // Configure the cell.
    return cell;
}

This is working fine to display the content of table. But now I want to insert another row into my table and display the inserted content along with previous content. Since I am new to iPhone I learnt from tutorials to read the database and display its contents. How do I proceed further to my task of inserting and displaying again?

Answer 1

If you’re really interested in learning how to use SQLite to manage data in an iPhone app, I would recommend you to complete the following tutorial, as it’s a very good introduction:

iphone-programming-tutorial-creating-a-todo-list-using-sqlite-part-1

The tutorial handles Selecting, Updating, Inserting and Deleting data in an iPhone app, using SQLite.