Sql>DECLARE
          String1 VARCHAR2(30):='Oracle';
          String2 VARCHAR2(30):='Corporation';
    BEGIN
          DBMS_OUTPUT.PUT_LINR('Your First String is :'||String1);
          DBMS_OUTPUT.PUT_LINR('Your Second String is:'||String2);
          DBMS_OUTPUT.PUT_LINR('Your Final String is :'||String1||String2);
    END;

STEPS TO COMPILE and PRODUCE OUTPUT:


a) At SQL PROMPT TYPE
     Sql> SET SERVEROUTPUT ON;
b) Place forward slash and press Enter Key.
     Sql>/
     Sql> DECLARE
               MyNumber1NUMBER:=10;
               MyNumber1NUMBER:=20;
          BEGIN
               DBMS_OUTPUT.PUTLINE('Your First Number is :'||MyNumber1);
               DBMS_OUTPUT.PUTLINE('Your First Number is :'||MyNumber2);
               DBMS_OUTPUT.PUTLINE('Your First Number is :'||MyNumber1'and'||MyNumber2||'is:'||To_Char(MyNumber1+MyNumber2,'999.99'));
          END;

    Sql>DECLARE
              V_FirstName              VARCHAR2(30):='&FName';
              V_MiddleName             VARCHAR2(30):='&MName';
              V_LastName               VARCHAR2(30):='&LName';
              V_DOB                    DATE:='&DateOfBirth';
        BEGIN
              DBMS_OUTPUT.PUTLINE('Your First Name is :'||V_FirstName);
              DBMS_OUTPUT.PUTLINE('Your Middle Name is:'||V_MiddleName);
              DBMS_OUTPUT.PUTLINE('Your Last Name is  :'||V_LastName);
              DBMS_OUTPUT.PUTLINE('******Concatenating*********');
              DBMS_OUTPUT.PUTLINE('Your Full Name is  :'||V_FirstName||' '||V_MiddleName||' '||V_LastName);
              DBMS_OUTPUT.PUTLINE('Your Date Of Birth is  :'||V_DOB);
              DBMS_OUTPUT.PUTLINE('Your Age is  :'||Trunc((SYSDATE-V_DOB)/365));
        END;
    Sql>DECLARE
              V_FirstNum NUMBER:=&FNumber;
              V_SecondNum NUMBER:=&SNumber;
              V_Result NUMBER:=0;
        BEGIN
              DBMS_OUTPUT.PUTLINE('You Gave me'||V_FirstNum||'and'||V_SecondNum);
              DBMS_OUTPUT.PUTLINE('I Excepted their Sum and The Result is:'||To_Char(V_FirstNum+V_SecondNum,'999.99'));
              DBMS_OUTPUT.PUTLINE('As You did not Relinitialize the Result variable it is having:'||V_Result||'only');
        END;