SQL查询替换基于通配符的字符串

本文介绍了SQL查询替换基于通配符的字符串的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！问题描述

我想在我的WP数据库上运行这种类型的查询，以删除所有id ="more-"的跨度实例:

UPDATE wp_posts SET post_content = REPLACE ( post_content, '', '');

但是在我的示例中，"more-"后面的数字是一个变量.如何使用通配符之类的方式编写此查询:span id ="more-*.

谢谢

解决方案

在MySQL 8.0及更高版本中，您可以使用 REGEX_REPLACE() 函数.在缺少相同内容中，可以完成一些复杂的字符串操作.这基于您的确认，则该子字符串在一个值中仅出现一次.

REPLACE() 不对通配符，模式，正则表达式等有任何支持.它仅将给定的 fixed 子字符串替换为另一个 fixed 子字符串，且字符串较大.

相反，我们可以尝试提取post_content的某些部分.我们将使用 Substring_Index() 函数.同样，我们将提取'">'部分后面的子字符串.

现在，我们只需 Concat() 这些部分以获取所需的post_content.您可以在此处找到各种String函数的详细信息: dev.mysql/doc/refman/8.0/zh-CN/string-functions.html

我还添加了WHERE条件，以便我们仅选择与给定子字符串条件匹配的行.

UPDATE wp_posts SET post_content = CONCAT( SUBSTRING_INDEX(post_content, '', post_content, LOCATE(' ) WHERE post_content LIKE '%%';

查询1:更新操作之前的数据

SELECT * FROM wp_posts; | post_content | | ------------------------------------------------------- | | adasdaadsa121324124 | | 1412123123adasdaafas |

查询2:更新操作后的数据

SELECT * FROM wp_posts; | post_content | | -------------------- | | adasdaadsa121324124 | | 1412123123adasdaafas |

在DB Fiddle上查看 I would like to run this type of query on my WP database to remove all span instances with id="more-":

UPDATE wp_posts SET post_content = REPLACE ( post_content, '', '');

But the number that follows the 'more-' in my example is a variable. How to write this query with someting like a wildcard: span id="more-*.

Thank you

解决方案

In MySQL version 8.0 and above, you can use REGEX_REPLACE() function. In absence of the same, some complicated string operations can be done. This is based on your confirmation, that the said sub-string is occurring only once in a value.

REPLACE() does not have any support for wildcards, patterns, regular expressions etc. It only replaces a given fixed substring with another fixed substring, in a bigger string.

Instead, we can try to extract portions of the post_content. We will extract the leading substring before the '' portion.

Now, we can simply Concat() these portions to get the required post_content. You can find details of various String functions used here: dev.mysql/doc/refman/8.0/en/string-functions.html

I have also added a WHERE condition, so that we pick only those rows which match our given substring criteria.

UPDATE wp_posts SET post_content = CONCAT( SUBSTRING_INDEX(post_content, '', post_content, LOCATE(' ) WHERE post_content LIKE '%%';

Query #1: Data before Update operations

SELECT * FROM wp_posts; | post_content | | ------------------------------------------------------- | | adasdaadsa121324124 | | 1412123123adasdaafas |

Query #2: Data after Update operations

SELECT * FROM wp_posts; | post_content | | -------------------- | | adasdaadsa121324124 | | 1412123123adasdaafas |

View on DB Fiddle

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SQL查询替换基于通配符的字符串