sql server - Remove Duplicates ... With NULLs -


in ms sql server trying remove duplicates table nulls. que groans. lots , lots of nulls. bottom line need retain 1 copy of duplicate record or without nulls. wantnull act normal record value of "null" duration of operation, , go being real null. possible? there simpler solution?

table1 looks like:

uid        data1    data2    1                  null         2                  null        3           b        abc      4           b        abc        5           c        null       6           d        ghj

i want command throw away line 2 , 4 , keep rest. (the select testing.)

;select uid, data1, data2  table1 t  not exists (     select 1     table1 t2            t2.data1 = t.data1       , t2.data2 = t.data2       , t2.uid >= t.uid       )     , data1 not null

note: select distinct not work duplicates have different timestamps.

this should do:

;with cte (     select  *,             rn = row_number() over(partition data1,data2 order uid)     table1 ) delete --select * cte rn > 1

updated following comment

ok, if having issues delete amount of rows, could try creating table id's want delete , batch delete (you have test batch row amount, though). idea (assuming uid pk):

;with cte (     select  *,             rn = row_number() over(partition data1,data2 order uid)     table1 ) select [uid] rowstodelete cte rn > 1;  create index i_uid on rowstodelete([uid]);  while 1=1 begin     delete top (10000)     table1 t     inner join rowstodelete l           on t.[uid] = l.[uid]     if @@rowcount < 10000 break; end

Comments

Post a Comment

Popular posts from this blog

jquery - How can I dynamically add a browser tab? -

since using iframes house external pages are, accounts "not preferred method" , disallowed sites (flickr, one), want dynamically generate browser tabs. e.g., when user submits form, want dynamically generate tab on browser in response submitted. e.g., might want add new tab url like: http://www.bigsurgarrapata.com/contact how in jquery? you want form target attribute action attribute. http://www.w3schools.com/tags/att_form_target.asp browsers have ultimate control on result of target attribute open new tab value of _blank. <form action="contact_submit.php" target="_blank" method="post">
Read more

keyboard - C++ GetAsyncKeyState alternative -

i using windows.h library's getasynckeystate function define key pushed on keyboard . here program returns int value of pushed key example. #include <iostream> #include <windows.h> using namespace std; int main (){ char i; for(i=8;i<190;i++){ if(getasynckeystate(i)== -32767){ cout<<int (i)<<endl; } } return 0; } but trying make opengl simple game , function appeared slow . there function not need cycle 180 times , if statement . thanks you're trying make opengl game, you're going use glfw. if that's case can away using glfwgetkey() such: if (glfwgetkey(glfw_key_up) == glfw_press) {...} if (glfwgetkey(glfw_key_down) == glfw_press) {...} that method nicely explained in tutorial 6 opengl-tutorial.org . should start first tutorial of beginners tutorials , later intermediate tutorials . if you're going make win32 window can listen wm_keydown or wm_keyup messages , virtua...
Read more

android - java.net.UnknownHostException(Unable to resolve host “URL”: No address associated with hostname) -

i developing app testing asp.net webservice in android.for simple webservice adding 2 numbers used.where numbers passed parameters.the result in dialogue.the webserver works in local. when application runs following result exception.i provided internet permission in manifest. java.net.unknownhostexception(unable resolve host “ http://url.com/ ”: no address associated hostname) my code given below main activity public static string rslt=""; /** called when activity first created. */ @override public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_main); button b1=(button)findviewbyid(r.id.button1); final alertdialog ad=new alertdialog.builder(this).create(); b1.setonclicklistener(new onclicklistener() { @override public void onclick(view arg0) { // todo auto-generated method stub try { ...
Read more