Question

Here’s my code. I am not able to set TableName variable, it is throwing an exception
Must declare the table variable “@TableName”

public DataTable getAllDataFromTable(String TableName)
        {

            cmd.CommandText = "select * from @TableName";
            cmd.Parameters.AddWithValue("@TableName", TableName);
            da.SelectCommand = cmd;
            da.Fill(dt);
            return dt;

        }

Answer 1

You cannot use a parameter in that fashion. The best way to implement what you are looking for is to use a string.Format() method to create your select statement. The only real draw back is the fact you open the method up to SQL Injection.

public DataTable getAllDataFromTable(String TableName)
{

        cmd.CommandText = string.Format("select * from {0}", TableName)";
        da.SelectCommand = cmd;
        da.Fill(dt);
        return dt;

    }

Here is a similar thread.

Table name and table field on SqlParameter C#?