sql在insert时判断有无唯一性冲突,存在相同主键或唯一索引,则不创建 INSERT INTO table(field1, field2, fieldn) SELECT 'field1', 'field2', 'fieldn' FROM DUAL WHERE NOT EXISTS(SELECT field FROM table WHERE field = ?)
我们在做sql更新时,为防止sql重复执行报错,需要对所需要执行的对象进行判断是否存在: 常用判断脚本如下: 判断视图是否存在 IF object_id('viewname') IS not NULL begin --操作 --drop view viewname end 判断表是否存在 IF object_id('tablename') IS NULL BEGIN --操作 END 判断列是否存在 FROM dbo.syscolumns WHERE [name]='columnname' AN
http://poj.org/problem?id=1679 Description Given a connected undirected graph, tell if its minimum spanning tree is unique. Definition 1 (Spanning Tree): Consider a connected, undirected graph G = (V, E). A spanning tree of G is a subgraph of G, say
题意:给出n个字符,m对关系,让你输出三种情况: 1.若到第k行时,能判断出唯一的拓扑序列,则输出: Sorted sequence determined after k relations: 序列 2.若到第k行,出现环,则输出: Inconsistency found after k relations. 3.若直到m行后,仍判断不出唯一的拓扑序列,则输出: Sorted sequence cannot be deter
sql语句判断方法之一CASE语句用法总结 背景: Case具有两种格式.简单Case函数和Case搜索函数. --简单Case函数 CASE sex WHEN '1' THEN '男' WHEN '2' THEN '女' ELSE '其他' END --Case搜索函数 CASE WHEN sex = '1' THEN '男' WHEN sex = '2' THEN '女' ELSE '其他' END 这两种方式,可以实现相同的功能.简单Case函数的写法相对比较简洁,但是和Case搜索函数相
1 判断数据库是否存在Sql代码 if exists (select * from sys.databases where name = ’数据库名’) drop database [数据库名] if exists (select * from sys.databases where name = ’数据库名’) drop database [数据库名]2 判断表是否存在Sql代码 if exists (select * from sysobjects where id = objec
使用SQL中的循环,可以实现许多我们需要的操作,比如SQL更新操作.下面就为您介绍使用游标循环进行SQL更新插入的SQL语句写法,希望对您深入学习SQL更新有所帮助. --开始事务 BEGIN TRAN --不显示计数信息 SET NOCOUNT ON DECLARE @ProjNo varchar(50),@CusNo varchar(50) --声明游标 DECLARE CRMPSContact_cursor CURSOR FOR SELECT ProjNo FROM CRMPSContac
-- SQL SERVER 判断是否存在某个触发器.储存过程 -- 判断储存过程,如果存在则删除IF (EXISTS(SELECT * FROM sysobjects WHERE name='procedurename' AND type='P')) DROP PROCEDURE procedurename -- 判断触发器,如果存在则删除IF (EXISTS(SELECT * FROM sysobjects WHERE id=object_id(N'[dbo].[triggername]')
题目链接: http://poj.org/problem?id=1679 Description Given a connected undirected graph, tell if its minimum spanning tree is unique. Definition 1 (Spanning Tree): Consider a connected, undirected graph G = (V, E). A spanning tree of G is a subgraph of G
题意:给出n个点,m条边,要你判断最小生成树是否唯一. 思路:先做一次最小生成树操作,标记选择了的边,然后枚举已经被标记了的边,判断剩下的边组成的最小生成树是否与前面的相等,相等,则不唯一,否则唯一...... #include<iostream> #include<cstdio> #include<cstring> #include<algorithm> using namespace std; struct node { int v1,v2; int d
题目链接 Description Given a connected undirected graph, tell if its minimum spanning tree is unique. Definition 1 (Spanning Tree): Consider a connected, undirected graph G = (V, E). A spanning tree of G is a subgraph of G, say T = (V', E'), with the fol
摘自: http://www.111cn.net/database/mssqlserver/39107.htm sql判断存储过程是否存在 判断数据库教程是否存在 Sql代码 if exists (select * from sys.databases where name = ’数据库名’) drop database [数据库名] if exists (select * from sys.databases where name = ’数据库名’) drop database [数据库名]
1. sql语句判断是否为数字.字母.中文 select ascii(字段) 数字:48-57字母:65-123汉字:123+ 如,要删除某个全为数字的字段 DELETE FROM table WHERE ascii(name) between 48 and 57 2. 一.包含中文字符 select * from 表名 where 列名 like '%[吖-座]%' 二.包含英文字符 select * from 表名 where 列名 like '%[a-z]%' 三.包含纯数字 selec
sql语句判断方法之一 selectcase when t.bk1='on' then 1else 0 end as 基础 ,case when t.bk2='on' then 1else 0 end as 法规 ,case when t.bk3='on' then 1else 0 end as 电算化 from info t select t.bk1,t.bk2,t.bk3,case when t.bk1='on' then 1else 0 end +case when t.bk2='