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Oracle PL/SQL Programming: A Developer's Workbook
book

Oracle PL/SQL Programming: A Developer's Workbook

by Steven Feuerstein, Andrew Odewahn
May 2000
Intermediate to advanced content levelIntermediate to advanced
594 pages
11h 32m
English
O'Reilly Media, Inc.
Content preview from 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?

  1. my_variable2

  2. my-variable2

  3. my^variable

  4. MyVariable

  5. my_variable_for_many_many_of_usages

  6. 123myvariable

  7. “123myvariable”

1-2.

Which of the following blocks will compile, and which will fail to compile? Why?

  1. DECLARE
       lastdate DATE;
       lastDate NUMBER;
    BEGIN
       NULL;
    END;
  2. 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 ...

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Publisher Resources

ISBN: 9781449324070Supplemental ContentErrata Page