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?
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1-2. | Which of the following blocks will compile, and which will fail to compile? Why?
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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 ... |