PL/SQL Basic case

Case study 1

problem ： 1. Count the number of employees employed each year

Their thinking ：

Cycle through the number of employees , Take out the entry date of each employee , Compliant , Counter plus 1

Code ：

set severoutput on

declare 
  --  Define cursor 
  cursor cemp is select to_char(hiredate,'yyyy') from emp;
  phiredate varchar2(4);
  
  -- Number of employees hired each year 
  count80 number :=0;
  count81 number :=0;
  count82 number :=0;
  count87 numner :=0;
  
  begin
  --  Open the cursor 
  open cemp;
  
  loop
  -- Take out the year of employment of an employee 
  fetch cemp into phiredate;
  exit when cemp%notfund;
  
  -- Determine the year of employment 
  if phiredate = '1980' then count80 :=count80+1;
  elsif phiredate ='1981' then count81 :=count81+1;
  elseif phiredate ='1982' then count82 :=count82+1;
  else count87 := count87+1;
  
  end loop;
  
  -- Close the cursor 
  close cemp;
  end;
  /

Case study 2

problem :2 Raise wages for employees . From the minimum wage rise, everyone grows 10%, But the total salary should not exceed 5 Ten thousand yuan , Please calculate the number of people who get a raise and the total salary after the raise , And output the number of wage increases and total wages .

Their thinking ：

Code ：

set serveroutput on

declare
--  Define cursor 
   cursor cemp is select empno,sal from emp order by sal;
   pempno emp.empno%type;
   psal emp.sal%type;
 
 -- The number of people who get a raise 
  countEmp number := 0;
  
  -- The total salary after the increase 
  salTotal number;
begin
   -- Get the initialization value of the total salary 
   select sum(sal) into salTotal from emp;
   
   -- Open the cursor 
   open cemp;

    loop
    --1, The total salary is greater than  5W
    exit when salTotal > 5000;
    
    -- Take an employee for a raise 
    fetch cemp into pempno ,psal;
    exit when cemp%notfund;
    
    -- raise 
    update  emp set sal=sal*1.1 when empno=pempno;
    -- The number of +1;
    countEmp := countEmp+1;
    
    -- The total salary after the increase  =  The total amount of wages before the increase  + sal * 0.1
    salTotal :=salTotal + psal * 0.1;
    end loop;
   
   -- Close the cursor 
   close cemp;
   
   commit;
end;
/

Case study 3

problem

Their thinking

Code

set serveroutput on;
declare 

  --  Define the cursor 
  cursor cdept is select dno,dname from dep;
  pdno dep.dno%type;
  pdname dep.dname%type;
  
  -- Define the cursor of grades 
  cursor  cgrade(coursename varchar2,depno number)
      is select grade from sc where cno=(select cno from course where cname = coursename)
                                    and sno = (select sno from student where dno = depno);
                                    
  pgrade sc.grade%type;
  -- The number of people in each segment 
  count1 number,count2 number,count3 number;
  
  -- Selection of each department  “ The average score of college physics students ”
  avggrade number;
  
  -- Course name 
  pcourseName varchar2 := " College Physics ";
begin 
    -- Open the cursor of the system 
    open cdept;
    loop 
    -- Take the information of a system 
    fetch cdept into pdno,pdname;
    exit when cdept%notfund;
    
    -- Initialization work 
    count1 := 0; count2 :=0; count3 :=0;
    
    -- The average grade of the Department 
    select avg(grade) into avggrade from sc where cno =(select cno from course where cname=pcoursename)
                      and sno in (select sno from student where dno =pdno )
     
     --  Taking the system , The student's grades of College Physics Department 
     open cgrade(pcourseName,pdno);
     
     loop
       -- Take a student's grade 
       fetch cgrade  into pgrade;
       exit when cgrade%notfound;
       
       -- Judge the range of achievement 
       if pgrade < 60 then count1 := count1+1;
       elseif pgrade >=60 and pgrade <=85 then count2 :=count2+1;
       else count3 := count3 + 1;
       end if;
       
       end loop;
       close cgrade;
       
       -- Save the current structure 
       insert into msg1 values(pcourseName,pdno,count1,count2,count3,avggrade);
       
       
    end loop;
end;
/
  

There is something wrong , Welcome to the discussion .
Last , Welcome to pay attention to my wechat , What do you like , Collection , Forwarding is my greatest encouragement .