Sqlite3_step（）在這個查詢中繼續返回SQLITE_MISUSE。任何指針？

Question

我想在viewDidLoad例程中打開一個sqlite數據庫，並試圖發送一個sql查詢到數據庫，但sqlite_step（）每次都失敗。我不確定這裏有什麼問題。我只是試圖在sqlite3上作爲hello world的嘗試。

#import "RootViewController.h" 
#import "sqlite3.h" 

static sqlite3_stmt *statement = nil; 

@implementation RootViewController 

- (void)viewDidLoad { 
    [super viewDidLoad]; 
    NSString *dbname = @"name.sqlite"; 
    sqlite3 *database; 
    int success; 

    // Uncomment the following line to display an Edit button in the navigation bar for this view controller. 
    // self.navigationItem.rightBarButtonItem = self.editButtonItem; 
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsDirectory = [paths objectAtIndex:0]; 
    NSString *path = [documentsDirectory stringByAppendingPathComponent:dbname]; 
    // Open the database. The database was prepared outside the application. 
    success = sqlite3_open([path UTF8String], &database); 
    if (success == SQLITE_OK) { 
     NSLog(@"database opening successful : %d", success); 
    } else { 
     // Even though the open failed, call close to properly clean up resources. 
     sqlite3_close(database); 
     NSLog(@"database opening failed : %d", success); 
     // Additional error handling, as appropriate... 
    } 
    if (statement == nil) { 
     const char *sql = "insert into name(nid, name) values(6, 'testname');"; 
     success = sqlite3_prepare_v2(database, sql, -1, &statement, NULL); 
     NSLog(@"query prepare status: %d", success); 
     if (success != SQLITE_OK) { 
     } 
    } 

    success = sqlite3_step(statement); //things fail here, as all calls above return ok 
    NSLog(@"query step status: %d", success); 
    if (success != SQLITE_DONE) { 
    } 
    sqlite3_reset(statement); 
    sqlite3_close(database); 
} 
... 

如果有人能指出我哪裏可能會出錯，那將是一件好事。感謝您的時間已經。

Answer 1

您是否驗證過該語句編譯成功？您有success = sqlite3_prepare_v2(...);一行，但如果success不是SQLITE_OK，則不會執行任何操作。你確認它是SQLITE_OK？

在另一方面，如果你使用的包裝像FMDB，你可以取代所有的代碼上面：

- (void)viewDidLoad { 
    [super viewDidLoad]; 
    NSString *dbname = @"name.sqlite"; 
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsDirectory = [paths objectAtIndex:0]; 
    NSString *path = [documentsDirectory stringByAppendingPathComponent:dbname]; 
    FMDatabase * database = [FMDatabase databaseWithPath:path]; 

    [database executeUpdate:@"insert into name(nid, name) values(?, ?)", [NSNumber numberWithInt:6], @"testname"]; 
    [database close]; 
} 

此，國際海事組織，是多更容易調試。

Answer 2

我做到了這一點，但它仍然無法正常工作，因爲在控制檯中什麼也沒有顯示。

 
#import "RootViewController.h" 
#import "FMDatabase.h" 

@implementation RootViewController 

- (void)viewDidLoad { 
    [super viewDidLoad]; 
    NSString *dbname = @"name.sqlite"; 
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsDirectory = [paths objectAtIndex:0]; 
    NSString *path = [documentsDirectory stringByAppendingPathComponent:dbname]; 
    FMDatabase * database = [FMDatabase databaseWithPath:path]; 
    FMResultSet *rs = [database executeQuery:@"select * from name;"]; 
    while ([rs next]) { 
     NSLog(@"%d %@", 
       [rs intForColumn:@"nid"], 
       [rs stringForColumn:@"name"]); 
    } 
    [database close]; 
} 
... 

對不起，但無法使用代碼塊，所以再次使用pre。

編輯：當我打開在FMDB登錄，就像這樣：

 
    FMDatabase * database = [FMDatabase databaseWithPath:path]; 

    [database setLogsErrors:YES]; 

    if (![database open]) { 
     NSLog(@"Could not open db."); 
    } else { 
     NSLog(@"DB Open...."); 
    } 
    FMResultSet *rs = [database executeQuery:@"select * from 'name';"]; 
    while ([rs next]) { 
     // just print out what we've got in a number of formats. 
     NSLog(@"%d %@", 
       [rs intForColumn:@"nid"], 
       [rs stringForColumn:@"name"]); 
    } 
    [database close]; 

...，我得到這個在控制檯：

 
[Session started at 2010-09-07 15:38:16 +0530.] 
2010-09-07 15:38:19.178 MyDBTry[13670:207] DB Open.... 
2010-09-07 15:38:19.181 MyDBTry[13670:207] DB Error: 1 "no such table: name" 
2010-09-07 15:38:19.182 MyDBTry[13670:207] DB Query: select * from name;