sql - extra column in MySQL, can I drop it? -


i have database i'm creating , made 1 1 connection table in mysql, below screen shot. question can drop column (assembly factory_id) created when made connection? want single (factory_id) mess connection made? should drop (factory_id) , let connection stay? i'm noob, thanks!

enter image description here

i assuming comment "but should drop table?" meant "but should drop column?".

short answer: if safe, should delete column - there's no reason keep cluttering database , minds of future developers.

long answer: how determine if it's safe: if 1) value in factory_id , identical assembly factory_id, eg, duplicate value of each other, , 2) no other tables or program code refer assembly factory_id, can safely delete assembly factory_id.

however, if there's chance ever mean different things (not sample of 20 or rows), can't delete it. see fiddle: http://sqlfiddle.com/#!9/0bf17/1

if same, parts of database or code refer assembly factory_id, can refactor database or code parts refer factory_id instead , delete assembly factory_id.

when doing this, should make tests verify state of queries , programs after change same state before change.


Comments

Post a Comment

Popular posts from this blog

javascript - AngularJS custom datepicker directive -

i make custom datepicker directive custom template. but have no idea how start building it... how include date data directive? i appreciate guide or give me advice work on more precisely. it might you! follow below steps html code sample: <label>birth date</label> <input type="text" ng-model="birthdate" date-options="dateoptions" custom-datepicker/> <hr/> <pre>birthdate = {{birthdate}}</pre> <script type="text/ng-template" id="custom-datepicker.html"> <div class="enhanced-datepicker"> <div class="proxied-field-wrap"> <input type="text" ui-date-format="yy-mm-dd" ng-model="ngmodel" ui-date="dateoptions"/> </div> <label> <button class="btn" type="button"><i class="icon-calendar"></i>
Read more

javascript - jQuery date picker - Disable dates after the selection from the first date picker -

<!doctype html> <html lang="en"> <head> <meta charset="utf-8"> <title>jquery ui datepicker - default functionality</title> <link rel="stylesheet" href="//code.jquery.com/ui/1.11.4/themes/smoothness/jquery-ui.css"> <script src="//code.jquery.com/jquery-1.10.2.js"></script> <script src="//code.jquery.com/ui/1.11.4/jquery-ui.js"></script> <link rel="stylesheet" href="/resources/demos/style.css"> <script> $(function () { $("#datepicker1").datepicker(); }); </script> <script> $(function () { $("#datepicker2").datepicker(); }); </script> </head> <body> <p>date 1: <input type="text" id="datepicker1"></p> <p>date 2: <input type="t
Read more