mysql foreach和递归查询嵌套怎么写？

我给你举个递归查询嵌套的例子，你看一下就明白了。

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select yr_student_info.name from yr_student_info where yr_student_info.school_id in (select yr_school_info.id from yr_school_info where yr_school_info.province='上海' and yr_school_info.city='上海')

Mysql中怎么进行递归查询?

概念说不一定理解，给你一个例子你自己参悟。

SELECT TEACHER

FROM C AS X

WHERE UNIQUE(SELECT TEACHER

FROM C AS Y

WHERE Y.TEACHER=X.TEACHER);

mysql 实现递归查询，节点有多个

[sql] view plain copy

CREATE FUNCTION `getChildList`(rootId INT)

RETURNS varchar(1000)

BEGIN

DECLARE sChildList VARCHAR(1000);

DECLARE sChildTemp VARCHAR(1000);

SET sChildTemp =cast(rootId as CHAR);

WHILE sChildTemp is not null DO

IF (sChildList is not null) THEN

SET sChildList = concat(sChildList,',',sChildTemp);

ELSE

SET sChildList = concat(sChildTemp);

END IF;

SELECT group_concat(id) INTO sChildTemp FROM user_role where FIND_IN_SET(parentid,sChildTemp)0;

END WHILE;

RETURN sChildList;

END;

[sql] view plain copy

/*获取子节点*/

[sql] view plain copy

php与mysql表中如何求递归求和汇总?

function sumShuzi($tree, $updateData = array()) {

$sum = 0;

// foreach($tree as $key = $item) {  //这句话有毒

foreach($tree as $key = $item) {

if(isset($item['children'])) {

$oldPshuzi = $tree[$key]['Pshuzi'];

$tree[$key]['Pshuzi'] = sumShuzi($item['children'], $updateData);

if($oldPshuzi != $tree[$key]['Pshuzi']) {

$updateData[$item['id']] = array($tree[$key]['Pshuzi'], $tree[$key]['Pname_ch']);

}

}

$sum += $tree[$key]['Pshuzi'];

}

return $sum;

}

$tree = json_decode('[{"id":"1","Pid":"0","Pname_ch":"\u6e20\u9053\u90e8","Pshuzi":"1638000","children":[{"id":"4","Pid":"1","Pname_ch":"\u9500\u552e\u4e8c\u90e8","Pshuzi":"895000","children":[{"id":"13","Pid":"4","Pname_ch":"\u5468\u7ecf\u7406","Pshuzi":"28","children":[{"id":"28","Pid":"13","Pname_ch":"\u6e56\u5357","Pshuzi":"158000"},{"id":"35","Pid":"13","Pname_ch":"\u65b0\u7586","Pshuzi":"19000"}]},{"id":"40","Pid":"4","Pname_ch":"\u9648\u7ecf\u7406","Pshuzi":"5000"}]}]}]', true);

//$tree是具有父子关系的数据树

sumShuzi($tree, $updateData);

foreach ($updateData as $id = $item) {

$sql = "update your_table set Pshuzi={$item[0]} where id={$id}";

mysqli_query($db, $sql);    //$db是你的数据库连接结果

}

mysql递归查询

你这个表设计有问题， 重设计个表pid 为院系 下级为班级

暂时想这么多，自己考虑吧

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