blocks|key|478743|text|如果您只想将"“作为空字符串进行匹配|type|unstyled|depth|inlineStyleRanges|entityRanges|data|478744|WHERE+DATALENGTH(COLUMN)+>+0+|code-block|syntax|javascript|478745|如果要将完全由空格组成的任何字符串计为空|478746|WHERE+COLUMN+<>+''+|478747|当在WHERE子句中使用时，这两种方法都不会返回NULL值。因为对于这些，NULL将评估为UNKNOWN，而不是TRUE。|offset|length|style|CODE|478748|CREATE+TABLE+T+
++(+
+++++C+VARCHAR(10)+
++);+

INSERT+INTO+T+
VALUES++++++('A'),+
++++++++++++(''),
++++++++++++('++++'),+
++++++++++++(NULL);+

SELECT+*+
FROM+++T+
WHERE++C+<>+''|478749|仅返回单行A。也就是说，包含NULL、空字符串或完全由空格组成的字符串的行都将被此查询排除。|478750|SQL+Fiddle|478751|entityMap|0|LINK|mutability|MUTABLE|url|http://www.sqlfiddle.com/#!3/3d933/1^0|0|0|0|0|2|5|O|4|11|4|19|7|1K|4|0|0|5|1|E|4|0|0|A|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|15|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|16|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|17|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|18|8|@$M|19|N|1A|O|P]|$M|1B|N|1C|O|P]|$M|1D|N|1E|O|P]|$M|1F|N|1G|O|P]|$M|1H|N|1I|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|D|7|1J|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|1K|8|@$M|1L|N|1M|O|P]|$M|1N|N|1O|O|P]]|9|@]|A|$]]|$1|U|3|V|5|6|7|1P|8|@]|9|@$M|1Q|N|1R|1|1S]]|A|$]]|$1|W|3|-4|5|6|7|1T|8|@]|9|@]|A|$]]]|X|$Y|$5|Z|10|11|A|$12|13]]]]

If you only want to match "" as an empty string

<pre><code>WHERE DATALENGTH(COLUMN) &gt; 0 
</code></pre>

If you want to count any string consisting entirely of spaces as empty

<pre><code>WHERE COLUMN &lt;&gt; '' 
</code></pre>

Both of these will not return <code>NULL</code> values when used in a <code>WHERE</code> clause. As <code>NULL</code> will evaluate as <code>UNKNOWN</code> for these rather than <code>TRUE</code>.

<pre><code>CREATE TABLE T 
 ( 
 C VARCHAR(10) 
 ); 

INSERT INTO T 
VALUES ('A'), 
 (''),
 (' '), 
 (NULL); 

SELECT * 
FROM T 
WHERE C &lt;&gt; ''
</code></pre>

Returns just the single row <code>A</code>. I.e. The rows with <code>NULL</code> or an empty string or a string consisting entirely of spaces are all excluded by this query.

<a href="http://www.sqlfiddle.com/#!3/3d933/1">SQL Fiddle</a>

blocks|key|694853|text|Coalesce会将空值合并为默认值：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|694854|COALESCE+(fieldName,+'')+<>+''|code-block|syntax|javascript|694855|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|$]]

Coalesce will fold nulls into a default:

<pre><code>COALESCE (fieldName, '') &lt;&gt; ''
</code></pre>

blocks|key|478843|text|这样做的一种索引友好的方法是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|478844|where+(field+is+not+null+and+field+<>+'')|code-block|syntax|javascript|478845|如果行不是很多，或者这个字段没有索引，可以使用：|478846|+where+isnull(field,'')+<>+''|478847|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

An index friendly way of doing this is:

<pre><code>where (field is not null and field &lt;&gt; '')
</code></pre>

If there aren't many rows or this field isn't indexed, you can use:

<pre><code> where isnull(field,'') &lt;&gt; ''
</code></pre>

blocks|key|478885|text|只需检查:+where+value+>+'‘--+not+null和not+empty|type|unstyled|depth|inlineStyleRanges|entityRanges|data|478886|--+COLUMN+CONTAINS+A+VALUE+(ie+string+not+null+and+not+empty)+:
--+(note:+"<>"+gives+a+different+result+than+">")
select+iif(null++++>+'',+'true',+'false');+--+false+(null)
select+iif(''++++++>+'',+'true',+'false');+--+false+(empty+string)
select+iif('+'+++++>+'',+'true',+'false');+--+false+(space)
select+iif('++++'++>+'',+'true',+'false');+--+false+(tab)
select+iif('
'++++++++++++++++++>+'',+'true',+'false');+--+false+(newline)
select+iif('xxx'+++>+'',+'true',+'false');+--+true
--
--
--+NOTE+-+test+that+tab+and+newline+is+processed+as+expected:
select+'x+++x'+--+tab
select+'x

x'+--+newline|code-block|syntax|javascript|478887|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|$]]

Just check: where value > '' -- not null and not empty

<pre><code>-- COLUMN CONTAINS A VALUE (ie string not null and not empty) :
-- (note: "&lt;&gt;" gives a different result than "&gt;")
select iif(null &gt; '', 'true', 'false'); -- false (null)
select iif('' &gt; '', 'true', 'false'); -- false (empty string)
select iif(' ' &gt; '', 'true', 'false'); -- false (space)
select iif(' ' &gt; '', 'true', 'false'); -- false (tab)
select iif('
' &gt; '', 'true', 'false'); -- false (newline)
select iif('xxx' &gt; '', 'true', 'false'); -- true
--
--
-- NOTE - test that tab and newline is processed as expected:
select 'x x' -- tab
select 'x

x' -- newline
</code></pre>

blocks|key|694976|text|以基本的方式|type|unstyled|depth|inlineStyleRanges|entityRanges|data|694977|SELECT+*
FROM+[TableName]
WHERE+column_name!=''+AND+column_name+IS+NOT+NULL|code-block|syntax|javascript|694978|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|$]]

in basic way

<pre><code>SELECT *
FROM [TableName]
WHERE column_name!='' AND column_name IS NOT NULL
</code></pre>

blocks|key|478977|text|您可以使用其中任何一个来检查null、空格和空字符串。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|478978|WHERE+COLUMN+<>+''+

WHERE+LEN(COLUMN)+>+0

WHERE+NULLIF(LTRIM(RTRIM(COLUMN)),+'')+IS+NOT+NULL|code-block|syntax|javascript|478979|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 either one of these to check null, whitespace and empty strings.

<pre><code>WHERE COLUMN &lt;&gt; '' 

WHERE LEN(COLUMN) &gt; 0

WHERE NULLIF(LTRIM(RTRIM(COLUMN)), '') IS NOT NULL
</code></pre>

blocks|key|479057|text|由于某种原因，我的空值的数据长度是8。这就是为什么上面提到的似乎都不起作用。如果您遇到同样的问题，请使用以下代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|479058|--Check+the+length+of+your+NULL+values
SELECT+DATALENGTH(COLUMN)+as+length_column
FROM+your_table

--Filter+the+length+of+your+NULL+values+(8+is+used+as+example)
WHERE+DATALENGTH(COLUMN)+>+8|code-block|syntax|javascript|479059|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|$]]

For some kind of reason my NULL values where of data length 8. That is why none of the abovementioned seemed to work. If you encounter the same problem, use the following code:
<pre><code>--Check the length of your NULL values
SELECT DATALENGTH(COLUMN) as length_column
FROM your_table

--Filter the length of your NULL values (8 is used as example)
WHERE DATALENGTH(COLUMN) &gt; 8
</code></pre>

blocks|key|479100|text|下面这句话对我很有效。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|479101|$sql+=+"SELECT+table_name+FROM+product_reviews+WHERE+title+>+'0'++
and++product='Product+name'";|code-block|syntax|javascript|479102|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|$]]

The below statement worked for me.
<pre><code>$sql = &quot;SELECT table_name FROM product_reviews WHERE title &gt; '0' 
and product='Product name'&quot;;

</code></pre>

How can we check in a SQL Server <code>WHERE</code> condition whether the column is not null and not the empty string (<code>''</code>)?

How to check for Is not Null And Is not Empty string in SQL server?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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如何在SQL Server WHERE条件中检查列是否不为null且不是空字符串('')？

问如何检查SQL server中的Is not Null和非空字符串？
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问如何检查SQL server中的Is not Null和非空字符串？EN