Oracle PL/SQL Programming: A Developer's Workbook

Chapter 1. Declaring Variables and Naming Elements

Variables allow you to store and manipulate data—such as column values, counters, or calculations—inside your PL/SQL programs. There are two types of variables: scalar, which are made up of a single value, and composite, which are made up of multiple pieces (a record, for example, is represented with a composite variable). Whether composite or scalar, every variable has a name (also called an identifier), a datatype (such as NUMBER or VARCHAR2), and a value. This chapter tests your ability to work with these most basic PL/SQL elements.

Beginner

1-1.	Which of the following identifiers are valid, which are invalid, and why? my_variable2 my-variable2 my^variable MyVariable my_variable_for_many_many_of_usages 123myvariable “123myvariable”
1-2.	Which of the following blocks will compile, and which will fail to compile? Why? DECLARE lastdate DATE; lastDate NUMBER; BEGIN NULL; END; DECLARE lastdate DATE := sysdate; lastDate NUMBER := 50; BEGIN dbms_output.put_line(lastdate); dbms_output.put_line(lastDate); END;
1-3.	Declare a date variable with an initial value of SYSDATE (show both valid formats).
1-4.	Declare a local variable to have the same datatype as the last_name column in the employee table.
1-5.	Explain what is wrong with each of the following declarations: DECLARE INTEGER year_count; VARCHAR2(100) company_name, employee_name; delimiters VARCHAR2; curr_year CONSTANT INTEGER; invalid_date EXCEPTION := VALUE_ERROR;
1-6.	What datatype is most appropriate ...