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Constraint

Constraint子句是指限制和索引相似,虽然限制也能被用于建立和另一个表的关联。用ALTERTABLE和CREATETABLE语句中的Constraint子句来建立或删除条件.Constraint子句可分为两种类型:第一种是在单一字段上创建条件;第二种是在一个以上的字段上创建条件。
  • c#数据库开发实例

    c#数据库开发实例:有很多的实例,对学习非常的有意义! 酒店管理系统源代码 医院信息管理系统源代码 图书馆管理系统源代码 财务管理系统源代码 生产管理系统源代码 人力资源管理实例程序源代码 进销存管理实例程序源代码 if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[采购订单_供货商_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[采购订单] DROP Constraint 采购订单_供货商_fk GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[采购订单历史_供货商_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[采购订单历史] DROP Constraint 采购订单历史_供货商_fk

    标签: 数据库 开发实例

    上传时间: 2013-10-30

    上传用户:392210346

  • 进销存管理实例程序源代码

    if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[采购订单_供货商_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[采购订单] DROP Constraint 采购订单_供货商_fk GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[采购订单历史_供货商_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[采购订单历史] DROP Constraint 采购订单历史_供货商_fk GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[采购合同_供货商_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[采购合同] DROP Constraint 采购合同_供货商_fk GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[进货单_供货商_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[进货单] DROP Constraint 进货单_供货商_fk

    标签: 进销 实例程序 源代码

    上传时间: 2013-11-15

    上传用户:wkxiian

  • 人力资源管理实例程序源代码

    if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK_工资发放历史表_职员基本信息表]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[工资发放历史表] DROP Constraint FK_工资发放历史表_职员基本信息表 GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK_月工资统计表_职员基本信息表]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[月工资统计表] DROP Constraint FK_月工资统计表_职员基本信息表 GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK_职员惩罚表_职员基本信息表]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[职员惩罚表] DROP Constraint FK_职员惩罚表_职员基本信息表

    标签: 人力资源 实例程序 源代码

    上传时间: 2014-11-17

    上传用户:xinzhch

  • 生产管理系统源代码

    if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[mrp物料需求计算_物料编号_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[mrp物料需求计算] DROP Constraint mrp物料需求计算_物料编号_fk GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[mrp物料需求计算结果_物料编号_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[mrp物料需求计算结果] DROP Constraint mrp物料需求计算结果_物料编号_fk GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[mrp物料需求历史_物料编号_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[mrp物料需求历史] DROP Constraint mrp物料需求历史_物料编号_fk GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[物料清单_物料编号_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[物料清单] DROP Constraint 物料清单_物料编号_fk

    标签: 生产管理 源代码

    上传时间: 2013-11-23

    上传用户:wcl168881111111

  • 财务管理系统源代码

    if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK_分录表_凭证表]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[分录表] DROP Constraint FK_分录表_凭证表 GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[本期汇总账簿_科目代码_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[本期汇总账簿] DROP Constraint 本期汇总账簿_科目代码_fk GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[本期明细账簿_科目代码_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[本期明细账簿] DROP Constraint 本期明细账簿_科目代码_fk GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[分录表_科目代码_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[分录表] DROP Constraint 分录表_科目代码_fk GO

    标签: 财务管理系统 源代码

    上传时间: 2013-11-20

    上传用户:清山绿水

  • 图书馆管理系统源代码

    if exists (select * from dbo.sysobjects where id = object_id(N\'[dbo].[图书丢失_图书编号_fk]\') and OBJECTPROPERTY(id, N\'IsForeignKey\') = 1) ALTER TABLE [dbo].[图书丢失] DROP Constraint 图书丢失_图书编号_fk GO if exists (select * from dbo.sysobjects where id = object_id(N\'[dbo].[FK_图书罚款_图书信息]\') and OBJECTPROPERTY(id, N\'IsForeignKey\') = 1) ALTER TABLE [dbo].[图书罚款] DROP Constraint FK_图书罚款_图书信息 GO if exists (select * from dbo.sysobjects where id = object_id(N\'[dbo].[图书归还_图书编号_fk]\') and OBJECTPROPERTY(id, N\'IsForeignKey\') = 1) ALTER TABLE [dbo].[图书归还] DROP Constraint 图书归还_图书编号_fk GO if exists (select * from dbo.sysobjects where id = object_id(N\'[dbo].[图书借阅_图书编号_fk]\') and OBJECTPROPERTY(id, N\'IsForeignKey\') = 1) ALTER TABLE [dbo].[图书借阅] DROP Constraint 图书借阅_图书编号_fk GO if exists (select * from dbo.sysobjects where id = object_id(N\'[dbo].[FK_图书征订_图书信息]\') and OBJECTPROPERTY(id, N\'IsForeignKey\') = 1) ALTER TABLE [dbo].[图书征订] DROP Constraint FK_图书征订_图书信息 GO if exists (select * from dbo.sysobjects where id = object_id(N\'[dbo].[图书注销_图书编号_fk]\') and OBJECTPROPERTY(id, N\'IsForeignKey\') = 1) ALTER TABLE [dbo].[图书注销] DROP Constraint 图书注销_图书编号_fk

    标签: 图书馆 管理系统 源代码

    上传时间: 2014-05-04

    上传用户:togetsomething

  • Allegro SPB V15.2 版新增功能

    15.2 已經加入了有關貫孔及銲點的Z軸延遲計算功能. 先開啟 Setup - Constraints - Electrical Constraint sets  下的 DRC 選項.  點選 Electrical Constraints dialog box 下 Options 頁面 勾選 Z-Axis delay栏. 

    标签: Allegro 15.2 SPB

    上传时间: 2013-11-12

    上传用户:Late_Li

  • 高速PCB基础理论及内存仿真技术(经典推荐)

    第一部分 信号完整性知识基础.................................................................................5第一章 高速数字电路概述.....................................................................................51.1 何为高速电路...............................................................................................51.2 高速带来的问题及设计流程剖析...............................................................61.3 相关的一些基本概念...................................................................................8第二章 传输线理论...............................................................................................122.1 分布式系统和集总电路.............................................................................122.2 传输线的RLCG 模型和电报方程...............................................................132.3 传输线的特征阻抗.....................................................................................142.3.1 特性阻抗的本质.................................................................................142.3.2 特征阻抗相关计算.............................................................................152.3.3 特性阻抗对信号完整性的影响.........................................................172.4 传输线电报方程及推导.............................................................................182.5 趋肤效应和集束效应.................................................................................232.6 信号的反射.................................................................................................252.6.1 反射机理和电报方程.........................................................................252.6.2 反射导致信号的失真问题.................................................................302.6.2.1 过冲和下冲.....................................................................................302.6.2.2 振荡:.............................................................................................312.6.3 反射的抑制和匹配.............................................................................342.6.3.1 串行匹配.........................................................................................352.6.3.1 并行匹配.........................................................................................362.6.3.3 差分线的匹配.................................................................................392.6.3.4 多负载的匹配.................................................................................41第三章 串扰的分析...............................................................................................423.1 串扰的基本概念.........................................................................................423.2 前向串扰和后向串扰.................................................................................433.3 后向串扰的反射.........................................................................................463.4 后向串扰的饱和.........................................................................................463.5 共模和差模电流对串扰的影响.................................................................483.6 连接器的串扰问题.....................................................................................513.7 串扰的具体计算.........................................................................................543.8 避免串扰的措施.........................................................................................57第四章 EMI 抑制....................................................................................................604.1 EMI/EMC 的基本概念..................................................................................604.2 EMI 的产生..................................................................................................614.2.1 电压瞬变.............................................................................................614.2.2 信号的回流.........................................................................................624.2.3 共模和差摸EMI ..................................................................................634.3 EMI 的控制..................................................................................................654.3.1 屏蔽.....................................................................................................654.3.1.1 电场屏蔽.........................................................................................654.3.1.2 磁场屏蔽.........................................................................................674.3.1.3 电磁场屏蔽.....................................................................................674.3.1.4 电磁屏蔽体和屏蔽效率.................................................................684.3.2 滤波.....................................................................................................714.3.2.1 去耦电容.........................................................................................714.3.2.3 磁性元件.........................................................................................734.3.3 接地.....................................................................................................744.4 PCB 设计中的EMI.......................................................................................754.4.1 传输线RLC 参数和EMI ........................................................................764.4.2 叠层设计抑制EMI ..............................................................................774.4.3 电容和接地过孔对回流的作用.........................................................784.4.4 布局和走线规则.................................................................................79第五章 电源完整性理论基础...............................................................................825.1 电源噪声的起因及危害.............................................................................825.2 电源阻抗设计.............................................................................................855.3 同步开关噪声分析.....................................................................................875.3.1 芯片内部开关噪声.............................................................................885.3.2 芯片外部开关噪声.............................................................................895.3.3 等效电感衡量SSN ..............................................................................905.4 旁路电容的特性和应用.............................................................................925.4.1 电容的频率特性.................................................................................935.4.3 电容的介质和封装影响.....................................................................955.4.3 电容并联特性及反谐振.....................................................................955.4.4 如何选择电容.....................................................................................975.4.5 电容的摆放及Layout ........................................................................99第六章 系统时序.................................................................................................1006.1 普通时序系统...........................................................................................1006.1.1 时序参数的确定...............................................................................1016.1.2 时序约束条件...................................................................................1063.2 高速设计的问题.......................................................................................2093.3 SPECCTRAQuest SI Expert 的组件.......................................................2103.3.1 SPECCTRAQuest Model Integrity .................................................2103.3.2 SPECCTRAQuest Floorplanner/Editor .........................................2153.3.3 Constraint Manager .......................................................................2163.3.4 SigXplorer Expert Topology Development Environment .......2233.3.5 SigNoise 仿真子系统......................................................................2253.3.6 EMControl .........................................................................................2303.3.7 SPECCTRA Expert 自动布线器.......................................................2303.4 高速设计的大致流程...............................................................................2303.4.1 拓扑结构的探索...............................................................................2313.4.2 空间解决方案的探索.......................................................................2313.4.3 使用拓扑模板驱动设计...................................................................2313.4.4 时序驱动布局...................................................................................2323.4.5 以约束条件驱动设计.......................................................................2323.4.6 设计后分析.......................................................................................233第四章 SPECCTRAQUEST SIGNAL EXPLORER 的进阶运用..........................................2344.1 SPECCTRAQuest Signal Explorer 的功能包括:................................2344.2 图形化的拓扑结构探索...........................................................................2344.3 全面的信号完整性(Signal Integrity)分析.......................................2344.4 完全兼容 IBIS 模型...............................................................................2344.5 PCB 设计前和设计的拓扑结构提取.......................................................2354.6 仿真设置顾问...........................................................................................2354.7 改变设计的管理.......................................................................................2354.8 关键技术特点...........................................................................................2364.8.1 拓扑结构探索...................................................................................2364.8.2 SigWave 波形显示器........................................................................2364.8.3 集成化的在线分析(Integration and In-process Analysis) .236第五章 部分特殊的运用...............................................................................2375.1 Script 指令的使用..................................................................................2375.2 差分信号的仿真.......................................................................................2435.3 眼图模式的使用.......................................................................................249第四部分:HYPERLYNX 仿真工具使用指南............................................................251第一章 使用LINESIM 进行前仿真.......................................................................2511.1 用LineSim 进行仿真工作的基本方法...................................................2511.2 处理信号完整性原理图的具体问题.......................................................2591.3 在LineSim 中如何对传输线进行设置...................................................2601.4 在LineSim 中模拟IC 元件.....................................................................2631.5 在LineSim 中进行串扰仿真...................................................................268第二章 使用BOARDSIM 进行后仿真......................................................................2732.1 用BOARDSIM 进行后仿真工作的基本方法...................................................2732.2 BoardSim 的进一步介绍..........................................................................2922.3 BoardSim 中的串扰仿真..........................................................................309

    标签: PCB 内存 仿真技术

    上传时间: 2013-11-07

    上传用户:aa7821634

  • ABAQUS is a general purpose finite element analysis program which is widely used to analyses mechani

    ABAQUS is a general purpose finite element analysis program which is widely used to analyses mechanical, structure and civil engineering problems. Abaqus has some special feature for analysing fracture mechanics problems, and therefore it is a main tools for the FE-analysis in the Fracture Group at the Mechanical Engineering at Glasgow Universtity. The software which can transfer data from Abaqus into a Matlab readable environment has been developed as a part of a research program in Constraint Estimation in Fracture Mechanics. This research program was funded by a grant from the Defence Research Agency through Prof. J. Sumpter.

    标签: analysis analyses general element

    上传时间: 2015-05-13

    上传用户:xfbs821

  • This class implements the same API as the Java 1.3 java.util.TimerTask. * Note that a TimerTask ca

    This class implements the same API as the Java 1.3 java.util.TimerTask. * Note that a TimerTask can only be scheduled on one Timer at a time, but * that this implementation does not enforce that Constraint.

    标签: TimerTask implements the class

    上传时间: 2015-06-10

    上传用户:无聊来刷下