Operators and functions permit you to calculate results derived from column data, system-determined values, and constant expressions. You can perform:
Arithmetic operations— Cut everyone’s salary by 10 percent.
String operations— Concatenate personal information into a mailing address.
Datetime operations— Compute the time interval between two dates.
System operations— Find out what time your DBMS thinks it is.
An operator is a symbol or keyword indicating an operation that acts on one or more elements. The elements, called operands, are SQL expressions. Recall from the “SQL Syntax” Tips in Chapter 3 that an expression is any legal combination of symbols and tokens that evaluates to a single value (or null). In ...