以下内容只是部分原创,仅是之前收集到的知识。只做记录避免遗忘,具体出处已遗忘。
一、游标结构
总是遗忘游标的结构
declare PeriodDataCursor cursor
for
select ID , ClassTime from @temptable order by [ClassTime] desc
open PeriodDataCursor
fetch next from PeriodDataCursor into @ID , @firstClsTime
while(@@FETCH_STATUS=0)
begin
if((select top 1 1 from Mall_EverydayValue where Summary='-初始化' and InPeriod=@ID )=1)
begin
select 1 ;
end
fetch next from PeriodDataCursor into @ID , @firstClsTime
end
close PeriodDataCursor
deallocate PeriodDataCursor
end
二、级联删除,更新
/*
drop table test_sub
drop table test_main
*/
-- 创建测试主表. ID 是主键.
CREATE TABLE test_main
(
id INT NOT NULL,
value VARCHAR(10), PRIMARY KEY(id)
);
-- 创建测试子表.
CREATE TABLE test_sub
( id INT NOT NULL,
main_id INT , value VARCHAR(10), PRIMARY KEY(id)
);
--创建外键,使用 ON DELETE CASCADE 选项,删除主表的时候,同时删除子表
-- ON UPDATE CASCADE 级联更新
ALTER TABLE test_sub ADD CONSTRAINT main_id_cons FOREIGN KEY (main_id) REFERENCES test_main(id)
ON DELETE CASCADE ON UPDATE CASCADE ;
-- 插入测试主表数据.
INSERT INTO test_main(id, value) VALUES (1, 'ONE');
INSERT INTO test_main(id, value) VALUES (2, 'TWO');
-- 插入测试子表数据.
INSERT INTO test_sub(id, main_id, value) VALUES (1, 1, 'ONEONE');
INSERT INTO test_sub(id, main_id, value) VALUES (2, 2, 'TWOTWO');
--执行删除:
DELETE FROM TEST_MAIN WHERE ID = 1;
-- 执行更新:
update TEST_MAIN set id=5 from TEST_MAIN where id=2 ;
-- DELETE FROM test_sub WHERE ID = 1;
--最后:
SELECT * FROM TEST_MAIN;
SELECT * FROM test_sub;
--结果子表中就只有ID=5的记录,也就说明级联删除成功和更新成功。
三、获取该所有外键
SELECT 主键列ID=b.rkey
,主键列名=(SELECT name FROM syscolumns WHERE colid=b.rkey AND id=b.rkeyid)
,外键表ID=b.fkeyid
,外键表名称=object_name(b.fkeyid)
,外键列ID=b.fkey
,外键列名=(SELECT name FROM syscolumns WHERE colid=b.fkey AND id=b.fkeyid)
,级联更新=ObjectProperty(a.id,'CnstIsUpdateCascade')
,级联删除=ObjectProperty(a.id,'CnstIsDeleteCascade')
FROM sysobjects a
join sysforeignkeys b on a.id=b.constid
join sysobjects c on a.parent_obj=c.id
where a.xtype='f' AND c.xtype='U'
and object_name(b.rkeyid)='TEST_MAIN'