Sams Teach Yourself SQL in 10 Minutes, Second Edition

Using Functions

Most SQL implementations support the following types of functions:

• Text functions are used to manipulate strings of text (for example, trimming or padding values and converting values to upper and lowercase).

• Numeric functions are used to perform mathematical operations on numeric data (for example, returning absolute numbers and performing algebraic calculations).

• Date and time functions are used to manipulate date and time values and to extract specific components from these values (for example, returning differences between dates, and checking date validity).

• System functions return information specific to the DBMS being used (for example, returning user login information).

In the last lesson, you saw a function used as part of ...