How to SELECT and sort it by parent-children in MySQL -

i have table looks this

id  parent_id   name    address     email   telephone 2   null        name    address     email   phone 3   null        name2   address2    email2  phone2 4   null        name3   address3    email3  phone3 5   null        name4   address4    email4  phone4 6   null        name6               email6  phone6  7   5           name7               email7  phone7  8   null        name8               email8  phone8  

and want select on select rows, if row has parent displayed after parent. in case rows this

id  parent_id   name    address     email   telephone 2   null        name    address     email   phone 3   null        name2   address2    email2  phone2 4   null        name3   address3    email3  phone3 5   null        name4   address4    email4  phone4 7   5           name7               email7  phone7  6   null        name6               email6  phone6  8   null        name8               email8  phone8  

the row id=7 goes before 1 id=6 because parent_id of 1 id=7 5 placed directly after row.

you can using case statement in order by clause:

select *  yourtable order case when parentid null id else parentid end, parentid 

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