Understanding SQR Data Elements
!Variables
!Variables are storage places for text or numbers that you define and manipulate.
!• $ begins a text or date variable.
!• # begins a numeric variable.
!• % begins a list variable.
!• @ begins a variable name for a marker location.
!Columns
!Columns are fields defined in the database.
!SQR FOR P EOPLE S OFT L ANGUAGE REFERENCE
!The character & begins a database column or expression name.
!Literals
!Literals are text or numeric constants.
!• A single quote begins and ends a text literal. For example:
!‘Hello‘
!• Numerals 0–9 begin numeric literals.
!Numerals that include digits with an optional decimal point and leading sign are acceptable
!numeric literals. For example, –543.21. Numeric literals can also be expressed in scientific
!form. For example, 1.2E5.
原文：http://www.cnblogs.com/binquan/p/SQR.html