Mysql預存程序執行個體

## **********first test,procedure**********
#<1>
use testprocedure;

delimiter //

create procedure simpleproce1 (out par1 int)
begin
 select count(*) into par1 from proce;
end
//

delimiter ;
call simpleproce1(@a);

select @a;

#<2>,每次只有單一的行可以被取回select id,name into par1,par2 from proce LIMIT 1;中的LIMIT 1;

use testprocedure;

delimiter //

DROP procedure IF EXISTS simpleproce2

create procedure simpleproce2 (out par1 int,out par2 char(30))
begin
 select id,name into par1,par2 from proce LIMIT 1;
end
//

delimiter ;
call simpleproce2(@a,@b);

select @a,@b;

 
## *********second test,function************
#<3>
delimiter //

DROP FUNCTION IF EXISTS hello
//

create function hello(s char(20)) returns char(50)
  return concat('Hello, ',s,'!');
//

delimiter ;
select hello('world');

show create function testprocedure.hello/G

  #它返回子程式的特徵，如資料庫，名字，類型，建立者及建立和修改日期
show function status like 'hello'/G

#<4>
#注意name不能和欄位名相同
delimiter //
DROP procedure IF EXISTS test //

CREATE PROCEDURE test ()
  BEGIN
    DECLARE name VARCHAR(5) DEFAULT 'bob';
    DECLARE newname VARCHAR(5);
    DECLARE xid INT;
   
    SELECT name,id INTO newname,xid
      FROM proce WHERE name = name;
    SELECT newname;
  END;
//

call test1() //

#***
delimiter //
DROP procedure IF EXISTS test2 //

CREATE PROCEDURE test2 ()
  BEGIN
   
    DECLARE newname VARCHAR(5);
    DECLARE xid INT;
   
    SELECT name,id INTO newname,xid
      FROM proce limit 1;
    SELECT newname,xid;
  END;
//

call test2() //

#<5>
use testprocedure;
CREATE PROCEDURE p1 () SELECT * FROM proce;

call p1();

#<6>注意此處的handler是設定SQLSTATE值，SQLWARNING是對所有以01開頭的SQLSTATE代碼的速記
#NOT FOUND是對所有以02開頭的SQLSTATE代碼的速記
#SQLEXCEPTION是對所有沒有被SQLWARNING或NOT FOUND捕獲的SQLSTATE代碼的速記
#DECLARE CONTINUE HANDLER聲明CONTINUE異常處理
#事實上這裡的23000SQLSTATE是更常用的，當外鍵約束出錯或主鍵約束出錯就被調用了。
#當沒有發生該23000異常時， select @x2的值將是null,而不是1,
#並且後面的第2個語句執行時將會報主鍵約束錯誤，此時@x2=1,@x=4,雖然第2句有了異常，但是後面的語句繼續執行
#儲存到資料的資料是3,test3和5,test5

use testprocedure;
delimiter //
DROP procedure IF EXISTS handlerdemo
//

create procedure handlerdemo()
begin
 declare continue handler for sqlstate '23000' set @x2=1;
 set @x=1;
 insert into proce values(3,'test3');
 set @x=2;
 insert into proce values(3,'test4');
 set @x=3;
 insert into proce values(5,'test5');
 set @x=4;
end;
//

call handlerdemo()//

select @x //
select @x2 //

## ************游標****************
#<7>游標必須在聲明處理常式之前被聲明，並且變數和條件必須在聲明游標或處理常式之前被聲明
#在這裡先聲明變數a,b,c,後聲明cursor
create procedure curdemo()
begin
 declare done int default 0;
 declare a char(16);
 declare b,c int;
 declare cur1 cursor for select id,name from proce;
 declare cur2 cursor for select id from proce2;
 declare continue handler for sqlstate '02000' set done=1;
 
 open cur1;
 open cur2;

 repeat
  fetch cur1 into b,a;
  fetch cur2 into c;
  if not done then
   if b<c then
     insert into proce3 values(b,a);
   else
     insert into proce3 values(c,a);
   end if;
  end if;
 until done end repeat;
 
 close cur1;
 close cur2;
end

## **************** Case *******************
#<8>when ... then ;case ... end case;
delimiter //
DROP procedure IF EXISTS p13
//
create procedure p13(in par1 int)
begin
 declare var1 int;
 set var1=par1+1;
 
 case var1
  when 0 then insert into casetest values(17);
  when 1 then insert into casetest values(18);
  else insert into casetest values(19);
 end case;
end;
//

call p13(-1)//
call p13(0)//
call p13(1)//
call p13(null)//

## **************** while ****************
#<9>while ... do ... end while;為了防止null的錯誤，set v=0是必須的
delimiter //
DROP procedure IF EXISTS p14
//

create procedure p14()
begin
  declare v int;
  set v=0;
  while v < 5 do
      insert into casetest values (v);
      set v=v+1;
  end while;
end;//

call p14()//

## ***************** repeat *****************
#<10>repeat ...until ... end repeat; 是執行後檢查（until v>=5），而while是執行前檢查(while v<5)
delimiter //
DROP procedure IF EXISTS p15
//

create procedure p15()
begin
  declare v int;
  set v=0;
  repeat
    insert into casetest values(v);
    set v=v+1;
  until v >=5

  end repeat;
 
end;
//

call p15()//

## ***************** loops *****************
#<11> loop 和while一樣不需要初始條件，同時和repeat一樣不需要結束條件
 #      loop_label: loop
 #      ...
 #       if .. then
 #       leave loop_label
 #       end if
 #      end loop

delimiter //
DROP procedure IF EXISTS p16
//

create procedure p16()
begin
  declare v int;
  set v=0;
  loop_label: loop
    insert into casetest values(v);
    set v=v+1;
    if v >=5 then
      leave loop_label;
    end if;
  end loop;
end;//

call p16()//

## ***************** Labels *****************
# <12>labels標號； 注意此處的until 0=0後面沒有分號“;”
delimiter //
DROP procedure IF EXISTS p17//

create procedure p17()
label_1:begin

label_2:while 0=1 do leave label_2; end while;

label_3:repeat leave label_3;until 0=0 end repeat;

label_4:loop leave label_4; end loop;

end;//

call p17()//

#<13>labels 標號結束符；
delimiter //
DROP procedure IF EXISTS p18//

create procedure p18()
label_1:begin

 label_2:while 0=1 do leave label_2; end while label_2;

 label_3:repeat leave label_3;until 0=0 end repeat label_3;

 label_4:loop leave label_4; end loop label_4;

end label_1;//

call p18()//

#<14>leave和labels 跳出和標號;leave 使程式跳出複雜的語句
delimiter //
DROP procedure IF EXISTS p19//

create procedure p19(par char)

label_1:begin
label_2:begin
label_3:begin

 if par is not null then
 if par='a' then leave label_1;
 else
   begin
     if par='b' then
       leave label_2;
     else
       leave label_3;
     end if;
   end;
 end if;
 end if;

end label_3;
end label_2;
end label_1;

//

call p19('a')//

#<15>iterate迭代，必須用leave;iterate意思是重新開始複合陳述式，相當於 continue
#該結果中3將不被儲存到資料庫表中
delimiter //
DROP procedure IF EXISTS p20//

create procedure p20()
begin
  declare v int;
  set v=0;
  loop_label:loop

    if v=3 then
      set v=v+1;
      iterate loop_label;
    end if;
    insert into casetest values(v);
    set v=v+1;

    if v>=5 then
      leave loop_label;
    end if;

  end loop loop_label;
end;//

call p20()//

#<16>Grand combination大組合

delimiter //
DROP procedure IF EXISTS p21//

create procedure p21(in par1 int,out par2 int)
language sql deterministic sql security invoker
begin
  declare v int;

  label goto_label;

  start_label:loop
    if v=v then
      leave start_label;
    else
      iterate start_label;
    end if;
  end loop start_label;
 
  repeat
    while 1=0 do begin end;
    end while;
  until v=v
  end repeat;

  goto goto_label;

end;
//

call p21()//

## **************** trigger ***************************
#<17>
use testprocedure;

CREATE TABLE trig1(a1 int);
CREATE TABLE trig2(a2 int);
CREATE TABLE trig3(a3 int not null AUTO_INCREMENT PRIMARY KEY);

CREATE TABLE trig4(
  a4 INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
  b4 INT DEFAULT 0
);

insert into trig3(a3) values(null),(null),(null),(null),(null),(null),(null),(null),(null),(null);
insert into trig4(a4) values(0),(0),(0),(0),(0),(0),(0),(0),(0),(0);

delimiter //
DROP trigger trigtest//

create trigger trigtest before insert on trig1
for each row begin
  insert into trig2 set a2=NEW.a1;
  delete from trig3 where a3=NEW.a1;
  update trig4 set b4=b4+1 where a4=NEW.a1;
end;
//

delimiter ;

INSERT INTO trig1 VALUES(1), (3), (1), (7), (1), (8), (4), (4);