How to write grouped fields into one line by mysql group_concat

This article is about how mysql group_concat can write grouped fields on a single line. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

Function: concatenate the values in the same group generated by group by and return a string result.

Function syntax:

Group_concat ([DISTINCT] the field to be connected [Order BY sort field ASC/DESC] [Separator 'delimiter'])

Example

Query the list of articles, using multiple tags for the same article as a field

Label table structure

CREATE TABLE `book_ tag` (`id` int (10) NOT NULL AUTO_INCREMENT, `tag_ name` varchar 'NOT NULL DEFAULT' 0' COMMENT 'tag name', `tag_ nums` int (10) NOT NULL DEFAULT'0' COMMENT 'reference', PRIMARY KEY (`id`) ENGINE=InnoDB DEFAULT CHARSET=utf8

Tagged article relation table

CREATE TABLE `tag_ book` (`id` int (10) NOT NULL AUTO_INCREMENT, `book_ id` int (10) NOT NULL DEFAULT'0' COMMENT 'book id', `tag_ id` int (10) NOT NULL DEFAULT' 0' COMMENT 'label ID', PRIMARY KEY (`id`) ENGINE=InnoDB DEFAULT CHARSET=utf8

Query

SELECT `b`.`book _ name`, `b`.`book _ flash`, `b`.`introduction`, GROUP_CONCAT (a.tag_name) FROM `book_ book``b`LEFT JOIN `book_tag_ book``t`t`.`book _ id` = `b`.`id`LEFT JOIN `book_ `taga`ON `a`.`id` = `t`.tag _ id`GROUP BY b.id

Result

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