Question

我正在做一个从Web服务获取JSON数据并在SQLite数据库中更新它的应用程序。我的问题是我从Web服务获得了值，但在上传时显示'null'。它没有得到更新。

我的代码： -

-(void) updateSignupTable: (NSDictionary*) json {
    //copying the values from web services

    NSString *balance =  [json objectForKey:@"balance"];
    NSString *phone_number =[json objectForKey:@"sim_number"];
    NSString *call_forward_Status = [json objectForKey:@"call_forward_status"];

//将其存储在数据库中

    sqlExecutObj.sql=[NSString stringWithFormat:@"UPDATE profile_table SET phone_number ='%@' balance = '%@' call_forward_status = '%@' WHERE profile_name= '%@'", phone_number ,balance, call_forward_Status, profileDetailTitle];

    sqlExecutObj.dataTypeArray=[[NSMutableArray alloc]initWithObjects:@"1",@"1",@"1",nil];

    [sqlExecutObj executeSelectQuery];
///reloading the table    
    [profileDetailView.detailsTableView reloadData];

    // fetch and print the  updated datas from SQLite

    sqlExecutObj.sql=[NSString stringWithFormat:@"SELECT call_forward_status,phone_number,balance FROM profile_table WHERE profile_name= '%@'",selectedProfileName];

    sqlExecutObj.dataTypeArray=[[NSMutableArray alloc]initWithObjects:@"1",@"1",@"1",nil];

    [sqlExecutObj executeSelectQuery];

    NSLog(@"result from table are: %@. and  %@, and %@", [[sqlExecutObj.result objectAtIndex:0] objectAtIndex:0],[[sqlExecutObj.result objectAtIndex:1] objectAtIndex:0],[[sqlExecutObj.result objectAtIndex:2]objectAtIndex:0] );
}

我的调试输出： -

2013-05-14 15:54:02.910 Movirtu[44262:19d03] result from table are: (null). and  (null), and (null)

Answer 1

要谨慎，请注意以下几行：

 sqlExecutObj.sql=[NSString stringWithFormat:@"UPDATE profile_table SET phone_number ='%@' balance = '%@' call_forward_status = '%@' WHERE profile_name= '%@'", phone_number ,balance, call_forward_Status, profileDetailTitle];

将profileDetailTitle指定为profile_name，但是第二个语句指定您从数据库中读取数据：

sqlExecutObj.sql=[NSString stringWithFormat:@"SELECT call_forward_status,phone_number,balance FROM profile_table WHERE profile_name= '%@'",selectedProfileName];

指定profile_name是'selectedProfileName'。

在您的代码中，profileDetailTitle或selectedProfileName是什么并不明显。也许为了调试，您可以将它们设置为相同的值。

另外，为了确保，如果profileDetailTitle或selectedProfileName是用户驱动的，或者只是包含非字母数字字符，您应该（绑定），健全性检查，转义这些值。对于输入到数据库中的任何其他值也是如此 - 但这不是范围; - ）

Sqlite数据库不会更新Web服务中的数据

1 个答案: