Oracle Pl/SQL编程基础

Pl/SQL简介

　　提高应用程序的运行性能,

　　提供模块化的程序设计,

　　自定义标示符,　　

　　具有过程语言控制结构,　　

　　良好的兼容性,

　　处理运行错误.

Pl/SQL语言基础

　　sql是关系数据库的基本操作语言.

　　　　sql语言包括:数据查询,数据操纵,事物控制,数据定义和数据控制语言登5个部分.

Pl/SQL块

　　Pl/SQ的基本单元

DECLARE
/*定义部分-变量,常量,游标,列解*/
BEGIN
/*定义部分-PL/SQL语句*/
EXCEPTION
/*异常处理部分-处理运行错误*/
END;/*结束块标志*/

注意:"="表示判断,":="赋值,"||"连接.

标量类型

　　VARCHAR2(n),CHAR(n),NUMBER(p,s),DATE,TIMESTAMP,BOOLEAN

if语句

-- 结构:   if   条件  then    = 表示判断
     --    end if;
select * from scott.emp;

declare
v_name varchar(30);
begin
  select scott.emp.ename into v_name from scott.emp where scott.emp.empno = 7499;
  if v_name = 'SMITH' then
    begin
    dbms_output.put_line('没有该员工');
    end;
  elsif xxx  then
    begin
    end;
  else
    dbms_output.put_line('员工姓名' || v_name);
  end if;
end;

CASE语句

-- case
switch(xxx) {
         case '':
           break;
         default:
}

case xxx
  when xxx  then
    -- 处理语句
  when xxx  then
    -- 
  else
end case;
    
select ename,
  case deptno
    when 10 then
      '综合部门'
    when 20 then '技术部门'
    when 30 then '市场部门'
    else '其他部门'
  end case from scott.emp;

循环语句(loop,while,for)

　　条件:循环初始值,循环结束之,改变值.　

-- 循环  loop  while  for    循环起始值    循环结束条件    改变值
declare
i int := 0;
begin
loop
  i := i + 1;
  dbms_output.put_line(i);
  exit when i = 10; 
end loop;
end;

declare
i int := 0;
begin
while i < 101 loop
  i := i + 1;
  dbms_output.put_line(i);
end loop;
end;

declare
begin
for i in reverse 1..101 loop
  dbms_output.put_line(i);
end loop;
end;

select emp.ename from emp;
--  类型   存储更多的数据   %type   %rowtype  record(自定义类型)   table  varray
declare
v_name emp.ename%type;
begin
  select emp.ename into v_name from emp where empno = 7369;
  dbms_output.put_line(v_name);
end;


declare
v_name dept%rowtype;
begin
  select * into v_name from dept where deptno = 10;
  dbms_output.put_line(v_name.deptno || v_name.dname);
end;

declare
type r_name is record (
    v_dname dept.dname%type,
    v_loc dept.loc%type
);
rec_v r_name;
begin
    select dname,loc into rec_v.v_dname,rec_v.v_loc from dept where deptno = 10;
    dbms_output.put_line(rec_v.v_dname || rec_v.v_loc);
end;

select * from dept

异常处理

-- 异常处理

exception
  when 异常 then
    --
  when 异常 then
  
  when others then

-- 预定义异常
declare
v_name emp.ename%type;
begin
  select to_number(ename) into v_name from emp where empno = &empno;
  exception
    when no_data_found then   -- ora-01403
      dbms_output.put_line('没有数据');
    when invalid_number then   -- ora-01403
      dbms_output.put_line('转换异常');
end;

-- 非预定义异常 + 自定义异常
declare
myexception exception;
v_name emp.ename%type;
pragma exception_init(myexception,-30000);
begin
  select ename into v_name from emp where empno = &empno;
  if v_name = 'SMITH' then
    raise myexception;
  end if;
  exception
    when myexception then   -- ora-30000
      dbms_output.put_line('SMITH不能更改');
end;

select * from emp;

　游标

-- 游标   如果你在pl/sql  操作多行数据   必须游标
-- 1定义游标  2.打开游标  3 提取数据  4关闭游标
declare
cursor cus_emp is select * from emp;
v_rowemp emp%rowtype;
v_count int;
begin
  select count(*) into v_count from emp;
  open cus_emp;
  for i in 1..v_count
  loop
    fetch cus_emp into v_rowemp;
    dbms_output.put_line(v_rowemp.empno || '   '  || v_rowemp.ename);
  end loop;  
end;


declare
cursor cus_emp is select empno,ename from emp;
type record_type is record (
  v_empno emp.empno%type,
  v_ename emp.ename%type   
);
res record_type;
v_count int;
begin
  select count(*) into v_count from emp;
  open cus_emp;
  for i in 1..v_count
  loop
    fetch cus_emp into res;
    dbms_output.put_line(res.v_empno || '   '  || res.v_ename);
  end loop;
  close cus_emp;  
end;


declare
cursor cus_emp(v_no emp.empno%type) is select empno,ename from emp where empno = v_no;
type record_type is record (
  v_empno emp.empno%type,
  v_ename emp.ename%type   
);
res record_type;
v_count int;
i int := 0;
begin
  open cus_emp(7369);
  loop
    fetch cus_emp into res;
    exit when cus_emp%notfound;
    dbms_output.put_line(res.v_empno || ' loop  '  || res.v_ename);
    
  end loop;
  close cus_emp; 
end;


  select count(*) into v_count from emp;
  open cus_emp(7369);
  while i<v_count
  loop
    fetch cus_emp into res;
    dbms_output.put_line(res.v_empno || ' while  '  || res.v_ename);
    i := i + 1;
  end loop;
  close cus_emp;