Oracle SQL Developer

Utilizing the Main Features of PL/SQL■■■■■■■■■■■■■■Declaring Variables and ConstantsUsing Identifiers in PL/SQLAssigning Values to a Variable With the Assignment OperatorUsing LiteralsDeclaring and Assigning Variables With DEFAULT or NOT NULLAssigning Values to a Variable With SELECT INTOInputting and Outputting Data with PL/SQLUsing %ROWTYPE and %TYPE Attributes to Declare Data TypesUsing PL/SQL Control StructuresUsing Local PL/SQL Subprograms in PL/SQL BlocksWorking With PL/SQL Data StructuresProcessing Queries with PL/SQLUsing Dynamic SQL in PL/SQLUsing Bind Variables7.3.1 Using PL/SQL Block StructureAs Example 7–1 shows, a PL/SQL block has three basic parts: a declarative part(DECLARE), an executable part (BEGIN .. END), and an exception-handling(EXCEPTION) part that handles error conditions. For a discussion of exceptionhandling, see "Handling PL/SQL Errors" on page 7-21.Only the executable part is required. The optional declarative part is written first,where you define types, variables, and similar items. These items are manipulated inthe executable part. Exceptions raised during execution can be dealt with in theexception-handling part.Note the comments that are added to the PL/SQL code. See "Using Comments" onpage 7-4. Also, not the use of DBMS_OUTPUT.PUT_LINE to display output. See"Inputting and Outputting Data with PL/SQL" on page 7-9.Example 7–1Simple PL/SQL Block-- the following is an optional declarative partDECLAREmonthly_salaryNUMBER(6);number_of_days_worked NUMBER(2);pay_per_dayNUMBER(6,2);-- the following is the executable part, from BEGIN to ENDBEGINmonthly_salary := 2290;number_of_days_worked := 21;pay_per_day := monthly_salary/number_of_days_worked;-- the following displays output from the PL/SQL blockDBMS_OUTPUT.PUT_LINE('The pay per day is ' || TO_CHAR(pay_per_day));-- the following is an optional exception part that handles errorsEXCEPTIONWHEN ZERO_DIVIDE THENpay_per_day := 0;PL/SQL: Usage Information 7-3