Oracle SQL Developer

Utilizing the Main Features of PL/SQLthe constant are allowed. For an example, see avg_days_worked_month inExample 7–3.For example, assume that you want to declare variables for employee data, such asemployee_id to hold 6-digit numbers and active_employee to hold the Booleanvalue TRUE or FALSE. You declare these and related employee variables and constantsas shown in Example 7–3.Note that there is a semi-colon (;) at the end of each line in the declaration section.Also, note the use of the NULL statement which enables you to execute and test thePL/SQL block.You can choose any naming convention for variables that is appropriate for yourapplication. For example, you could begin each variable name with the v_ prefix toemphasize that these are variable names.Example 7–3 Declaring Variables in PL/SQLDECLARE -- declare the variables in this sectionlast_nameVARCHAR2(30);first_nameVARCHAR2(25);employee_idNUMBER(6);active_employee BOOLEAN;monthly_salaryNUMBER(6);number_of_days_worked NUMBER(2);pay_per_dayNUMBER(6,2);avg_days_worked_month CONSTANT NUMBER(2) := 21; -- a constant variableBEGINNULL; -- NULL statement does nothing, allows this block to executed and testedEND;/7.3.4 Using Identifiers in PL/SQLSee Also: PL/SQL User's Guide and Reference for information on datatypes used with PL/SQL, including the PL/SQL BOOLEAN and PLS_INTEGER data typesYou use identifiers to name PL/SQL program items and units, such as constants,variables, exceptions, and subprograms. An identifier consists of a letter optionallyfollowed by more letters, numerals, dollar signs, underscores, and number signs.The declaration section in Example 7–4 illustrates some valid identifiers. You can seeadditional examples of valid identifiers for variable names in Example 7–2 on page 7-4and Example 7–3 on page 7-5.Example 7–4Valid Identifiers for VariablesDECLARE -- all declarations use valid identifiersxNUMBER;t2NUMBER;phone#VARCHAR2(12);credit_limit NUMBER;oracle$number NUMBER;money$$$tree NUMBER;SN##VARCHAR2(9);try_againBOOLEAN;BEGINNULL;END;/PL/SQL: Usage Information 7-5