blocks|key|685272|text|MySQL不同于大多数DBMS使用%2B或%7C%7C进行连接。它使用CONCAT函数：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|685273|SELECT+CONCAT(first_name,+'+',+last_name)+AS+Name+FROM+test.student|code-block|syntax|javascript|685274|还有CONCAT_WS+(与分隔符连接)函数，它是CONCAT()的一种特殊形式|685275|SELECT+CONCAT_WS('+',+first_name,+last_name)+from+test.student|685276|也就是说，如果希望将%7C%7C视为字符串连接操作符(与CONCAT()相同)，而不是MySQL中OR的同义词，则可以设置SQL模式。|685277|entityMap|0|LINK|mutability|MUTABLE|url|https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_concat|1|https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_concat-ws^0|H|1|J|2|T|6|T|6|0|0|0|2|9|P|8|2|9|1|0|0|A|2|O|8|19|2|0^^$0|@$1|2|3|4|5|6|7|10|8|@$9|11|A|12|B|C]|$9|13|A|14|B|C]|$9|15|A|16|B|C]]|D|@$9|17|A|18|1|19]]|E|$]]|$1|F|3|G|5|H|7|1A|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1B|8|@$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]]|D|@$9|1G|A|1H|1|1I]]|E|$]]|$1|M|3|N|5|H|7|1J|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|1K|8|@$9|1L|A|1M|B|C]|$9|1N|A|1O|B|C]|$9|1P|A|1Q|B|C]]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|1R|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]|Y|$5|T|U|V|E|$W|Z]]]]

MySQL is different from most DBMSs use of <code>+</code> or <code>||</code> for concatenation. It uses the <a href="https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_concat" rel="nofollow noreferrer"><code>CONCAT</code></a> function:
<pre><code>SELECT CONCAT(first_name, ' ', last_name) AS Name FROM test.student
</code></pre>
There's also the <a href="https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_concat-ws" rel="nofollow noreferrer"><code>CONCAT_WS</code></a> (Concatenate With Separator) function, which is a special form of <code>CONCAT()</code>:
<pre><code>SELECT CONCAT_WS(' ', first_name, last_name) from test.student
</code></pre>
That said, if you want to treat <code>||</code> as a string concatenation operator (same as <code>CONCAT()</code>) rather than as a synonym for <code>OR</code> in MySQL, you can set the <a href="https://dev.mysql.com/doc/refman/8.0/en/sql-mode.html#sqlmode_pipes_as_concat" rel="nofollow noreferrer"><code>PIPES_AS_CONCAT</code></a> SQL mode.

blocks|key|901799|text|尝试：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|901800|select+concat(first_name,last_name)+as+"Name"+from+test.student|code-block|syntax|javascript|901801|或者，更好的是：|901802|select+concat(first_name,"+",last_name)+as+"Name"+from+test.student|901803|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|$]]

Try:

<pre><code>select concat(first_name,last_name) as "Name" from test.student
</code></pre>

or, better:

<pre><code>select concat(first_name," ",last_name) as "Name" from test.student
</code></pre>

blocks|key|901845|text|使用concat()函数代替%2B，如下所示：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|901846|select+concat(firstname,+lastname)+as+"Name"+from+test.student|code-block|syntax|javascript|901847|entityMap|0|LINK|mutability|MUTABLE|url|http://dev.mysql.com/doc/refman/5.1/en/string-functions.html#function_concat^0|E|1|2|8|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

Use <a href="http://dev.mysql.com/doc/refman/5.1/en/string-functions.html#function_concat">concat()</a> function instead of <code>+</code> like this:

<pre><code>select concat(firstname, lastname) as "Name" from test.student
</code></pre>

blocks|key|901862|text|在MYSQL中，这不是连接的方式。使用CONCAT函数在这里查看：http://dev.mysql.com/doc/refman/4.1/en/string-functions.html#function_concat|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|901863|entityMap|0|LINK|mutability|MUTABLE|url|http://dev.mysql.com/doc/refman/4.1/en/string-functions.html#function_concat^0|X|24|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

That's not the way to concat in MYSQL. Use the CONCAT function Have a look here: <a href="http://dev.mysql.com/doc/refman/4.1/en/string-functions.html#function_concat" rel="nofollow">http://dev.mysql.com/doc/refman/4.1/en/string-functions.html#function_concat</a>

blocks|key|901887|text|除了concat之外，您还可以使用concat_ws+(与分隔符连接)：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|901888|SELECT+CONCAT_WS('+',+first_name,+last_name)+from+test.student|901889|此函数还具有跳过null值的好处。|901890|请参阅https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_concat-ws|901891|entityMap|0|LINK|mutability|MUTABLE|url|https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_concat-ws^0|2|6|H|9|0|0|1Q|0|8|4|0|3|28|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@$9|U|A|V|B|C]|$9|W|A|X|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|11|8|@$9|12|A|13|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|14|8|@]|D|@$9|15|A|16|1|17]]|E|$]]|$1|L|3|-4|5|6|7|18|8|@]|D|@]|E|$]]]|M|$N|$5|O|P|Q|E|$R|S]]]]

Apart from <code>concat</code> you can also use <code>concat_ws</code> (concatenate with separator):
<code>SELECT CONCAT_WS(' ', first_name, last_name) from test.student</code>
This function has the added benefit of skipping <code>null</code> values.
See <a href="https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_concat-ws" rel="nofollow noreferrer">https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_concat-ws</a>

I am using MySQL and MySQL Workbench 5.2 CE. When I try to concatenate 2 columns, <code>last_name</code> and <code>first_name</code>, it doesn't work :

<pre><code>select first_name + last_name as "Name" from test.student
</code></pre>

String concatenation in MySQL

MySQL

我使用的是MySQL和MySQL Workbench 5.2CE。当我尝试连接两列，last_name和first_name时，它不起作用：select first_name + last_name as "Name" from test.student

问MySQL中的字符串连接
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