SQL Server : count pairs from two different columns -


i have query need application i'm building, i'm struggling find best answer.

suppose have table named messages, following columns:

messageid, from, to, text

i want count messages between from , to such if table looks this:

id    text ------------------  1      b     hi  2    b    hello  3      c   test

so want result 

a, b, 2 a, c, 1

appreciate help

similar answer gordon, posted 20 seconds later, 1 important difference. ansi sql requires no derived columns appear in group by clause. first use cte compute least , greatest of to/from pairs, , aggregation query on cte. in case, end grouping on actual, not derived, columns.

with cte (     select         case when [from] <  [to] [from] else [to] end [from],         case when [from] >= [to] [from] else [to] end [to]     yourtable )  select     [from], [to], count(*) cnt cte group     [from], [to]

note should avoid using sql keywords such from name columns , tables. query work, absolutely have use column [from], because without brackets sql server confound from keyword.


Comments

Post a Comment

Popular posts from this blog

PHP and MySQL WP -

i trying accomplish 2 things here code. writing php directly wp page using insert php plugin. 1) query mysql database , return results 1 column 4 columns. 2) make each result own hyperlink directs user new wp page runs new query on page. i able query show results , turn results dynamic hyperlink, cannot formatting down. right returns result 1 column. here have: [insert_php] $servername = "localhost"; $username = "login"; //edited privacy $password = "password"; //edited privacy $database = "database"; //edited privacy // create connection $conn = new mysqli($servername, $username, $password, $database); // check connection if ($conn->connect_error) { die("connection failed: " . $conn->connect_error); } echo "connected successfully"; //get results database $result = mysqli_query($conn,"select mine mines order mine"); $all_property = array(); //declare array saving property //showing proper...
Read more

android - InAppBilling registering BroadcastReceiver in AndroidManifest -

i'm implementing inapp billing in android app. works well, however, i'm trying decouple broadcast receiver activity manifest. suggestion in android's trivialdrive sample: // important: dynamically register broadcast messages updated purchases. // register receiver here instead of <receiver> in manifest // because call getpurchases() @ startup, therefore can ignore // broadcasts sent while app isn't running. // note: registering listener in activity bad idea, done here // because sample. regardless, receiver must registered after // iabhelper setup, before first call getpurchases(). currently there's class extends broadcastreceiver : public class iabbroadcastreceiver extends broadcastreceiver { /** * intent action receiver should filter for. */ public static final string action = "com.android.vending.billing.purchases_updated"; private final iabbroadcastlistener mlistener; public iabbroadcastreceiver(iabbroadcastlistener listener) { m...
Read more

go - golang pprof for c library code -

i have been trying profile golang application pprof, seems details of c code(linked static library) missed in output result. flame graph from frame graph can see c code time consuming reported within "runtime._externalcode", no details @ all. , sure static library compiled debug enable. so there way make pprof details(like stack trace) of 3rd party c code? or there other golang profiling tool this?
Read more