如何比较两个查询的结果？

Question

I'd like to compare two query results to see if they are the same or not. If the result is the same, I want to display a MessageBox ; if not do something else.

using (OracleCommand crtCommand = new OracleCommand(query1, conn1))
{
    string result1 = crtCommand.ExecuteScalar().ToString();
}

using (OracleCommand ctCommand = new OracleCommand("query2", conn1))
{
    string result2 = ctCommand.ExecuteScalar().ToString();
}

if (result1 == result2)
    MessageBox.Show("They are same");
else
    MessageBox.Show("They are not same");

Answer 1

您需要在using语句之外声明变量，以便它们在该范围之外可见。

Answer 2

If both your queries return string output you can use string.Compare method to compare them and conditionally do what you want to do, base on output. However, it can't be that simple what you are asking. Can you elaborate further your question?

Answer 3

All you need to do is declare the strings outside of the using blocks but still assign them inside the using blocks.

string result1;
string result2;

using (OracleCommand crtCommand = new OracleCommand(query1, conn1))
{
    result1 = crtCommand.ExecuteScalar().ToString();
}

using (OracleCommand ctCommand = new OracleCommand("query2", conn1))
{
    result2 = ctCommand.ExecuteScalar().ToString();
}

if (result1.Equals(result2))
    MessageBox.Show("They are same");
else
    MessageBox.Show("They are not same");

Also I recommend replacing your == with .Equals() , if you want you can set options to make it case insensitive too so THIS and this are considered equal

if (result1.Equals(result2, StringComparison.OrdinalIgnoreCase))
    MessageBox.Show("They are same");
else
    MessageBox.Show("They are not same");