3.22 Learning to understand HttpContext and where 1=1

1, HttpContext
HttpContext.Current.Session.RemoveAll (); Removes all keys and values from the session-state collection. (not expired, still exists)
HttpContext.Current.Session.Abandon ();? Clears all current session (expired)
2, where 1 = 1
The condition after 1=1 in the where condition is changed dynamically through the If block. For example:
String sql= "SELECT * FROM table_name where 1=1";
if (Conditon1)
{
sql=sql+ "Andvar2=value2";
}
if (Conditon2)
{
sql=sql+ "Andvar3=value3";
}
Where 1=1 is to avoid a syntax error because the first word that follows the WHERE keyword is directly "and". 1=1 conditions, typically used to construct dynamic SQL statements, "SELECT ... From ... WHERE 1=1 "+ dynamic construction condition clause.

3.22 Learning to understand HttpContext and where 1=1