An Example SQLite based iPhone Application

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Link：http://www.techotopia.com/index.php/An_Example_SQLite_based_iPhone_Application

1. Creating the Database and Table

- (void)viewDidLoad {        NSString *docsDir;        NSArray *dirPaths;        // Get the documents directory        dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);        docsDir = [dirPaths objectAtIndex:0];        // Build the path to the database file        databasePath = [[NSString alloc] initWithString: [docsDir stringByAppendingPathComponent: @"contacts.db"]];        NSFileManager *filemgr = [NSFileManager defaultManager];        if ([filemgr fileExistsAtPath: databasePath ] == NO)        {                const char *dbpath = [databasePath UTF8String];                if (sqlite3_open(dbpath, &contactDB) == SQLITE_OK)                {                        char *errMsg;                        const char *sql_stmt = "CREATE TABLE IF NOT EXISTS CONTACTS (ID INTEGER PRIMARY KEY AUTOINCREMENT, NAME TEXT, ADDRESS TEXT, PHONE TEXT)";                        if (sqlite3_exec(contactDB, sql_stmt, NULL, NULL, &errMsg) != SQLITE_OK)                        {                                status.text = @"Failed to create table";                        }                        sqlite3_close(contactDB);                } else {                        status.text = @"Failed to open/create database";                }        }        [filemgr release];        [super viewDidLoad];

}

2. Implementing the Code to Save Data to the SQLite Database

- (void) saveData{        sqlite3_stmt    *statement;        const char *dbpath = [databasePath UTF8String];        if (sqlite3_open(dbpath, &contactDB) == SQLITE_OK)        {                NSString *insertSQL = [NSString stringWithFormat: @"INSERT INTO CONTACTS (name, address, phone) VALUES (\"%@\", \"%@\", \"%@\")", name.text, address.text, phone.text];                const char *insert_stmt = [insertSQL UTF8String];                sqlite3_prepare_v2(contactDB, insert_stmt, -1, &statement, NULL);                if (sqlite3_step(statement) == SQLITE_DONE)                {                        status.text = @"Contact added";                        name.text = @"";                        address.text = @"";                        phone.text = @"";                } else {                        status.text = @"Failed to add contact";                }                sqlite3_finalize(statement);                sqlite3_close(contactDB);        }

}

3. Implementing Code to Extract Data from the SQLite Database

- (void) findContact{     const char *dbpath = [databasePath UTF8String];     sqlite3_stmt    *statement;     if (sqlite3_open(dbpath, &contactDB) == SQLITE_OK)     {             NSString *querySQL = [NSString stringWithFormat: @"SELECT address, phone FROM contacts WHERE name=\"%@\"", name.text];             const char *query_stmt = [querySQL UTF8String];             if (sqlite3_prepare_v2(contactDB, query_stmt, -1, &statement, NULL) == SQLITE_OK)             {                     if (sqlite3_step(statement) == SQLITE_ROW)                     {                             NSString *addressField = [[NSString alloc] initWithUTF8String:(const char *) sqlite3_column_text(statement, 0)];                             address.text = addressField;                             NSString *phoneField = [[NSString alloc] initWithUTF8String:(const char *) sqlite3_column_text(statement, 1)];                             phone.text = phoneField;                             status.text = @"Match found";                             [addressField release];                             [phoneField release];                     } else {                             status.text = @"Match not found";                             address.text = @"";                             phone.text = @"";                     }                     sqlite3_finalize(statement);             }             sqlite3_close(contactDB);     }

}

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