OleDb参数阵列格式

Question

嗨，在OleDB文档中（链接在下面），他们有一个参数叫做 OleDbParameter[] parameters在一个函数中，一个循环然后在该数组上迭代，将参数插入到SQL中。

我在文档中找不到你应该如何格式化那个数组？

文档中。https:/docs.microsoft.comen-usdotnetapisystem.data.ledb.ledbcommand.parameters?view=dotnet-plat-ext-3.1。

Answer 1

Microsoft Example中的代码是错误的，不能编译。我已经发了一个反馈。这里有一个更正确的版本，有关于修改的注释。

public void CreateMyOleDbCommand(OleDbConnection connection,
                  string queryString, OleDbParameter[] parameters)
{
    OleDbCommand command = new OleDbCommand(queryString, connection);

    // This destroys the commandtext set by querystring in the constructor.
    // command.CommandText =
    //    "SELECT CustomerID, CompanyName FROM Customers WHERE Country = ? AND City = ?";

    // This cannot work, you can't add an array with Add but only one element
    // command.Parameters.Add(parameters);
    command.Parameters.AddRange(parameters);

    // After AddRange this loop is pointless and creates possible errors with
    // too many parameters added to the collection
    // for (int j=0; j<parameters.Length; j++)
    //{
    //    command.Parameters.Add(parameters[j]) ;
    //}

    string message = "";
    for (int i = 0; i < command.Parameters.Count; i++)
    {
        message += command.Parameters[i].ToString() + "\n";
    }
    Console.WriteLine(message);
}

现在要调用这个函数，你必须

string cmdText = @"SELECT CustomerID, CompanyName 
                   FROM Customers 
                   WHERE Country = ? AND City = ?";
OleDbParameter[] parameters = new OleDbParameter[]
{
    new OleDbParameter{ ParameterName = "?",OleDbType = OleDbType.VarWChar, Value = "UK" },
    new OleDbParameter{ ParameterName = "?",OleDbType = OleDbType.VarWChar, Value = "London"},
};
CreateMyOleDbCommand(myConnection, cmdText, parameters);