Please guide, simple database statements

Please point, simple database statement
$query = "SELECT OrderID from Orders where
CustomerID = $customerid and
Amount > ". $_session[' Total_price ']." -.001 and//What do you mean by this sentence? " What do you mean,-.001?
Amount < ". $_session[' Total_price ']." +.001 and//What do you mean by this sentence? " What do you mean, +.002?
Date = ' $date ' and
Order_status = ' PARTIAL ' and
Ship_name = ' $ship _name ' and
ship_address = ' $ship _address ' and
ship_city = ' $ship _city ' and
Ship_state = ' $ship _state ' and
Ship_zip = ' $ship _zip ' and
Ship_country = ' $ship _country ' ";
------Solution--------------------
-0.001
+0.001
------Solution--------------------
Total_price value up and down floating 0.001 rice bowls inside

For example
Total_price = 1.001
Value 1.000 to 1.002
------Solution--------------------
is 0.001 and +0.001 of the arithmetic operations.

For example, the value of $_session[' Total_price '] is 1

Then the statement is equivalent to

$query = "SELECT OrderID from Orders where
CustomerID = $customerid and
Amount >0.999 and
Amount < 1.001 and
Date = ' $date ' and
Order_status = ' PARTIAL ' and
Ship_name = ' $ship _name ' and
ship_address = ' $ship _address ' and
ship_city = ' $ship _city ' and
Ship_state = ' $ship _state ' and
Ship_zip = ' $ship _zip ' and
Ship_country = ' $ship _country ' ";

