Question

我正在尝试创建一个语句来检查来自foxpro数据库的数据对c＃

中的字符串

然而，我似乎无法让它工作，在这里使用参数化查询有助于实现我正在尝试做的事情？

string PROPCODE = "IMPORT_" + ID;
string leadtenant = clcodet;
using (OleDbCommand tenantpopulation = new OleDbCommand(@"SELECT 
    CLCODE, 
    CLCODEDESC 
    FROM CLIENT WHERE PROPCODET = " + PROPCODE, importConnection))
{
    string tenants = "";
    if (@"CLCODE" = leadtenant)
    {
        if (tenants != String.Empty)
        {
            //do something
        }
    }
}

要澄清，我想检查从租户人口调用的CLCODE是否匹配代码中其他地方定义的leadtenant

Answer 1

其他人已经注意到使用参数是要走的路（不仅在VFP中，而且在任何SQL数据库中）。它们不仅用于防止SQL注入攻击，还使用驱动程序负责转换为正确字符串的参数，添加/删除括号，引号等。

string PROPCODE = "IMPORT_" + ID;
string leadtenant = clcodet;

using (OleDbCommand tenantpopulation = new OleDbCommand(@"SELECT
CLCODE
FROM CLIENT WHERE PROPCODET = ?", importConnection))
{
    tenantpopulation.Parameters.AddWithValue("p", PROPCODE);

    // rest of code seem to be meaningless
    // and I didn't see any code where you run your query
    // depending on your requirement, I assume PROPCODET is a primary key?
    // if so then you to do the check you only need to return the CLCODE
    // with ExecuteScalar:

    importConnection.Open();
    var clcode = (string)tenantpopulation.ExecuteScalar();
    importConnection.Close();       

    string tenants = "";

    // in C# equality check is done with == NOT = (assingment)
    if (clcode == leadtenant)
    {
        // tenants is always String.Empty here
        if (tenants != String.Empty)
        {
            //do something
        }
    }
}

PS：你有没有想过，使用来自codeplex的Tom Brother的LinqToVFP？使用Linq，您不需要太多地了解这些SQL方言，而是使用对象查询（和智能感知）。

如何将select语句中的记录与c＃中的字符串进行匹配？

1 个答案: