plsql編程筆記

學習計劃：

1.pl/sql 基本的語法格式
2.記錄類型 type ... is record(,,,,);
3.流程控制
       3.1 條件判斷（兩種）
           方式一：if .... then elsif then ... else ... end if;
           方式二：case ... when ... then ... end;
       3.2 循環結構（三種）
           方式一：loop ... exit when ... end loop;
           方式二：while ... loop ... end loop;
           方式三：for i in ... loop ... end loop;
       3.3 goto，exit
4.遊標的使用（類似java中Iterator）
5.異常的處理（三種方式）
6.存儲函數（有返回值）function，存儲過程（沒有返回值）procedure
7.觸發器 trigger
8.set serveroutput on數據設置。

語法：

declare
-- 變量 ，記錄類型等的聲明
begin
-- 程序的執行部分
exception
-- 異常的處理
end;

實例1：

declare
--聲明一個記錄類型
  type emp_record is record(
    v_sal employees.salary%type,
    v_email employees.email%type,
    v_hire_date employees.hire_date%type
  );
  --定義一個記錄類型的成員變量
  v_emp_record emp_record;
begin
  select salary,email,hire_date into v_emp_record from employees where employee_id = 100;
  dbms_output.put_line(v_emp_record.v_sal||','||v_emp_record.v_email||','||v_emp_record.v_hire_date);
end;

實例2

declare
-- 變量 ，記錄類型等的聲明
   v_sal number(8,2) := 0;
   v_emp_id number(10);
   v_email varchar2(20);
   v_hire_date date;
begin
-- 程序的執行部分
   select salary,employee_id,email,hire_date into v_sal,v_emp_id,v_email,v_hire_date from employees where employee_id = 123;
   
   dbms_output.put_line('員工編號：'||v_emp_id||'工資：'||v_sal||'郵箱：'||v_email||'入職時間：'||v_hire_date);
-- exception
-- 異常的處理
end;

實例3：用記錄類型升級

declare
-- 變量 ，記錄類型等的聲明
   type emp_record is record(
     v_sal number(8,2) := 0,
     v_emp_id number(10),
     v_email varchar2(20),
     v_hire_date date
   );
  v_emp_red emp_record;
begin
-- 程序的執行部分
   select salary,employee_id,email,hire_date into v_emp_red from employees where employee_id = 123;
   
   dbms_output.put_line('員工編號：'||v_emp_red.v_emp_id||'工資：'||v_emp_red.v_sal||'郵箱：'||v_emp_red.v_email||'入職時間：'||v_emp_red.v_hire_date);
-- exception
-- 異常的處理
end;

實例4：

declare
  type salary_record is record(
       v_name varchar2(20),
       v_salary number(10,2)
  );
  v_sal_record salary_record;
begin
  v_sal_record.v_name := '劉德華';
  v_sal_record.v_salary := 120000;
  
  dbms_output.put_line('姓名：'||v_sal_record.v_name||'薪資：'||v_sal_record.v_salary);
end;

實例5：

declare
-- 變量 ，記錄類型等的聲明
/*
   type emp_record is record(
     v_sal number(8,2) := 0,
     v_emp_id number(10),
     v_email varchar2(20),
     v_hire_date date
   );
  v_emp_red emp_record;
  */
  v_emp_record employees%rowtype;
begin
-- 程序的執行部分
 --  select salary,employee_id,email,hire_date into v_emp_red from employees where employee_id = 123;
   select * into v_emp_record from employees where employee_id = 123;
   dbms_output.put_line('員工編號：'||v_emp_record.employee_id||'工資：'||v_emp_record.salary||'郵箱：'||v_emp_record.email||'入職時間：'||v_emp_record.hire_date);
-- exception
-- 異常的處理
end;

實例6：

declare
  v_emp_id number(10);
begin
  v_emp_id := 123;
  update employees set salary = salary+100 where employee_id = v_emp_id;
  
  dbms_output.put_line('執行成功！');
end;

實例7：流程控制語句

declare
  v_sal employees.salary%type;
begin
  select salary into v_sal from employees where employee_id = 150;
  if v_sal >= 10000 then dbms_output.put_line('salary>10000');
  elsif v_sal >= 5000 then dbms_output.put_line('5000<salary<10000');
  else dbms_output.put_line('salary<5000');
  end if;
end;

升級版：

declare
  v_sal employees.salary%type;
  v_temp varchar2(50);
begin
  select salary into v_sal from employees where employee_id = 150;
  if v_sal >= 10000 then v_temp := 'salary>10000';
  elsif v_sal >= 5000 then v_temp := '5000<salary<10000';
  else v_temp :='salary<5000';
  end if;
  dbms_output.put_line(v_temp);
end;

實例7：case  when  ... then

declare
  v_sal employees.salary%type;
  v_temp varchar2(50);
begin
  select salary into v_sal from employees where employee_id = 150;
  v_temp := case trunc(v_sal/5000) when 0 then 'salary<5000'
             when 1 then '5000<salary<10000'
             else 'salary>10000'
  end;
  dbms_output.put_line(v_temp);
end;

實例8：

declare
  v_job_id employees.job_id%type;
  v_temp varchar2(10);
begin
  select job_id into v_job_id from employees where employee_id = 122;
  v_temp := 
         case v_job_id when 'IT_PROG' then 'A'
                       when 'AC_MGT' then 'B'
                       when 'AC_ACCOUNT' then 'C'
                       ELSE 'D'
         end;
  dbms_output.put_line(v_job_id||','||v_temp);
end;

實例9：

declare
--初始化條件 循環體 循環條件 迭代條件
--聲明變量
        v_i number(5) := 1;
begin
        loop
        --循環體
            dbms_output.put_line(v_i);
            --迭代條件
             v_i := v_i +1;
        --循環條件
        exit when v_i > 100;
        
        end loop;
end;

實例10：

declare
  v_i number(5) := 1;
begin
  while v_i <= 100 loop
        dbms_output.put_line(v_i);
        v_i := v_i + 1;
  end loop;
end;

實例11：

declare
  v_s number(5) := 1;
  v_e number(5) := 100;
begin
  for c in v_s..v_e loop
      dbms_output.put_line(c);
  end loop;
end;

declare
  v_s number(5) := 1;
  v_e number(5) := 100;
begin
  for c in reverse v_s..v_e loop
      dbms_output.put_line(c);
  end loop;
end;

實例12：

--輸出2-100之間的質數
declare
   v_i number(3) := 2;
   v_j number(3) := 2;
   v_flag number(1) := 1;
begin
   while v_i <= 100 loop
         while v_j <= sqrt(v_i) loop
               if mod(v_i,v_j) = 0 then v_flag := 0;
               end if;
               v_j := v_j + 1;
         end loop;
         if v_flag = 1 then dbms_output.put_line(v_i);
         end if;
         v_j := 2;
         v_i := v_i + 1;
         v_flag := 1;
    end loop;
end;

實例13：

--輸出2-100之間的質數
declare
  v_flag number(1) := 1;
begin
  for v_i in 2..100 loop
      for v_j in 2..sqrt(v_i) loop
       if mod(v_i,v_j) = 0 then v_flag := 0;
        end if;
      end loop; 
      if v_flag = 1 then dbms_output.put_line(v_i); 
      end if; v_flag := 1; 
  end loop; 
end;

升級版：

--輸出2-100之間的質數
declare
  v_flag number(1) := 1;
begin
  for v_i in 2..100 loop
      for v_j in 2..sqrt(v_i) loop
          if mod(v_i,v_j) = 0 then v_flag := 0;
          goto label;
          end if;
      end loop;
      <<label>>
      if v_flag = 1 then dbms_output.put_line(v_i);
      end if;
      v_flag := 1;
   end loop; 
end;

begin
  for i in 1..100 loop
      if i = 50 then goto label;
      end if;
      dbms_output.put_line(i);
  end loop;
  <<label>>
  dbms_output.put_line('打印結束');
end;

遊標：

declare
  v_sal employees.salary%type;
  v_emp_id employees.employee_id%type;
  --定義遊標
  cursor emp_sal_cursor is select salary,employee_id from employees where department_id = 80;
begin
  --打開遊標
  open emp_sal_cursor;
  --提取遊標
  fetch emp_sal_cursor into v_sal,v_emp_id;
  
  while emp_sal_cursor%found loop
        dbms_output.put_line('員工號：'||v_emp_id||'的工資：'||v_sal);
        fetch emp_sal_cursor into v_sal,v_emp_id;
  end loop;
  --關閉遊標
  close emp_sal_cursor;
end;

for遊標：

declare
 -- v_sal employees.salary%type;
 -- v_emp_id employees.employee_id%type;
  --定義遊標
  cursor emp_sal_cursor is select salary,employee_id from employees where department_id = 80;
begin
/*
  --打開遊標
  open emp_sal_cursor;
  --提取遊標
  fetch emp_sal_cursor into v_sal,v_emp_id;
  
  while emp_sal_cursor%found loop
        dbms_output.put_line('員工號：'||v_emp_id||'的工資：'||v_sal);
        fetch emp_sal_cursor into v_sal,v_emp_id;
  end loop;
  --關閉遊標
  close emp_sal_cursor;
  */
  for c in emp_sal_cursor loop
      dbms_output.put_line('員工號：'||c.employee_id||'的工資：'||c.salary);
  end loop;
end;

實例：set

select employee_id,department_id from emp_01
union
select employee_id,department_id from emp_02

select employee_id,department_id from emp_01
union all
select employee_id,department_id from emp_02

select employee_id emp_id,department_id dept_id from emp_01
intersect
select employee_id,department_id from emp_02
order by emp_id desc

select employee_id emp_id,department_id dept_id,to_char(null) from emp_01
minus
select to_number(null),department_id,department_name from departments

select employee_id emp_id,department_id dept_id,to_char(null) from emp_01
union all
select to_number(null),department_id,department_name from departments

/*select department_id 
from departments 
where department_id not in (
      select DISTINCT department_id from employees where job_id = 'ST_CLERK'
)*/

SELECT department_id from departments
minus
select department_id
from employees
where job_id = 'ST_CLERK'

column a_dummy noprint;

select job_id,department_id,1 a_dummy from employees
where department_id = 10
union
select job_id,department_id,2 from employees
where department_id = 50
union
select job_id,department_id,3 from employees
where department_id = 20
order by 3 asc

select last_name,department_id,to_char(null)
from employees
union
select to_char(null),department_id,department_name
from departments

--查詢last_name爲Chen的manager的信息


select employee_id,last_name
from employees

where employee_id=(select manager_id 
from employees
where last_name = 'Chen')

多列子查詢：

select employee_id,manager_id,department_id from 
employees 
where (manager_id,department_id) in (select manager_id,department_id from employees
where employee_id in (141,174)) 

select employee_id,manager_id,department_id from 
employees where manager_id in (select manager_id from employees
where employee_id in (141,174)) 
and department_id in (select department_id from employees
where employee_id in (141,174))

--計算比本部門平均工資高的員工的信息
select last_name,department_id,salary,(select avg(salary) from employees e3 where e1.department_id = e3.department_id group by department_id) avgsal
from employees e1 where salary > (
                            select avg(salary) 
                            from employees e2 
                            where e1.department_id = e2.department_id )

--計算比本部門平均工資高的員工的信息


select last_name,e1.department_id,e1.salary,e2.salaravg
from employees e1,(select department_id,avg(salary) salaravg from employees group by department_id) e2
where e1.department_id = e2.department_id and salary>e2.salaravg

select employee_id,last_name,(case department_id 
                                   when (select department_id from departments 
                                   where location_id = 1800) then 'Canada'
                                   else 'USA' end)location

from employees

select employee_id,last_name
from employees emp
order by (select department_name
         from departments dept
         where emp.department_id = dept.department_id
         ) asc

select employee_id,last_name,job_id
from employees emp
where 2<= (
          select count(*) from job_history
          where employee_id = emp.employee_id
          )

-- 查詢公司管理者的employee_id，last_name，job_id,department_id信息
select employee_id,last_name,job_id,department_id
from employees emp
where emp.employee_id in (
                        select manager_id
                        from employees mana
                        where emp.employee_id = mana.manager_id
                        )

-- 查詢公司管理者的employee_id，last_name，job_id,department_id信息
select distinct emp.employee_id,emp.last_name,emp.job_id,emp.department_id
from employees emp,employees mana
where emp.employee_id = mana.manager_id

-- 查詢公司管理者的employee_id，last_name，job_id,department_id信息
select emp.employee_id,emp.last_name,emp.job_id,emp.department_id
from employees emp
where exists (
             select 'A' from employees mana
             where emp.employee_id = mana.manager_id
             )

--查詢departments表中，不存在與employees表中的部門的department_id和department_name
select department_id,department_name
from departments dept
where not exists(
            select 'c' from employees
            where department_id = dept.department_id
            )

--查詢departments表中，不存在與employees表中的部門的department_id和department_name
select department_id
from departments dept
minus
select department_id
from employees

--查詢公司中工資比Abel高的員工的工資

/*select employee_id,salary
from employees
where salary > (
               select salary from employees 
               where last_name = 'Abel'
               )*/
               
with Abel_sal as (
                 select salary from employees
                 where last_name = 'Abel'
                 )
select employee_id,salary
from employees
where salary > (
               select salary from Abel_sal
               )

--查詢公司中各部門的總工資大於公司中各部門的平均總工資的部門信息
with dept_sum_sal as (
select department_name,sum(salary) sum_sal
from employees e,departments d
where e.department_id = d.department_id
group by department_name),
dept_avg_sal as (
select sum(sum_sal)/count(*) avg_sal from dept_sum_sal
)

select * 
from dept_sum_sal 
where sum_sal > (
                 select avg_sal 
                 from dept_avg_sal
                )
order by department_name

--1.  查詢員工的last_name, department_id, salary.其中員工的salary,department_id
--與有獎金的任何一個員工的salary,department_id相同即可

select last_name,department_id,salary
from employees
where (salary,department_id) in (
                                select salary,department_id
                                from employees
                                where commission_pct is not null
                                )

--2.  選擇工資大於所有JOB_ID = 'SA_MAN'的員工的工資的員工的last_name, job_id, salary

select last_name,job_id,salary
from employees
where salary > all(
                   select salary from 
                   employees 
                   where job_id = 'SA_MAN'
                   )

--3.  選擇所有沒有管理者的員工的last_name
/*
select last_name 
from employees
where manager_id is null
*/

select last_name
from employees emp
where not exists (
                 select 'c' from employees
                 where employee_id = emp.manager_id
                 )