blocks|key|108452|text|要在SQL2.0+(no+LINQ)中做到这一点，例如，对于.NET+-+ReportingServices，而不必为其编写函数：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|108453|VB.NET|108454|Dim+a+As+String+=+"",+b+As+String+=+"b",+c+As+String+=+"",+d+As+String+=+"d",+e+As+String+=+""
Dim+lala+As+String+=+String.Join("+/+",+String.Join(vbBack,+New+String()+{a,+b,+c,+d,+e}).Split(New+Char()+{ControlChars.Back},+System.StringSplitOptions.RemoveEmptyEntries))

System.Console.WriteLine(lala)|code-block|syntax|javascript|108455|C#+(针对那些从谷歌登陆但没有搜索VB.NET的用户)|108456|string+a+=+"",+b+=+"b",+c+=+"",+d+=+"d",+e+=+"";
string+lala+=+string.Join("+/+",
++++string.Join("\u0008",+
++++++++new+string[]+{+a,+b,+c,+d,+e+}
++++).Split(new+char[]+{+'\u0008'+},+System.StringSplitOptions.RemoveEmptyEntries)
);

System.Console.WriteLine(lala);|108457|这假设字符串中没有出现字符退格键(通常应该是真的，因为您不能简单地通过键盘输入该字符)。|108458|此外，如果您从数据库中获取值，则会更加简单，因为您可以直接在SQL中执行此操作：|108459|PostgreSQL和MySQL：|108460|SELECT+
++++concat_ws('+/+'
++++++++,+NULLIF(searchTerm1,+'')
++++++++,+NULLIF(searchTerm2,+'')
++++++++,+NULLIF(searchTerm3,+'')
++++++++,+NULLIF(searchTerm4,+'')
++++)+AS+RPT_SearchTerms;+|108461|即使使用光荣的MS-SQL-Server，这也是可能的(PS:这是讽刺)：|108462|DECLARE+@in_SearchTerm1+nvarchar(100)+
DECLARE+@in_SearchTerm2+nvarchar(100)+
DECLARE+@in_SearchTerm3+nvarchar(100)+
DECLARE+@in_SearchTerm4+nvarchar(100)+

SET+@in_SearchTerm1+=+N'a'
SET+@in_SearchTerm2+=+N''
SET+@in_SearchTerm3+=+N'c'
SET+@in_SearchTerm4+=+N''

SELECT+
++++COALESCE
++++(
++++++++STUFF
++++++++(
++++++++++++(
++++++++++++++++SELECT+'+/+'+%2B+RPT_SearchTerm+AS+[text()]
++++++++++++++++FROM+
++++++++++++++++(
++++++++++++++++++++++++++++++++++SELECT+NULLIF(@in_SearchTerm1,+N'')+AS+RPT_SearchTerm,+1+AS+RPT_Sort+
++++++++++++++++++++++++UNION+ALL+SELECT+NULLIF(@in_SearchTerm2,+N'')+AS+RPT_SearchTerm,+2+AS+RPT_Sort++
++++++++++++++++++++++++UNION+ALL+SELECT+NULLIF(@in_SearchTerm3,+N'')+AS+RPT_SearchTerm,+3+AS+RPT_Sort+
++++++++++++++++++++++++UNION+ALL+SELECT+NULLIF(@in_SearchTerm4,+N'')+AS+RPT_SearchTerm,+4+AS+RPT_Sort+
++++++++++++++++)+AS+tempT+
++++++++++++++++WHERE+RPT_SearchTerm+IS+NOT+NULL+
++++++++++++++++ORDER+BY+RPT_Sort+
++++++++++++++++FOR+XML+PATH(N''),+TYPE+
++++++++++++).value('.',+'nvarchar(MAX)')+
++++++++++++,1
++++++++++++,3
++++++++++++,N''
++++++++)
++++++++,N''
++++)+AS+RPT_SearchTerms+|108463|entityMap^0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|12|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|13|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|14|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|15|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|16|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|17|8|@]|9|@]|A|$]]|$1|S|3|T|5|F|7|18|8|@]|9|@]|A|$G|H]]|$1|U|3|V|5|6|7|19|8|@]|9|@]|A|$]]|$1|W|3|X|5|F|7|1A|8|@]|9|@]|A|$G|H]]|$1|Y|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|Z|$]]

To do it in .NET 2.0 (no LINQ), e.g. for SQL-Server ReportingServices without having to write a function for it:

VB.NET 

<pre><code>Dim a As String = "", b As String = "b", c As String = "", d As String = "d", e As String = ""
Dim lala As String = String.Join(" / ", String.Join(vbBack, New String() {a, b, c, d, e}).Split(New Char() {ControlChars.Back}, System.StringSplitOptions.RemoveEmptyEntries))

System.Console.WriteLine(lala)
</code></pre>

C# (for those landing from google and not searching for VB.NET)

<pre><code>string a = "", b = "b", c = "", d = "d", e = "";
string lala = string.Join(" / ",
 string.Join("\u0008", 
 new string[] { a, b, c, d, e }
 ).Split(new char[] { '\u0008' }, System.StringSplitOptions.RemoveEmptyEntries)
);

System.Console.WriteLine(lala);
</code></pre>

This assumes that the character backspace doesn't occur in your strings (should usually be true, because you can't simply enter this character by keyboard). 

Also, if you get the values from a database, then it's even simpler, since you can do it in SQL directly: 

PostgreSQL &amp; MySQL: 

<pre><code>SELECT 
 concat_ws(' / '
 , NULLIF(searchTerm1, '')
 , NULLIF(searchTerm2, '')
 , NULLIF(searchTerm3, '')
 , NULLIF(searchTerm4, '')
 ) AS RPT_SearchTerms; 
</code></pre>

And even with the glorious MS-SQL-Server it's possible (PS: that's sarcasm):

<pre><code>DECLARE @in_SearchTerm1 nvarchar(100) 
DECLARE @in_SearchTerm2 nvarchar(100) 
DECLARE @in_SearchTerm3 nvarchar(100) 
DECLARE @in_SearchTerm4 nvarchar(100) 

SET @in_SearchTerm1 = N'a'
SET @in_SearchTerm2 = N''
SET @in_SearchTerm3 = N'c'
SET @in_SearchTerm4 = N''

SELECT 
 COALESCE
 (
 STUFF
 (
 (
 SELECT ' / ' + RPT_SearchTerm AS [text()]
 FROM 
 (
 SELECT NULLIF(@in_SearchTerm1, N'') AS RPT_SearchTerm, 1 AS RPT_Sort 
 UNION ALL SELECT NULLIF(@in_SearchTerm2, N'') AS RPT_SearchTerm, 2 AS RPT_Sort 
 UNION ALL SELECT NULLIF(@in_SearchTerm3, N'') AS RPT_SearchTerm, 3 AS RPT_Sort 
 UNION ALL SELECT NULLIF(@in_SearchTerm4, N'') AS RPT_SearchTerm, 4 AS RPT_Sort 
 ) AS tempT 
 WHERE RPT_SearchTerm IS NOT NULL 
 ORDER BY RPT_Sort 
 FOR XML PATH(N''), TYPE 
 ).value('.', 'nvarchar(MAX)') 
 ,1
 ,3
 ,N''
 )
 ,N''
 ) AS RPT_SearchTerms 
</code></pre>

blocks|key|325668|text|尝试以下操作：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|325669|var+finalString+=+String.Join(",",+ExampleArrayOfObjects.Where(x+=>+!String.IsNullOrEmpty(x.TestParameter)).Select(x+=>+x.TestParameter));|code-block|syntax|javascript|325670|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|$]]

Try the following:

<pre><code>var finalString = String.Join(",", ExampleArrayOfObjects.Where(x =&gt; !String.IsNullOrEmpty(x.TestParameter)).Select(x =&gt; x.TestParameter));
</code></pre>

The VB.NET method <code>String.Join(separator, stringArray)</code> is similar to PHP's implode, but any null elements in the array are replaced with an empty string, so thatc:

<pre><code>Dim myArray() as String = { "a", null, "c" }
Console.WriteLine(String.Join(", ", myArray));
// Prints "a, , c"
</code></pre>

Is there a simple way to concatenate a set of strings with a separator that ignores empty strings? 

I don't necessarily need to use arrays or String.Join or anything else. I just need the following transformations:

<pre><code>("a", "b", "c") --&gt; "a, b, c"
("a", null, "c") --&gt; "a, c"
</code></pre>

String.Join method that ignores empty strings?

PostgreSQL

数据库

MySQL

VB.NET方法String.Join(separator, stringArray)类似于PHP的implode，但是数组中的任何空元素都被替换为空字符串，因此c：Dim myArray() as String = { "a", null, "c" }Console.WriteLine(String.Join(", ...

问忽略空字符串的String.Join方法？
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