在SQL中建立外键约束,可以级联查询表中的数据,在C#代码生成器中,也能根据外键关系生成相应的外键表数据模型。外键也可防止删除有外键关系的记录,一定程度上保护了数据的安全性。步骤:1、要建立外键关系,首先要保证用来建立外键关系的列具有唯一性,即具有 UNIQUE 约束通常是某表的主键作为另外一个表....
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数据库 时间:
2014-06-27 21:47:54
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284
Given n, how many structurally unique BST's (binary search trees) that store values 1...n?For example,Given n = 3, there are a total of 5 unique BST's...
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其他好文 时间:
2014-06-27 18:22:07
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191
Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.
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其他好文 时间:
2014-06-27 12:52:03
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213
Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longes...
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其他好文 时间:
2014-06-27 12:46:45
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238
Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of ...
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其他好文 时间:
2014-06-27 12:27:28
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169
Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array whic...
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其他好文 时间:
2014-06-27 12:13:18
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207
Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.
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其他好文 时间:
2014-06-27 12:11:50
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337
Given a set of candidate numbers (C) and a target number (T), find all unique combinations inCwhere the candidate numbers sums toT.Thesamerepeated num...
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其他好文 时间:
2014-06-26 15:50:35
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176
Given a collection of candidate numbers (C) and a target number (T), find all unique combinations inCwhere the candidate numbers sums toT.Each number ...
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其他好文 时间:
2014-06-26 15:45:49
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163
Follow up for "Unique Paths":Now consider if some obstacles are added to the grids. How many unique paths would there be?An obstacle and empty space i...
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其他好文 时间:
2014-06-25 09:17:03
阅读次数:
159