復習內容:
PL/SQL的基本語法、記錄類型、流程控制、游標的使用、
異常處理機制、存儲函數/存儲過程、觸發器。
為方便大家跟著我的筆記練習,為此提供數據庫表文件給大家下載:點我下載
為了要有輸出的結果,在寫PL/SQL程序前都在先運行這一句:
set serveroutput on
結構:
declare
--聲明變量、類型、游標
begin
--程序的執行部分(類似於java裡的main()方法)
exception
--針對begin塊中出現的異常,提供處理的機制
--when...then...
--when...then...
end;
舉例1:
declare
v_sal number(10); (注意每句話後面別忘記了分號,跟java中的一樣)
begin
select salary into v_sal from employees where employee_id = 100;
dbms_output.put_line(v_sal);
end;
舉例2:
declare
v_sal number(10); (注意,這裡聲明的空間大小不能比原表中的小)
v_email varchar2(20);
v_hire_date date;
begin
select salary,email,hire_date into v_sal,v_email,v_hire_date from employees where employee_id =
100;
dbms_output.put_line(v_sal||','||v_email||','||v_hire_date);
end;
或者:
declare
v_sal employees.salary%type;
v_email employees.email%type;
v_hire_date employees.hire_date%type;
begin
select salary,email,hire_date into v_sal,v_email,v_hire_date from employees where employee_id =
100;
dbms_output.put_line(v_sal||','||v_email||','||v_hire_date);
end;
記錄:
declare
type emp_record is record(
v_sal employees.salary%type,
v_email employees.email%type,
v_hire_date employees.hire_date%type
);
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;
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 elseif 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.游標的使用(類似於java中的Iterator)
5.異常的處理
6.會寫一個存儲函數(有返回值)、存儲過程(沒有返回值)
7.會寫一個觸發器
復習記錄類型:
declare
type emp_record is record(
-- v_emp_id employees.employee_id%type,
-- v_sal employees.salary%type
v_emp_id number(10) := 120,
v_sal number(10,2) :=12000
);
v_emp_record emp_record;
begin
-- select employee_id,salary into v_emp_record from employees where employee_id = 123;
dbms_output.put_line('employee_id:'||v_emp_record.v_emp_id||' '||'salary:'||
v_emp_record.v_sal);
end;
也可以升級一下,要是想對表的所有列都輸出,則:(須注意輸出的列名要跟表中的列名要一樣)
declare
v_emp_record employees%rowtype;
begin
select * into v_emp_record from employees where employee_id = 123;
dbms_output.put_line('employee_id:'||v_emp_record.employee_id||' '||'salary:'||
v_emp_record.salary);
end;
使用記錄來執行update操作:
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;
流程控制:
查詢150號員工的工資,若其工資大於或等於10000 則打印‘salary >= 10000’;
若在5000到10000之間,則打印‘5000 <= salary <10000’;否則打印‘salary < 5000’
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('10000 > salary >= 5000');
else dbms_output.put_line('salary < 5000');
end if;
dbms_output.put_line('salary:'||v_sal);
end;
利用case ... when ... then ... when ...then ... else ... end實現上題;
declare
v_sal employees.salary%type;
v_temp varchar2(20);
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('salary:'||v_sal||' '||v_temp);
end;
查詢出122號員工的job_id,若其值為 ‘IT_PROG’, 則打印‘GRADE:A’
‘AC_MGT’, 則打印‘GRADE:B’
‘AC_ACCOUNT’, 則打印‘GRADE:B’
否則打印‘GRADE:D’
declare
v_job_id employees.job_id%type;
v_temp varchar2(20);
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('job_id:'||v_job_id||' '||v_temp);
end;
使用循環語句打印:1-100
declare
v_i number(5) :=1;
begin
loop
dbms_output.put_line(v_i);
exit when v_i >=100;
v_i := v_i + 1;
end loop;
end;
使用while實現:
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;
使用for...in...loop...end loop;實現:
begin
for c in 1..100 loop
dbms_output.put_line(c);
end loop;
end;
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;
利用for循環實現輸出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;
可以用goto改進一下:
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;
打印1-100的自然數,當打印到50時,跳出循環 ,輸出‘打印結束’:
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;
或者:
begin
for i in 1..100 loop
if i=50 then dbms_output.put_line('打印結束');
exit;
end if;
dbms_output.put_line(i);
end loop;
end;
游標:
打印出80部門的所有的員工的工資:salary:XXX
declare
v_sal employees.salary%type;
--定義游標
cursor emp_sal_cursor is select salary from employees where department_id = 80;
begin
--打開游標
open emp_sal_cursor;
--提取游標
fetch emp_sal_cursor into v_sal;
while emp_sal_cursor%found loop
dbms_output.put_line('salary:'||v_sal);
fetch emp_sal_cursor into v_sal;
end loop;
--關閉游標
close emp_sal_cursor;
end;
可以進行優化如下:
declare
v_empid employees.employee_id%type;
v_lastName employees.last_name%type;
v_sal employees.salary%type;
cursor emp_sal_cursor is select employee_id,last_name,salary from employees where
department_id = 80;
begin
open emp_sal_cursor;
fetch emp_sal_cursor into v_empid,v_lastName,v_sal;
while emp_sal_cursor%found loop
dbms_output.put_line('employee_id:'||v_empid||', '||'last_name:'||v_lastName||',
'||'salary:'||v_sal);
fetch emp_sal_cursor into v_empid,v_lastName,v_sal;
end loop;
close emp_sal_cursor;
end;
或者使用記錄再優化一下:
declare
type emp_record is record(
v_empid employees.employee_id%type,
v_lastName employees.last_name%type,
v_sal employees.salary%type
);
v_emp_record emp_record;
cursor emp_sal_cursor is select employee_id,last_name,salary from employees where
department_id = 80;
begin
open emp_sal_cursor;
fetch emp_sal_cursor into v_emp_record;
while emp_sal_cursor%found loop
dbms_output.put_line('employee_id:'||v_emp_record.v_empid||', '||'last_name:'||
v_emp_record.v_lastName||', '||'salary:'||v_emp_record.v_sal);
fetch emp_sal_cursor into v_emp_record;
end loop;
close emp_sal_cursor;
end;
可以使用for循環最優化:(注意:在for循環中它會自動的打開游標、提取游標,當提取完裡面的數據後也會自動
的關閉游標)
declare
cursor emp_sal_cursor is select employee_id,last_name,salary from employees where
department_id = 80;
begin
for c in emp_sal_cursor loop
dbms_output.put_line('employee_id:'||c.employee_id||', '||'last_name:'||c.last_name||',
'||'salary:'||c.salary);
end loop;
end;
利用游標,調整公司中員工的工資:
工資范圍 調整基數
0 - 5000 5%
5000 - 10000 3%
10000 - 15000 2%
15000 - 1%
實現:
declare
cursor emp_cursor is select employee_id,salary from employees;
v_empid employees.employee_id%type;
v_sal employees.salary%type;
v_temp number(4,2);
begin
open emp_cursor;
fetch emp_cursor into v_empid,v_sal;
while emp_cursor%found loop
if v_sal < 5000 then v_temp:=0.05;
elsif v_sal < 10000 then v_temp:=0.03;
elsif v_sal < 15000 then v_temp:=0.02;
else v_temp:=0.01;
end if;
dbms_output.put_line(v_empid||','||v_sal);
update employees
set salary = salary * (1+v_temp)
where employee_id = v_empid;
fetch emp_cursor into v_empid,v_sal;
end loop;
close emp_cursor;
end;
用for循環實現
declare
cursor emp_cursor is select employee_id,salary from employees;
v_temp number(4,2);
begin
for c in emp_cursor loop
if c.salary <5000 then v_temp:=0.05;
elsif c.salary <10000 then v_temp:=0.03;
elsif c.salary <15000 then v_temp:=0.02;
else v_temp:=0.01;
end if;
update employees
set salary = salary * (1+v_temp)
where employee_id = c.employee_id;
end loop;
end;
隱式游標:更新員工salary(漲工資10),如果該員工沒有找到,則打印“查無此人”信息:
begin
update employees
set salary = salary + 10
where employee_id = 1001;
if sql%notfound then dbms_output.put_line('查無此人');
end if;
end;
異常:
預定義異常:(有24個預定義異常,可查表)
declare
v_sal employees.salary%type;
begin
select salary into v_sal from employees
where employee_id > 100;
dbms_output.put_line(v_sal);
exception
when too_many_rows then dbms_output.put_line('輸出的行數過多');
when others then dbms_output.put_line('出現其它的異常了');
end;
非預定義異常:
declare
e_deleteid_exception exception;
pragma exception_init(e_deleteid_exception,-2292);
begin
delete from employees
where employee_id = 100;
exception
when e_deleteid_exception then dbms_output.put_line('違反了完整性約束,故不能刪除此用戶');
when others then dbms_output.put_line('出現其它的異常了');
end;
用戶自定義異常:
declare
e_sal_hight exception;
v_sal employees.salary%type;
begin
select salary into v_sal from employees where employee_id = 100;
if v_sal > 10000 then raise e_sal_hight;
end if;
exception
when e_sal_hight then dbms_output.put_line('工資太高了');
when others then dbms_output.put_line('出現其它的異常了');
end;
通過select...into...查詢某人的工資,若沒找到則打印出“未找到此數據”:
declare
v_sal employees.salary%type;
begin
select salary into v_sal from employees where employee_id = 1001;
exception
when no_data_found then dbms_output.put_line('未找到此數據');
when others then dbms_output.put_line('出現其它的異常了');
end;
更新指定員工工資,如工資小於300,則加100,對NO_DATA_FOUND異常,TOO_MANY_ROWS進行處理。
declare
v_sal employees.salary%type;
begin
select salary into v_sal from employees where employee_id = 1001;
if v_sal < 300 then update employees set salary = salary + 100 where employee_id =101;
end if;
exception
when no_data_found then dbms_output.put_line('未找到此數據');
when too_many_rows then dbms_output.put_line('輸出的行數太多了');
when others then dbms_output.put_line('出現其它的異常了');
end;
自定義異常:
更新指定員工工資,增加100;若指定員工不在,則拋出異常:NO_RESULT;
declare
no_result exception;
begin
update employees set salary = salary + 100 where employee_id = 1001;
if sql%notfound then raise no_result;
end if;
exception
when no_result then dbms_output.put_line('查無此數據,更新失敗');
when others then dbms_output.put_line('出現其它異常');
end;
存儲過程:
寫個簡單的hello_world存儲函數
create or replace function hello_world
return varchar2
is (相當於declare,可以在其後面定義變量、記錄、游標)
begin
return 'helloworld';
end;
存儲函數的調用:
begin
dbms_output.put_line(hello_world);
end;
或者:
select hello_world from dual;
帶參數的存儲函數:
create or replace function hello_world1(v_logo varchar2)
return varchar2
is
begin
return 'helloworld'||v_logo;
end;
調用:
select hello_world1('shellway') from dual
或者:
begin
dbms_output.put_line(hello_world1('shellway'));
end;
定義一個獲取系統時間的函數:
create or replace function get_sysdate
return varchar2
is
begin
return to_char(sysdate,'yyyy-MM-dd HH24:mi:ss');
end;
定義帶參數的函數,兩個數相加
create or replace function add_param(v_num1 number,v_num2 number)
return number
is
v_num3 number(10);
begin
v_num3 := v_num1 + v_num2;
return v_num3;
end;
調用:
select add_param(2,5) from dual;
或者:
begin
dbms_output.put_line(add_param(5,4));
end;
定義一個函數:獲取給定部門的工資總和,要求:部門號定義為參數,工資總額為返回值:
create or replace function get_sal(dept_id number)
return number
is
v_sumsal number(10) := 0;
cursor salary_cursor is select salary from employees where department_id = dept_id;
begin
for c in salary_cursor loop
v_sumsal := v_sumsal + c.salary;
end loop;
return v_sumsal;
end;
調用:
select get_sal(80) from dual;
定義一個函數:獲取給定部門的工資總和 和 該部門的員工總數(定義為OUT類型的參數)。
要求:部門號定義為參數,工資總額定義為返回值。
create or replace function get_sal(dept_id number,total_count out number)
return number
is
v_sumsal number(10) := 0;
cursor salary_cursor is select salary from employees where department_id = dept_id;
begin
total_count := 0;
for c in salary_cursor loop
v_sumsal := v_sumsal + c.salary;
total_count := total_count + 1;
end loop;
return v_sumsal;
end;
調用:
declare
v_count number(4);
begin
dbms_output.put_line(get_sal(80,v_count));
dbms_output.put_line(v_count);
end;
定義一個存儲過程:獲取給定部門的工資總和(通過out參數),要求部門號和工資總額定義為參數。
(注意:存儲過程和存儲函數是不一樣的,存儲函數有返回值而存儲過程沒有,調用時候存儲過程直接調用)
create or replace procedure get_sal1(dept_id number,sumsal out number)
is
cursor salary_cursor is select salary from employees where department_id = dept_id;
begin
sumsal := 0;
for c in salary_cursor loop
sumsal := sumsal + c.salary;
end loop;
dbms_output.put_line(sumsal);
end;
調用:
declare
v_sal number(10):=0;
begin
get_sal1(80,v_sal);
end;
對給定部門(作為輸入參數)的員工進行加薪操作,若其到公司的時間在(?,95)期間,為其加薪5%
(95,98) 3%
(98,?) 1%
得到以下返回結果:為此次加薪公司每月額外付出多少成三(定義一個OUT型的輸出參數)
create or replace procedure add_sal(dept_id number,temp out number)
is
cursor sal_cursor is select employee_id,salary,hire_date
from employees where department_id = dept_id;
v_temp number(4,2):=0;
begin
temp := 0;
for c in sal_cursor loop
if to_char(c.hire_date,'yyyy') < '1995' then v_temp:=0.05;
elsif to_char(c.hire_date,'yyyy') < '1998' then v_temp:=0.03;
else v_temp:=0.01;
end if;
update employees
set salary = salary * (1+v_temp)
where employee_id = c.employee_id;
temp := temp + c.salary*v_temp;
end loop;
dbms_output.put_line(temp);
end;
調用:
declare
v_i number(10):=0;
begin
add_sal(80,v_i);
end;
觸發器:
觸發事件:在INSERT,UPDATE,DELETE情況下會觸發TRIGGER
觸發時間:該TRIGGER是在觸發事件發生之前(BEFORE)還是之後(AFTER)
觸發器本身:該TRIGGER被觸發之後的目的和意圖,正是觸發器本身要做的事情,如PL/SQL塊
觸發頻率:有語句級(STATEMENT)觸發器和行級(ROW)觸發器
寫一個簡單的觸發器:
create or replace trigger update_emp_trigger
after
update on employees
for each row (行級觸發器,即每更新一條記錄就會輸出一次'helloworld',若沒有這語句則是語句級觸發器)
begin
dbms_output.put_line('helloworld');
end;
使用:new,:old修飾符:
1、
create table emp1
as
select employee_id,salary,email from employees where department_id = 80;
2、
create or replace trigger update_emp_trigger2
after
update on emp1
for each row
begin
dbms_output.put_line('old salary:'||:old.salary||'new salary:'||:new.salary);
end;
3、
update emp1 set salary = salary + 100 ;
編寫一個觸發器,在對my_emp記錄進行刪除的時候,在my_emp_bak表中備份對應的記錄
1、創建my_emp表:
create table my_emp
as
select employee_id,salary from employees ;
2、創建my_emp_bak表:
create table my_emp_bak
as
select employee_id,salary from employees where 1=2;
3、檢查創建的表中的記錄:
select * from my_emp
select * from my_emp_bak
4、創建一個觸發器:
create or replace trigger delete_emp_trigger
before
delete on my_emp
for each row
begin
insert into my_emp_bak
values(:old.employee_id,:old.salary);
end;
5、執行含有觸發器時間的語句:
delete from my_emp
6、檢查觸發器執行後的結果:
select * from my_emp
select * from my_emp_bak
吾時而躬身自省,自省使知已之不足,知不足而奮起,未為晚也!
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《Oracle PL/SQL從入門到精通》以面向應用為原則,深入淺出地介紹了Oracle平台上使用PL/SQL語言進行數據庫開發的技術。通過大量的示例,詳細介紹了PL/SQL的語言特性、使用技巧,同時配以兩個在實際工作中的案例深入地剖析了使用PL/SQL進行Oracle開發的方方面面。 《Oracle PL/SQL從入門到精通》附帶1張DVD光盤,內容為作者為《Oracle PL/SQL從入門到精通》錄制的全程語音教學視頻及《Oracle PL/SQL從入門到精通(附光盤)》所涉及的源代碼。
《Oracle PL/SQL從入門到精通》分為5大篇共20章。涵蓋的內容主要有PL/SQL語言基礎、開發環境、變量與類型、控制語句、數據表的管理和查詢、數據表的操縱、使用PL/SQL的記錄與集合、各種內置函數、游標、事務處理、異常處理、子程序、包、面向對象的開發等技術點。通過示例性的代碼,由淺入深,詳細介紹了每一個技術要點在實際工作中的應用,對各種技術要點的應用場合進行了細致的分析。