SQL server与Oracle触发器的创建与使用

SQL Server

1创建触发器

GO
BEGIN
IF (object_id('WMY', 'tr') is not null)
DROP trigger WMY
END;
GO
CREATE TRIGGER WMY
ON Student
Instead of INSERT
AS
BEGIN
    INSERT INTO Student (number,name) VALUES (1205,'角色2');
END;
--Begin 与end相当于{},是一个语句块,可有可无此处为演示所用
--ON 后面跟表明，表示作用于那个表
--ON Student下面(Instead of INSERT)可有改为(Instead of,after,for)(update,delete,Insert)

解析(以上列Insert触发器为例其他雷同)(以下先后顺序以插入表中数据的排序为例）

• 当为Instead of 时，在触发器中的SQL语句代替你文中执行的插入语句，即当你在任何地方执行一个插入语句，这条语句实际没有执行而触发器里面的语句则执行
• 当为for 时，在触发器中的SQL语句与你文中执行的插入语句都执行只是触发器中先于文中的执行
• 当为 After时 在触发器中的SQL语句与你文中执行的插入语句都执行只是触发器中晚于文中的执行(网上都这样说可简单测试时与for效果一样)

摘自网上：

1 “Instead of”触发器

• “Instead of”触发器在执行真正“插入”之前被执行。除表之外，“Instead of” 触发器也可以用于视图，用来扩展视图可以支持的更新操作。
• “Instead of”触发器会替代所要执行的SQL语句，言下之意就是所要执行SQL并不会“真正执行”

2 “After”触发器

• “After”触发器在Insert、Update或Deleted语句执行之后被触发。“After”触发器只能用于表。
• “After”触发器主要用于表在修改后（insert、update或delete操作之后），来修改其他表

SQL Server为每个触发器都创建了两个专用表:Inserted表和Deleted表。

• 这两个表由系统来维护，它们存在于内存中而不是在数据库中，可以理解为一个虚拟的表。
• 这两个表的结构总是与被该触发器作用的表的结构相同。
• 触发器执行完成后，与该触发器相关的这两个表也被删除。
• Deleted表存放由于执行Delete或Update语句而要从表中删除的所有行。
• Inserted表存放由于执行Insert或Update语句而要向表中插入的所有行。

GO
INSERT INTO Student (number,name) VALUES (1807,'角色');

深度解析使用序列以及Inserted表

USE [OSMP]
BEGIN
IF EXISTS (SELECT * FROM sysobjects WHERE name = 'Person')
AND NOT EXISTS (select * from Person) --这条语句的意思是当表存在并且不为空是执行下面的语句 ，and对应&&，or 对应||
DROP table Person
END
GO
CREATE TABLE Person
(
    num int,
    S_score int,
    S_name NVARCHAR(64),
    primary key (num)
)
BEGIN
IF EXISTS (SELECT * FROM sysobjects WHERE name = 'Student')
AND NOT EXISTS (select * from Student) 
DROP table Student
END
GO
CREATE TABLE Student
(
    score int,
    name NVARCHAR(64),
    primary key (name)
)
--创建序列
BEGIN
IF EXISTS (SELECT * FROM sysobjects WHERE name = 'Student_SEQ')
DROP SEQUENCE Student_SEQ
END
CREATE SEQUENCE Student_SEQ
MINVALUE 1
MAXVALUE 999999999999
START WITH 1
INCREMENT BY 1
CACHE 20;

GO
BEGIN
IF (object_id('WMY', 'tr') is not null)
DROP trigger WMY
END;
GO
CREATE TRIGGER WMY
ON Student
instead of INSERT
AS
BEGIN

    Insert into Person (num,S_score,S_name)select next value for Student_SEQ,score,name from Inserted 

    --Insert into Person (num,S_score,S_name)select next value for Student_SEQ,a.* from Inserted a --简化写法
    --Insert into Person select next value for Student_SEQ,* from Inserted

    --此处并无意思主要用于理解,执行下面的Student插入语句是，数据库维护了一个与Student数据结构一样的表Inserted,
    --这里利用这个表和序列值来为Person做插入，而实际上没有执行Student插入，如果想要Student也执行把Instead of 改为for或after
END;
GO
Insert into Student(score,name) values('1','m');

插曲获取序列的当前值

GO
SELECT current_value FROM sys.sequences WHERE name = 'Student_SEQ'

sql server定义变量以及变量赋值

DECLARE @index VARCHAR(20),@Orderindex VARCHAR(20);
select @index=next value for ENTITY_SEQ;
select @Orderindex= 'R_'+rtrim(ltrim(right(cast('00000000'+rtrim(cast(@index as int)) as varchar(20)),10)))

　　

Oracle 触发器与SQL server类似，在此只显示代码

new是新插入的数据，old是原来的数据

insert只会有new，代表着要插入的新记录

delete只会有old，代表着要删除的记录

update由于执行的是先删除旧的记录，再插入新的记录，因此new和old都会有，且含义与上面的相同

注：update触发器，可根据具体需求选择记录旧记录还是新记录。

  *这两个变量只有在使用了关键字 "FOR EACH ROW"时才存在.且update语句两个都有,而insert只有:new ,delect 只有:old;

  * for each row 指定触发器每行触发一次

BEGIN
    EXECUTE IMMEDIATE 'DROP TABLE Person';
    EXCEPTION WHEN OTHERS THEN NULL;
END;

CREATE TABLE Person
(
    num        INTEGER
    S_score   INTEGER,
    S_name     NVARCHAR2(64),
    primary key (num)
)
BEGIN
    EXECUTE IMMEDIATE 'DROP TABLE Student';
    EXCEPTION WHEN OTHERS THEN NULL;
END;

CREATE TABLE Student
(
    score   INTEGER,
    name     NVARCHAR2(64),
    primary key (name)
)
--创建序列
BEGIN
    EXECUTE IMMEDIATE 'DROP SEQUENCE Student_SEQ';
    EXCEPTION WHEN OTHERS THEN NULL;
END;
CREATE SEQUENCE Student_SEQ
MINVALUE 1
MAXVALUE 999999999999999999999999999
START WITH 1
INCREMENT BY 1
CACHE 20;

CREATE OR REPLACE TRIGGER TR_INST_DEVICE
BEFORE INSERT ON M_DEVICEENTITY
FOR EACH ROW

BEGIN
    select Student_SEQ.NEXTVAL into :new.num from dual;
    --select 'A' || trim(to_char(:new.num, '00000000')) into :new.score from dual;
    --这个两语句作用并无练习，第一个取出序列的下一个值插入new表中(new表类似SQL server 中的Inserted)
    --更改score的标示发以A_0000001为样式，这个语句只做参考在此处无用也运行不了(因为表的字段类型）
END;

GO
 Insert into Student(score,name) values('1','m')

　Intert into Select值与表组合的表示方法

Insert into Person(n, num, name) select next value for ENTITY_SEQ,number,name from Student where number=114;
--next value for ENTITY_SEQ序列与select字段组合添加
Insert into Person(n, num, name) select cast(100 as int),number,name from Student where number=114;
--cast(100 as int)值与字段组合添加

　C# 中Oracle分页写法　end，start为传入的数值，

 cmd.CommandText = @"SELECT * FROM (SELECT ROWNUM AS rowno, t.*  FROM  '+tablename +' t
                 WHERE ROWNUM <=  '" + end + "') table_alias  WHERE table_alias.rowno >=  '" + start + "'";

　

   cmd.CommandText = @"select * from M_ORDERHANDLE where ORDERINDEX  = '" + orderindex + "'";  

　　

SELECT *
  FROM (SELECT ROWNUM AS rowno, t.*
          FROM emp t
         WHERE hire_date BETWEEN TO_DATE ('20060501', 'yyyymmdd')
                             AND TO_DATE ('20060731', 'yyyymmdd')
           AND ROWNUM <= 20) table_alias
 WHERE table_alias.rowno >= 10;

　　

SELECT * FROM (SELECT * FROM M_ALARM ) WHERE ROWNUM <=500  ORDER BY ROWNUM Desc;

　　

--Oracle环境下的时间比对语句
SELECT * FROM M_WORKORDER where CREATETIME  >= to_date('2015/03/23','yyyy-mm-dd hh24:mi:ss') and
 CREATETIME <= to_date('2016/03/23','yyyy-mm-dd hh24:mi:ss')



SELECT * FROM M_WORKORDER where to_char(CREATETIME, 'yyyy-mm-dd hh24:mi:ss') >= '2015-03-01 00:00:00' and
 to_char(CREATETIME, 'yyyy-mm-dd hh24:mi:ss') <= '2016-04-05 00:00:00'
--注意时间格式转换为一致

　　

//Oracle多表连接查询
string sql =  @"SELECT W.*, D.*, AH.*, A.ALARMDESCRIPTION, A.DETECTTIME, A.ALARMPHENOMENON, A.ENTITYTYPE
                            FROM  M_WORKORDER W, M_ALARM A,
                            (SELECT * FROM
                                (SELECT ROW_NUMBER() OVER (PARTITION BY H.ALARMINDEX ORDER BY H.HANDLETIME DESC) N,
                                H.* FROM M_ALARMHANDLE H)
                            WHERE N = 1) AH,
                            (SELECT * FROM M_CONFIGITEMRELATION C, M_BUSINESSENTITY B 
                            WHERE C.TARGETINDEX = B.ENTITYINDEX AND C.GROUPTYPE = 1) D 
                            WHERE W.ALARMINDEX = D.SOURCEINDEX(+) AND W.ALARMINDEX = AH.ALARMINDEX(+) AND
                            A.ALARMINDEX = W.ALARMINDEX AND 
to_char(CREATETIME, 'yyyy-mm-dd') >= '" + Convert.ToDateTime(StartTime).ToString("yyyy-MM-dd") + "' and 
to_char(CREATETIME, 'yyyy-mm-dd') <= '" + Convert.ToDateTime(EndTime).ToString("yyyy-MM-dd") + "' and rownum<20";

　　注意 (+)左右边对应的是左右连接，

//SQL server 对应的多表连接查询
string sql = @"SELECT W.*, D.*, AH.*, A.ALARMDESCRIPTION, A.DETECTTIME, A.ALARMPHENOMENON, A.ENTITYTYPE
                            FROM  M_ALARM A,M_WORKORDER W LEFT JOIN
                            (SELECT * FROM 
                              (SELECT ROW_NUMBER() OVER (PARTITION BY H.ALARMINDEX ORDER BY H.HANDLETIME DESC) N,
                                H.* FROM M_ALARMHANDLE H) M
                            WHERE M.N=1)AH on W.ALARMINDEX = AH.ALARMINDEX  
							   LEFT JOIN
                            (SELECT * FROM M_CONFIGITEMRELATION C, M_BUSINESSENTITY B 
                            WHERE C.TARGETINDEX = B.ENTITYINDEX AND C.GROUPTYPE = 1)D ON W.ALARMINDEX = D.SOURCEINDEX
                            WHERE A.ALARMINDEX = W.ALARMINDEX and CONVERT(varchar(100),w.createtime, 20) >= '" +
   Convert.ToDateTime(StartTime).ToString("yyyy-MM-dd") + "' and
   CONVERT(varchar(100),w.createtime, 20) <= '" + Convert.ToDateTime(EndTime).ToString("yyyy-MM-dd") + "'";

SQL server Select Into用法详解

http://wenku.baidu.com/link?url=I7DrdMzq7-ONDePwrmkHJjofYiS1KL6kyT9pzVcLvz4g0eSxoKH0lvfJYtEcJhxgsfVrB9uHokJRHjHC43kj6sxN5bVCQUoSh-B-IB5tQHC

SQL server 触发器里面判断是什么引发的触发

http://www.2cto.com/database/201308/238647.html