Operators and functions let you calculate results derived from column values, system-determined values, constants, and other data. 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 ...