Oracle SQL学习笔记

select LEVEL, childId, parentId from TreeTable start with parentId=0 connect by parentId=prior childId

select LEVEL, t.TYPE_ID, t.TYPE_PARENTID from gwd_type_of_doc t start with t.type_parentid=0 connect by t.type_parentid=prior t.type_id order siblings by sortno asc

 

CREATE OR REPLACE TRIGGER "DatabaseName"."TriggerName"
BEFORE INSERT ON "TableName"
FOR EACH ROW
WHEN (new.KeyID is null)
BEGIN
select seqenceName.nextval into :new.KeyID from dual;
END;

待续...

 

 

-- 表
create table test (names varchar2(12),
                    dates date,
                    num    int,
                    dou    double);
-- 视图
create or replace view vi_test as
select * from test;

-- 同义词
create or replace synonym aa
for dbusrcard001.aa;

-- 存储过程
create or replace produce dd(v_id in employee.empoy_id%type)
as
begin
   
end
dd;

-- 函数
create or replace function ee(v_id in employee%rowtype) return varchar(15)
is
var_test varchar2(15);
begin
   return var_test;
exception when others then
   
end

-- 三种触发器的定义
create or replace trigger ff
alter delete
on test
for each row
declare
begin
    delete from test;
    if sql%rowcount < 0 or sql%rowcount is null then
       rais_replaction_err(-20004,"错误")
    end if
end

create or replace trigger gg
alter insert
on test
for each row
declare
begin
    if :old.names = :new.names then
       raise_replaction_err(-2003,"编码重复");
    end if
end

create or replace trigger hh
for update
on test
for each row
declare
begin
   if updating then
      if :old.names <> :new.names then
reaise_replaction_err(-2002,"关键字不能修改")
      end if
   end if
end

-- 定义游标
declare
    cursor aa is
       select names,num from test;
begin
    for bb in aa
    loop
         if bb.names = "ORACLE" then
        
         end if
    end loop;
   
end

-- 速度优化，前一语句不后一语句的速度快几十倍
select names,dates
from test,b
where test.names = b.names(+) and
       b.names is null and
       b.dates > date('2003-01-01','yyyy-mm-dd')

select names,dates
from test
where names not in ( select names
                        from b
                       where dates > to_date('2003-01-01','yyyy-mm-dd'))
                       

-- 查找重复记录
select names,num
from test
where rowid != (select max(rowid)
                  from test b
                 where b.names = test.names and
                       b.num = test.num)

-- 查找表TEST中时间最新的前10条记录
select * from (select * from test order by dates desc) where rownum < 11

-- 序列号的产生
create sequence row_id
minvalue 1
maxvalue 9999999999999999999999
start with 1
increment by 1

insert into test values(row_id.nextval,....)