Slide 9.3: Variables and types

Variables and Types

PL/SQL variable type can be one of the following three types:

One of the Types Used by SQL for Database Columns

A Generic Type Used in PL/SQL Such as NUMBER

The most commonly used generic type is NUMBER. Variables of type NUMBER can hold either an integer or a real number.
The most commonly used character string type is VARCHAR(n), where n is the maximum length of the string in bytes. This length is required, and there is no default. For example, we might declare:
```
   DECLARE
     price   NUMBER;
     myBeer  VARCHAR(20);
```
Note that PL/SQL allows BOOLEAN variables, even though Oracle does not support BOOLEAN as a type for database columns.

Declared to Be the Same as the Type of some Database Column

In many cases, a PL/SQL variable will be used to manipulate data stored in an existing relation. For example,
```
   DECLARE
     myBeer  Beers.name%TYPE;
```
gives PL/SQL variable myBeer whatever type was declared for the name column in relation Beers.

A variable may have a type that is a record with several fields; e.g., assume that the relation has the schema Beers(name, manufacture).
```
   DECLARE
     beerTuple  Beers%ROWTYPE;
```
makes variable beerTuple be a record with fields name & manufacture.