Loading... <img class=" ls-is-cached lazyloaded" title="1480776820928760.jpg" src="https://www.zsythink.net/wp-content/uploads/ueditor/php/upload/image/20161203/1480776820928760.jpg" alt="mysql.jpg" data-src="https://www.zsythink.net/wp-content/uploads/ueditor/php/upload/image/20161203/1480776820928760.jpg" style=""> 这篇文章总结了mysql中的delete语句以及update语句的基本用法,insert语句之前已经总结过,select语句将会在其他文章中单独总结。 在本博客中,”mysql”是一个系列文章,这些文章主要对mysql/mariadb的常用知识点进行了总结,每一篇博客总结的知识点有所不同,具体内容可参考mysql文章列表。 mysql文章列表直达链接:<a href="https://www.zsythink.net/archives/tag/mysql/" target="_blank" rel="noopener">mysql知识点总结</a> <h2>delete常用语句</h2> 删除数据的语句比较简单,主要是通过where子句给定删除的范围,而where子句的示例可以参考select常用语句,但是删除前请确定给定的条件没有任何问题,在不确定的情况下不要随意删除数据。 如下语句表示删除tb1中的所有数据,也就是清空tb1表,非常危险,切勿随意使用。 <div class="enlighter-default enlighter-v-standard enlighter-t-enlighter enlighter-hover enlighter-overflow-scroll"> <div class="enlighter-toolbar"> <div class="enlighter-btn enlighter-btn-raw"></div> <div class="enlighter-btn enlighter-btn-copy"></div> <div class="enlighter-btn enlighter-btn-window"></div> </div> <div class="enlighter"> <div class=""> <div><span class="enlighter-text">delete from tb1;</span></div> </div> </div> </div> 根据给定的条件删除数据,在不确定的情况下或者没有备份的情况下,请勿随意删除数据 <div class="enlighter-default enlighter-v-standard enlighter-t-enlighter enlighter-hover enlighter-overflow-scroll"> <div class="enlighter-toolbar"> <div class="enlighter-btn enlighter-btn-raw"></div> <div class="enlighter-btn enlighter-btn-copy"></div> <div class="enlighter-btn enlighter-btn-window"></div> </div> <div class="enlighter"> <div class=""> <div><span class="enlighter-text">delete from tb1 where age=</span><span class="enlighter-n1">22</span><span class="enlighter-text">;</span></div> </div> <div class=""> <div><span class="enlighter-text">delete from tb1 where name rlike </span><span class="enlighter-s0">'^t.*'</span><span class="enlighter-text">;</span></div> </div> </div> </div> 如下语句表示,从tb1表中找出age>30的数据行,然后将这些行按照age进行降序排列,排列后删除第一个。 <div class="enlighter-default enlighter-v-standard enlighter-t-enlighter enlighter-hover enlighter-overflow-scroll"> <div class="enlighter-toolbar"> <div class="enlighter-btn enlighter-btn-raw"></div> <div class="enlighter-btn enlighter-btn-copy"></div> <div class="enlighter-btn enlighter-btn-window"></div> </div> <div class="enlighter"> <div class=""> <div><span class="enlighter-text">delete from tb1 where age </span><span class="enlighter-g1">></span> <span class="enlighter-n1">30</span><span class="enlighter-text"> order by age desc limit </span><span class="enlighter-n1">1</span><span class="enlighter-text">;</span></div> </div> </div> </div> <h2>update常用语句</h2> 修改数据的语句也比较简单,主要是通过where子句给定修改的范围,而where子句的示例可以参考select常用语句,执行更新语句之前请确定给定的条件是正确的,因为不加任何条件的更新语句表示更新表中的所有字段,如果你不确定要这么做,这样是非常危险的,所以执行update语句之前,也要再三确定条件给定正确。 如下语句表示更新tb1表中所有行的age字段的值为28,这种语句比较危险,除非你确定这样做,否则切勿执行。 <div class="enlighter-default enlighter-v-standard enlighter-t-enlighter enlighter-hover enlighter-overflow-scroll"> <div class="enlighter-toolbar"> <div class="enlighter-btn enlighter-btn-raw"></div> <div class="enlighter-btn enlighter-btn-copy"></div> <div class="enlighter-btn enlighter-btn-window"></div> </div> <div class="enlighter"> <div class=""> <div><span class="enlighter-text">update tb1 set age = </span><span class="enlighter-n1">28</span><span class="enlighter-text">;</span></div> </div> </div> </div> 如下语句表示将tb1表中id号为13的行中的name字段的值改为luffy. <div class="enlighter-default enlighter-v-standard enlighter-t-enlighter enlighter-hover enlighter-overflow-scroll"> <div class="enlighter-toolbar"> <div class="enlighter-btn enlighter-btn-raw"></div> <div class="enlighter-btn enlighter-btn-copy"></div> <div class="enlighter-btn enlighter-btn-window"></div> </div> <div class="enlighter"> <div class=""> <div><span class="enlighter-text">update tb1 set name=</span><span class="enlighter-s0">'luffy'</span><span class="enlighter-text"> where id=</span><span class="enlighter-n1">13</span><span class="enlighter-text">;</span></div> </div> </div> </div> 如下语句同上,只是一次修改了多个字段的值。 <div class="enlighter-default enlighter-v-standard enlighter-t-enlighter enlighter-hover enlighter-overflow-scroll"> <div class="enlighter-toolbar"> <div class="enlighter-btn enlighter-btn-raw"></div> <div class="enlighter-btn enlighter-btn-copy"></div> <div class="enlighter-btn enlighter-btn-window"></div> </div> <div class="enlighter"> <div class=""> <div><span class="enlighter-text">update tb1 set name=</span><span class="enlighter-s0">'luffy'</span><span class="enlighter-text">,age=</span><span class="enlighter-n1">25</span><span class="enlighter-text"> where id=</span><span class="enlighter-n1">13</span><span class="enlighter-text">;</span></div> <div>转载自朱双印日志https://www.zsythink.net/archives/1044</div> </div> </div> </div> Last modification:May 29, 2024 © Allow specification reprint Like 如果觉得我的文章对你有用,请随意赞赏