iOS的SQLite的Blob數據保存NULL

Question

我想插入一個使用此代碼的SignatureView的BLOB數據，但是當我實際瀏覽數據庫時有空而不是數據。 我的簽名表模式如下。

create table sign（id integer primary key AUTOINCREMENT，image blob，invoiceid integer）;

-(void)storeImageData:(NSData *)imageData withInvoiceID:(NSInteger)invoiceID{ 

    NSString *dbPath = [[[NSBundle mainBundle] resourcePath ]stringByAppendingPathComponent:@"database.sqlite3"]; 
    const char *dbpath = [dbPath UTF8String]; 
    sqlite3 *contactDB; 

    sqlite3_stmt *statement; 

    NSLog(@"%@",dbPath); 
    if (sqlite3_open(dbpath, &contactDB) == SQLITE_OK) 
    { 
     int invoiceIDINT = (int)invoiceID; 
    // 
     NSString *insertSQL = [NSString stringWithFormat: @"INSERT INTO sign (image,invoiceid) VALUES (?,%d)", invoiceIDINT]; 

     const char *insert_stmt = [insertSQL UTF8String]; 

     sqlite3_prepare_v2(contactDB, insert_stmt, -1, &statement, NULL); 
     if (sqlite3_step(statement) == SQLITE_DONE) 
     { 
      sqlite3_bind_blob(statement, 2, [imageData bytes], [imageData length], SQLITE_TRANSIENT); 
      sqlite3_step(statement); 

     } else { 
      const char *Error = sqlite3_errmsg(database); 
      NSString *error = [[NSString alloc]initWithUTF8String:Error]; 
      UIAlertView *view = [[UIAlertView alloc]initWithTitle:@"Error2" message:[NSString stringWithFormat:@"Last inserted ID: %@",error] delegate:nil cancelButtonTitle:@"Cancel" otherButtonTitles:nil, nil]; 
      [view show]; 
     } 
     sqlite3_finalize(statement); 
     sqlite3_close(contactDB); 
    } 


} 

Answer 1

1. 經常檢查sqlite3_prepare_v2結果。如果失敗，請使用sqlite3_errmsg記錄問題。
2. 如果sqlite3_prepare_v2成功，請致電sqlite3_finalize。
3. 由於您撥打sqlite3_bind_blob傳遞了錯誤的列索引，因此您獲得了NULL的blob。它應該是1，而不是2，因爲您想綁定到INSERT語句中的第一個?。
4. 爲什麼不一致？爲什麼使用stringWithFormat來設置invoiceid列的值，然後在image列中使用sqlite_bind_xxx？你應該綁定兩者。切勿使用stringWithFormat來構建查詢。
5. 您撥打sqlite3_step兩次。在你打電話之前，只調用一次並綁定你的值。
6. 您似乎正在寫入應用程序資源包內的數據庫。你不能在真實的設備上做到這一點。它在模擬器中工作，但不在真實的iOS設備上。您需要將數據庫文件放入「文檔」文件夾中。

鑑於上述所有的，你的代碼應該是這樣的：

-(void)storeImageData:(NSData *)imageData withInvoiceID:(NSInteger)invoiceID{ 
    // This is wrong - you need to update this to use the Documents folder 
    NSString *dbPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"database.sqlite3"]; 
    const char *dbpath = [dbPath UTF8String]; 
    NSLog(@"%@",dbPath); 

    sqlite3 *contactDB; 
    if (sqlite3_open(dbpath, &contactDB) == SQLITE_OK) 
    { 
     const char *insert_stmt = "INSERT INTO sign (image, invoiceid) VALUES (?, ?)"; 

     sqlite3_stmt *statement; 
     if (sqlite3_prepare_v2(contactDB, insert_stmt, -1, &statement, NULL) == SQLITE_OK) { 
      sqlite3_bind_blob(statement, 1, [imageData bytes], [imageData length], SQLITE_TRANSIENT); 
      sqlite3_bind_int(statement, 2, (int)invoiceID); 

      if (sqlite3_step(statement) == SQLITE_DONE) { 
       // Row inserted successfully 
      } else { 
       const char *Error = sqlite3_errmsg(contactDB); 
       NSString *error = [[NSString alloc] initWithUTF8String:Error]; 
       UIAlertView *view = [[UIAlertView alloc] initWithTitle:@"Error2" message:[NSString stringWithFormat:@"Last inserted ID: %@",error] delegate:nil cancelButtonTitle:@"Cancel" otherButtonTitles:nil, nil]; 
       [view show]; 
      } 

      sqlite3_finalize(statement); 
     } else { 
      NSLog(@"Unable to prepare statement %s: %s", insert_stmt, sqlite3_errmsg(contactDB)); 
     } 

     sqlite3_close(contactDB); 
    } else { 
     NSLog(@"Unable to open database at path %@: %s", dbPath, sqlite3_errmsg(contactDB)); 
    } 
}