如何創建一個SQLite

Question

如何創建源碼文件時，應用程序啓動（didFinishLaunchingWithOptions），如果它已經與否exsist否則創建該文件的SQLite

Answer 1

像這樣的測試...的SQLPATH變量是路徑您的ressource預先做好的SQL數據庫

- (void) checkAndCreateSQL 
{ 
    if (![[NSFileManager defaultManager] fileExistsAtPath:[documentPath stringByAppendingString:@"/database.sql"]]) { 
     [[NSFileManager defaultManager] createFileAtPath:[documentPath stringByAppendingString:@"/database.sql"] 
               contents:[NSData dataWithContentsOfFile:sqlPath] 
               attributes:nil]; 
    } 
} 

編輯1：

您可以使用此命令行創建你的Mac數據庫：

sqlite3 database.sql < DATABASE_CREATION.txt 

在DATABASE_CREATION.txt像這樣

：

CREATE TABLE IF NOT EXISTS `group` (
    `id` integer PRIMARY KEY, 
    `name` text, 
    `position` integer 
); 

然後把直接database.sql文件到您的項目資源。 （如圖像）

Answer 2

你可能想使用默認的核心數據庫，而不是手動創建和處理一個單一的SQLite文件。請檢查官方Apple Core Data Programming Guide。它會自動處理應用程序內部數據庫的創建和更新。

Answer 3

sqlite3 *reference2Database() { 
if (_database == nil) { 
    // First, test for existence. 
    NSError *error; 
    NSFileManager *fileManager = [NSFileManager defaultManager]; 
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsDirectory = [paths objectAtIndex:0]; 
    NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@"my.sqlite"]; 

    if ([fileManager fileExistsAtPath:writableDBPath] == NO) { 
     // Database file doesnt exists. Copy the database at writable path (documents directory). 
     NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"my.sqlite"]; 

     [fileManager removeItemAtPath:writableDBPath error:nil]; 

     BOOL databaseCopied = [fileManager copyItemAtPath:defaultDBPath toPath:writableDBPath error:&error]; 
     if (!databaseCopied) { 
      // Handle the error... 
     } 
    }else { 
     // Open the database. The database was prepared outside the application. 
     if (sqlite3_open([writableDBPath UTF8String], &_database) != SQLITE_OK) { 
      // Even though the open failed, call close to properly clean up resources. 
      sqlite3_close(_database); 
      _database = nil; 
      // Additional error handling, as appropriate... 
     } 
    } 
} 
return _database; 
} 

//樣例用法。

-(void) someDatabaseFunction { 
    sqlite3 *database = reference2Database(); 
    // Do something with "database"... 
} 

//關閉數據庫。這應該在應用程序終止時調用。

void closeDatabase() { 
if (_database == nil) return; 
// Close the database. 
if (sqlite3_close(_database) != SQLITE_OK) { 
    // Handle the error... 
} 
_database = nil; 

}

注：在該文件的頂部，你應該有：靜態sqlite3的* _database =零;

Answer 4

我用Matteo Bertozzi's SQLite Wrapper與下面的代碼創建我的SQLite數據庫：

-(void)checkDatabase 
{ 
    if([[NSFileManager defaultManager] fileExistsAtPath:DBPATH] == NO) 
    { 
     sqlite = [[Sqlite alloc] init]; 

     if (![sqlite open:DBPATH]) return; 

     [sqlite executeNonQuery:@"DROP TABLE yourtable"]; 
     [sqlite executeNonQuery:@"CREATE TABLE yourtable (record1 TEXT NOT NULL, 
                  record2 TEXT NOT NULL, 
                  record3 TEXT NOT NULL, 
                  record4 TEXT NOT NULL);"]; 

     NSArray *results = [sqlite executeQuery:@"SELECT * FROM yourtable;"]; 
     for (NSDictionary *dictionary in results) { 

      for (NSString *key in [dictionary keyEnumerator]) 
       NSLog(@" - %@ %@", key, [dictionary objectForKey:key]); 
     } 

     [results release]; 
     [sqlite release]; 
    } 
}