blocks|key|1138120|text|您可以在单个where子句中使用标准的.NET布尔运算符：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1138121|MyDataSource.Where(data+=>+data.a+==+'a'+%7C%7C+data.a+==+'b')|code-block|syntax|javascript|1138122|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can use the standard .NET boolean operators in your single where clause:

<pre><code>MyDataSource.Where(data =&gt; data.a == 'a' || data.a == 'b')
</code></pre>

blocks|key|1138171|text|您可以使用与常规C#+===>+%7C%7C中相同的运算符表示"or“或”&&“表示"and”等。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1138172|var+something+=+from+s+in+mycollection
++++++++++++++++where+s.something+==+32+%7C%7C+
++++++++++++++++++++++s.somethingelse+==+45+
++++++++++++++++select+s|code-block|syntax|javascript|1138173|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You use the all the same operators as in normal C# ===> || for "or" &amp;&amp; for "and" etc.

<pre><code>var something = from s in mycollection
 where s.something == 32 || 
 s.somethingelse == 45 
 select s
</code></pre>

blocks|key|1353431|text|你当然可以在Where子句(扩展方法)中做到这一点。但是，如果需要动态构建复杂查询，则可以使用PredicateBuilder。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1353432|+var+query+=+collection.Where(+c+=>+c.A+==+1+%7C%7C+c.B+==+2+);|code-block|syntax|javascript|1353433|或者使用PredicateBuilder|1353434|+var+predicate+=+PredicateBuilder.False<Foo>();
+predicate+=+predicate.Or(+f+=>+f.A+==+1+);
+if+(allowB)
+{
++++predicate+=+predicate.Or(+f+=>+f.B+==+1+);
+}

+var+query+=+collection.Where(+predicate+);|1353435|entityMap|0|LINK|mutability|MUTABLE|url|http://www.albahari.com/nutshell/predicatebuilder.aspx^0|1B|G|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

You can certainly do it within a Where clause (extension method). If you need to build a complex query dynamically, though, you can use a <a href="http://www.albahari.com/nutshell/predicatebuilder.aspx" rel="noreferrer">PredicateBuilder</a>.

<pre><code> var query = collection.Where( c =&gt; c.A == 1 || c.B == 2 );
</code></pre>

Or using a PredicateBuilder

<pre><code> var predicate = PredicateBuilder.False&lt;Foo&gt;();
 predicate = predicate.Or( f =&gt; f.A == 1 );
 if (allowB)
 {
 predicate = predicate.Or( f =&gt; f.B == 1 );
 }

 var query = collection.Where( predicate );
</code></pre>

blocks|key|1353467|text|在.Where()调用中，使用标准的“Or”运算符%7C%7C。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1353468|var+query+=+items.Where(item+=>+(item+==+1+%7C%7C+item+==+2));|code-block|syntax|javascript|1353469|Where调用所做的全部工作就是对您想要的任何东西进行布尔比较，因此您可以使用任意多的条件逻辑来填充它。|1353470|entityMap^0|1|8|P|2|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|N|$]]

in your <code>.Where()</code> call use the standard Boolean 'Or' operator, <code>||</code>.

<pre><code>var query = items.Where(item =&gt; (item == 1 || item == 2));
</code></pre>

All the Where call does is a Boolean comparison on anything you want, so you can fill it with as much conditional logic as you wish.

blocks|key|1138343|text|给定一个现有的.net查询，你可以添加一个接受字符串数组(SearchStrings)的where子句，并检查它们中是否有匹配你正在搜索的集合中的任何对象。使用ToLower()可以确保在SQL查询中避免区分大小写。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1138344|query.Where(i+=>+SearchStrings.Any(s+=>+i.ToLower().Contains(s.ToLower()));|code-block|syntax|javascript|1138345|您可以通过将数组中的所有单词与集合的对象进行匹配来对'and‘谓词执行相同的操作。|1138346|query.Where(i+=>+SearchStrings.All(s+=>+i.ToLower().Contains(s.ToLower()));|1138347|在本例中，i关联到集合中的每个对象，s关联到SearchStrings数组中的每个字符串。|1138348|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

This is built into .net now, not sure if it previously wasn't. Given an existing Linq query you can add a where clause that takes an array of strings (SearchStrings), and check if any of them match whatever object in the collection you're search. Using ToLower() just makes sure that you avoid case sensitivity in SQL queries.

<pre><code>query.Where(i =&gt; SearchStrings.Any(s =&gt; i.ToLower().Contains(s.ToLower()));
</code></pre>

You can do the same thing for an 'and' predicate by matching all the words in the array to the collection's object.

<pre><code>query.Where(i =&gt; SearchStrings.All(s =&gt; i.ToLower().Contains(s.ToLower()));
</code></pre>

In this example i correlates to each object in a collection, and s correlates to each string in the SearchStrings array.

blocks|key|1353579|text|如果您不知道参数计数，可以使用以下命令：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1353580|样本数据|1353581|var+parameters=+new+List<string>{"a","d"};
var+sampledata+=+new+Dictionary<string,string>();
++++sampledata["a"]+=+"A";
++++sampledata["b"]+=+"B";
++++sampledata["c"]+=+"C";
++++sampledata["d"]+=+"D";|code-block|syntax|javascript|1353582|代码|1353583|var+query+=+sampledata.AsQueryable();
var+firstItemKey+=+sampledata.FirstOrDefault().Key;
var+queryresult=+sampledata.Where(x+=>+x.Key+==+firstItemKey).AsQueryable();
foreach+(var+parameter+in+parameters.Skip(1))
{
++++queryresult=queryresult.Concat(query.Where(x+=>+x.Key+==+parameter));
}
var+result+=+queryresult.ToList();|1353584|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

If you don' t know parameter count, you can use this:

Sample Data

<pre><code>var parameters= new List&lt;string&gt;{"a","d"};
var sampledata = new Dictionary&lt;string,string&gt;();
 sampledata["a"] = "A";
 sampledata["b"] = "B";
 sampledata["c"] = "C";
 sampledata["d"] = "D";
</code></pre>

Code

<pre><code>var query = sampledata.AsQueryable();
var firstItemKey = sampledata.FirstOrDefault().Key;
var queryresult= sampledata.Where(x =&gt; x.Key == firstItemKey).AsQueryable();
foreach (var parameter in parameters.Skip(1))
{
 queryresult=queryresult.Concat(query.Where(x =&gt; x.Key == parameter));
}
var result = queryresult.ToList();
</code></pre>

Is there a method in Linq where you can use to build SQL strings like "...where (a=1) OR (a=2)"?

"Or" equivalent in Linq Where() lambda expression

Linq中有没有一种方法可以用来构建像"...where (a=1) OR (a=2)“这样的SQL字符串？

问Linq Where() lambda表达式中的"Or“等效项
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