查詢語句不執行xcode中的sqlite數據庫

Question

我在我的項目中使用sqlite數據庫mathFActs，通過Sqlite數據庫瀏覽器創建它並將其添加到Xcode。以下是從一個視圖控制器類我的代碼

- (void)viewDidLoad 
{ [super viewDidLoad]; 

    [self copyDatabaseIfNeeded]; 
    [self getInitialDataToDisplay:[self getDBPath]]; 
} 


- (void) copyDatabaseIfNeeded { 
    //Using NSFileManager we can perform many file system operations. 
    NSFileManager *fileManager = [NSFileManager defaultManager]; 
    NSError *error; 

    NSString *dbPth = [self getDBPath]; 
    BOOL success = [fileManager fileExistsAtPath:dbPth]; 

    if(!success) { 

     NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"mathFActs"]; 
     success = [fileManager copyItemAtPath:defaultDBPath toPath:dbPath error:&error]; 

     if (!success) 
      NSAssert1(0, @"Failed to create writable database file with message '%@'.", [error localizedDescription]); 
    } 
} 
- (NSString *) getDBPath { 

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory , NSUserDomainMask, YES); 
    NSString *documentsDir = [paths objectAtIndex:0]; 
    return [documentsDir stringByAppendingPathComponent:@"mathFActs"]; 

} 

-(void) getInitialDataToDisplay:(NSString *)databasePath{ 

    if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) { 
     NSLog(@"open"); 
    const char *sql = "select Question from math "; 
     sqlite3_stmt *selectstmt; 
     if(sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL) == SQLITE_OK) { 
      NSLog(@"prepare"); 
      while(sqlite3_step(selectstmt) == SQLITE_ROW) { 

       NSString *addressField = [[NSString alloc] initWithUTF8String:(const char *) sqlite3_column_text(selectstmt, 0)]; 
       //address.text = addressField; 

       qstn.text=addressField;   
       sqlite3_finalize(selectstmt); 

      }} 
     else 
      sqlite3_close(database); //Even though the open call failed, close the database connection to release all the memory. 
    } 

} 

當我運行該項目，其打印開放，但不準備意味着它不執行查詢語句.. plz幫助我解決我的問題

Answer 1

試試這個： -

-(void) getInitialDataToDisplay:(NSString *)databasePath 
{ 
    if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) 
    { 
     NSLog(@"open"); 
     const char *sql = "select Question from math "; 
     sqlite3_stmt *selectstmt; 
     if(sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL) == SQLITE_OK) { 
      NSLog(@"prepare"); 
      while(sqlite3_step(selectstmt) == SQLITE_ROW) { 

       NSString *addressField = [[NSString alloc] initWithUTF8String:(const char *) sqlite3_column_text(selectstmt, 0)]; 
       //address.text = addressField; 

       qstn.text=addressField;   


      } 
      sqlite3_reset(selectstmt); 
     } 
     else 
     { 
      NSLog(@"Error: failed to select details with message '%s'.", sqlite3_errmsg(database)); 
     } 
     sqlite3_finalize(selectstmt); 
     sqlite3_close(database); //Even though the open call failed, close the database connection to release all the memory. 
    } 

} 

編輯： -

-(void)copyDatabaseIfNeeded 
{ 
    @try 
    { 
     NSFileManager *fmgr=[NSFileManager defaultManager]; 
     NSError *error; 
     NSArray *paths=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES); 
     NSString *path=[paths objectAtIndex:0]; 
     dbPath=[path stringByAppendingPathComponent:@"mathFActs.sqlite"]; 
     if(![fmgr fileExistsAtPath:dbPath]){ 
      NSString *defaultDBPath=[[[NSBundle mainBundle]resourcePath]stringByAppendingPathComponent:@"Addict.sqlite"]; 
      if(![fmgr copyItemAtPath:defaultDBPath toPath:dbPath error:&error]) 
       NSLog(@"failure message----%@",[error localizedDescription]); 
     } 

    } 
    @catch (NSException *exception) 
    { 
     NSLog(@"Exception: %@", exception); 
    } 

} 

-(NSString *)getDBPath 
{ 
    //Search for standard documents using NSSearchPathForDirectoriesInDomains 
    //First Param = Searching the documents directory 
    //Second Param = Searching the Users directory and not the System 
    //Expand any tildes and identify home directories. 
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory , NSUserDomainMask, YES); 
    NSString *documentsDir = [paths objectAtIndex:0]; 
    return [documentsDir stringByAppendingPathComponent:@"mathFActs.sqlite"]; 
} 

-(void)openDatabase 
{ 
    [self copyDatabaseIfNeeded]; 

    if (sqlite3_open([dbPath UTF8String], &database) == SQLITE_OK) 
    { 
     //Database Opened 
     NSLog(@"Database opened"); 
    } 
    else 
    { 
     NSLog(@"Database cannot be opened"); 
    } 
} 

-(void)closeDatabase 
{ 
    sqlite3_close(database); 
} 

希望它可以幫助你