C# combobox value to pass to SQL parameter

问题

This question is related to my previous one here:

Populating C# combobox from SQL and restrict results based on choice

hoping to get more attention. Given a combobox from which I'd like to pass the value. On the SelectedIndexChange property I put a method, which calls a Stored Procedure from SQL.

SqlCommand command;

command.Parameters.Add("@someparameter", combobox1.GetItemText(combobox1.SelectedItem));

command.CommandText = "StoredProcedure1";

command.ExecuteNonQuery();

Well, it takes no effect. Anyone to point out what I'm doing wrong/missing? Thank you

回答1:

You have an SQL command and a parameter. You execute the command, but into what connection?

It's like me starting my engine, but I haven't actually got the rest of the car to drive. I can turn it on, but without a car I can't drive.

You can fix this by doing something like this:

SqlCommand newCmd = new SqlCommand("SELECT @someParameter from DATABASE", conn);

Notice the , conn at the end of the above command. This allows you to use a method such as ExecuteNonQuery(), and the command knows which connection to use for its query.

来源：https://stackoverflow.com/questions/40769430/c-sharp-combobox-value-to-pass-to-sql-parameter