Postgres查询以获取所有子代ID

本文介绍了Postgres查询以获取所有子代ID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

我是SQL新手，到目前为止只写了非常基本的查询。

我有一个看起来像这样的表

item_full_name varchar（65535） item_id bigint item_owners varchar（255） item_approver_group varchar（255） item_state varchar （255） item_parent_id bigint item_children varchar（65535）

最初item_children是所有行均为空，但每个项目都有一个item_parent_id，并且不为null。我想编写一个查询，查看所有行&

例如。

item_full_name | item_id | item_owners | item_parent_id | item_children item1 | 1 | o1，o2 | 2 | item2 | 3 | owner8 | 2 | item3 | 2 | owner6 | 0 | item4 | 4 | owner7 | 1 |

应将其转换为

item_full_name | item_id | item_owners | item_parent_id | item_children item1 | 1 | o1，o2 | 2 | 4 item2 | 3 | owner8 | 2 | item3 | 2 | owner6 | 0 | 3,1 item4 | 4 | owner7 | 1 |

任何指针都会有所帮助。谢谢！

解决方案

我开始走递归CTE的道路，但后来意识到您只想要每个孩子的孩子父级，在单个级别上。一种方法是通过 item_parent_id 汇总 item_id 。然后，将原始表格加入此结果中，以获取每个父母的孩子的CSV列表。

与cte AS（选择item_parent_id，STRING_AGG（item_id :: text，'，'）AS item_children 从yourTable GROUP BY item_parent_id ） SELECT t1 .item_full_name， t1.item_id， t1.item_owners， t1.item_parent_id， t2.item_children from yourTable t1 左联接cte t2 on t1.item_id = t2.item_parent_id OR BY BY t1.item_full_name;

演示

I'm an SQL noob and wrote only very basic queries so far.

I have a table that looks like this

item_full_name varchar(65535) item_id bigint item_owners varchar(255) item_approver_group varchar(255) item_state varchar(255) item_parent_id bigint item_children varchar(65535)

Initially item_children is empty for all the rows but each item has a item_parent_id and is not null. I want to write a query that looks at all the rows & corresponding parent ids and updates each row's item_children with a string of children ids separated by comma.

for eg.

item_full_name | item_id | item_owners | item_parent_id | item_children item1 | 1 | o1, o2 | 2 | item2 | 3 | owner8 | 2 | item3 | 2 | owner6 | 0 | item4 | 4 | owner7 | 1 |

This should be transformed to

item_full_name | item_id | item_owners | item_parent_id | item_children item1 | 1 | o1, o2 | 2 | 4 item2 | 3 | owner8 | 2 | item3 | 2 | owner6 | 0 | 3,1 item4 | 4 | owner7 | 1 |

Any pointers would be helpful. Thanks!

解决方案

I started off going down the road of a recursive CTE, but then realized that you just want the children of each parent, at that single level. One approach is to aggregate the item_id by item_parent_id. Then, join your original table to this result to obtain the CSV list of children for each parent.

WITH cte AS ( SELECT item_parent_id, STRING_AGG(item_id::text, ',') AS item_children FROM yourTable GROUP BY item_parent_id ) SELECT t1.item_full_name, t1.item_id, t1.item_owners, t1.item_parent_id, t2.item_children FROM yourTable t1 LEFT JOIN cte t2 ON t1.item_id = t2.item_parent_id ORDER BY t1.item_full_name;

Demo