sql - Complex MySQL Delete Query -


current structure

sql erm diagram

as can see path can referenced multiple tables , multiple records within tables.

points can referenced 2 different tables.

my question

  1. i delete pathtype gets complicated path may owned more 1 pathtype deleting path without checking how many references there out of question.
  2. secondly, if path's reference pathtype i'm trying delete want delete path , records in pathpoints.
  3. lastly, if there no other references on point other records need deleted only if not used other object.

attempts far

delete pathtype1.*, path.*, pathpoints.*, point.* pathtype1,path,pathpoints,point pathtype1.id = 1 , pathtype1.path = path.id , (select count(*) pathtype1 pathtype1.path = path.id) < 1 , (select count(*) pathtype2 pathtype2.path = path.id) = 0

obviously above statement goes on isn't right way don't think because if 1 fails nothing deleted...

i think maybe isn't possible i'm attempting through 1 statement , may have iterate through each section , handle them based on outcome. not efficient don't see alternative @ time.

i hope clear. if have more questions or need clarification please not hesitate ask

first there no way in query if database allowed not. unmaintanable mess.

the preferred method create transaction, delete 1 table @ time starting bottommost child table. commit transaction. , of course have error handling entire transaction riolled if 1 delete fails maintain data integrity. if intended repeatedly, in stored proc.


Comments

Post a Comment

Popular posts from this blog

html - How to style widget with post count different than without post count -

i have border below li elements in wordpress widget types appropriate. element inside set block gives them nice easy click full width. the problem, when choose option "show post count" when adding widget such categories or archives displays post count plain text after tag , because tag block pushes post number text line below. whether choose show post count or not show post count still gives exact same element identifyer example "widget_categories". how style post count not on next line still keep links non post count list items full width? here's example on sidebar www.bbmthemes.com/themes/modular/blog-standard/ in order solve problem need remove display:block; for ul.widgets ul a , add in it's place line-height: 33px; what going achieve have same visual effect. what going lose doing links going work on text , not on "box". the other way out of find post count coming , make changes this. example change text count i
Read more

How to remove text and logo OR add Overflow on Android ActionBar using AppCompat on API 8? -

have researched death , cannot find answer. i have actionbar using appcompat. supporting api v7 (api v8 do). actionbar works api v11. api < v11 has problem of removing icon (and feature) actionbar without supplying overflow. big picture have app logo, app title, , 3 icons squidging same actionbar on low end phone. trying make room! i happy 1 of 2 solutions. either: a method of getting overflow functionality can retrieved pull down. (preferred) method of removing icon , text actionbar below current xml api 11+: <resources> <!-- base application theme api 11+. theme replaces appbasetheme res/values/styles.xml on api 11+ devices. --> <style name="appbasetheme" parent="theme.appcompat.light.darkactionbar"> <item name="android:actionbarstyle">@style/liteactionbarstyle</item> <item name="actionbarstyle">@style/liteactionbarstyle</item> </st
Read more

javascript - storing input from prompt in array and displaying the array -

i want take the inputs user prompt, store input in array, , display it. want take 10 inputs user using for loop. have tried do-while shown below. var givennames = new array(); var pattern = /[\w\d]{1,}/ig; do{ var name = prompt("enter names. letters , digits accepted!\nentering empty field stops asking",""); if(name && name.match(pattern)){givennames.push(name);} } while(name != ""); function displaynames(){ if(givennames.length > 0){ document.getelementbyid("list").innerhtml = "<span style='color:navy;font- weight:bold;'>given names are:<\/span><br><br>" + givennames.join("<br><br>"); } else { document.getelementbyid("list").innerhtml = "<span style='color:navy;font-weight:bold;'>nothing has been given!<\/span>"; } } how replace for loop? var givennames = new array();
Read more