iphone - 在sqlite select语句中感到困惑

Question

我正在尝试从我的数据库中获取数据，但我没有得到解决我这样试试

-(无效)信息

{
    //[self createEditableCopyOfDatabaseIfNeeded];
    NSString *filePath = [self getWritableDBPath];

    sqlite3 *database;
    if(sqlite3_open([filePath UTF8String], &database) == SQLITE_OK)
    {
        NSString *qu = @"Select  Name FROM empl where SyncStatus ='1'";
        sqlite3_stmt *compiledStatement;
        if(sqlite3_prepare_v2(database, [qu UTF8String], -1, &compiledStatement, NULL) == SQLITE_OK) 
        {
            char *firstColumn = (char *)sqlite3_column_text(compiledStatement, 0);

            if (firstColumn==nil)
            {
                NSString *name= [[NSString stringWithUTF8String:firstColumn]autorelease];
                NSLog(@"%c",name);

            }
            if(sqlite3_step(compiledStatement) != SQLITE_ROW ) 
            {

                UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"UIAlertView" message:@"User is not valid" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
                [alert show];
                [alert release];
                alert = nil;
            }
        }
        sqlite3_finalize(compiledStatement);
    }
    sqlite3_close(database);
}

它崩溃了它向我显示错误原因:'* +[NSString stringWithUTF8String:]: NULL cString'* 第一次抛出调用堆栈:

Answer 1

像这样使用

if(sqlite3_step(compiledStatement) == SQLITE_ROW ) 
            {
                char *firstColumn = (char *)sqlite3_column_text(compiledStatement, 0);
                NSString *name= [[NSString alloc]initWithUTF8String:firstColumn];


            }

希望对你有所帮助