是否可以在不求助于动态 SQL 的情况下查询用户指定的列名? [英] Is it possible to query a user-specified column name without resorting to dynamic SQL?

问题描述

我正在尝试实现具有以下签名的 API:

I am trying to implement an API with the following signature:

public static List<string> SearchDatabase(
    string column,
    string value);

API 的实现需要构造一个带有 WHERE 子句的 SQL SELECT 查询，该子句使用在 column 参数中指定的列名.

The implementation of the API needs to construct an SQL SELECT query with a WHERE clause that uses a column name specified in the column parameter.

查询:

string query =
    string.Format(
        "SELECT Name, @Column " +
        "FROM Db1 " +
        "INNER JOIN Db2 ON Db1.Id = Db2.Id " +
        "WHERE @Column = @Value");

SQL 命令和参数:

SqlCommand selectCmd =
    new SqlCommand(
        query,
        connection);
selectCmd.CommandTimeout = SqlCommandTimeout;
selectCmd.Parameters.AddRange(
    new SqlParameter[]
{
    new SqlParameter("@Column", column),
    new SqlParameter("@Value", value)
});

我是这样执行的:

SqlDataReader sqlDataReader = selectCmd.ExecuteReader();
while (sqlDataReader.Read())
{
    // ...
}

问题是 sqlDataReader 不返回任何行，所以我没有进入上面的 while 循环.

The problem is that sqlDataReader doesn't return any rows, so I don't go into the while loop above.

但是，如果我将上面查询的最后一行从:

However, if I change the last line of the query above from:

"WHERE @Column = @Value");

到

"WHERE Vendor = @Value");

(即，将列名硬编码为供应商")然后它就可以工作了.

(i.e. hardcode the column name to 'Vendor') then it works.

我从我所做的研究中了解到，不能将列名作为参数传递，而只能传递我们正在查询的值.但是，它似乎让我在 SELECT 子句中使用 @Column 参数，而不是 WHERE 子句.

My understanding from research I have done is that it's not possible to pass column names as parameters, but only values we are querying on. But, it does appear to let me use the @Column parameter in the SELECT clause, just not the WHERE clause.

由于 SQL 注入的问题，我不想求助于动态 SQL.有没有其他办法解决这个问题?

I don't want to resort to dynamic SQL because of the issues with SQL injection. Is there another way around this?

推荐答案

遗憾的是表名、列名不能参数化.因为你知道表的结构，所以你可以在这个参数中有一个可能的列名的白名单，然后使用字符串连接来避免 SQL 注入:

Unfortunately table names, column names cannot be parametrized. Because you know the structure of the table you could have a whitelist of possible column names in this parameter and then use string concatenation for it to avoid SQL injection:

"WHERE " + Sanitize(column) + " = @Value");

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