De-duplicating many-to-many relationships in MySQL lookup table -

-

i've inherited database includes lookup table find other patents related given patent.

so looks 

╔════╦═══════════╦════════════╗ ║ id ║ patent_id ║ related_id ║ ╠════╬═══════════╬════════════╣ ║ 1  ║     1     ║     2      ║ ║ 2  ║     1     ║     3      ║ ║ 3  ║     2     ║     1      ║ ║ 4  ║     2     ║     3      ║ ║ 5  ║     3     ║     2      ║ ╚════╩═══════════╩════════════╝

and want filter out reciprocal relationships. 1->2 , 2->1 same purposes want 1->2.

i don't need make edit in table, need query returns list of unique relationships, , while i'm sure it's simple i've been banging head against keyboard far long.

here clever query can try using. general strategy identify unwanted duplicate records , subtract them away entire set.

select t.id, t.patent_id, t.related_id t left join (     select t1.patent_id t1_patent_id, t1.related_id t1_related_id     t t1 left join t t2     on t1.related_id = t2.patent_id     t1.patent_id = t2.related_id , t1.patent_id > t1.related_id ) t3 on t.patent_id = t3.t1_patent_id , t.related_id = t3.t1_related_id t3.t1_patent_id null

here inner temporary table generated query. can convince applying logic in where clause select correct records. non-duplicate records characterized t1.patent_id != t2.related_id, , these records retained. in case of duplicates (t1.patent_id = t2.related_id), record chosen each pair of duplicates 1 patent_id < related_id, requested in question.

╔════╦══════════════╦═══════════════╦══════════════╦═══════════════╗   ║ id ║ t1.patent_id ║ t1.related_id ║ t2.patent_id ║ t2.related_id ║ ╠════╬══════════════╬═══════════════╬══════════════╬═══════════════╣ ║ 1  ║      1       ║       2       ║      2       ║       1       ║ * duplicate ║ 1  ║      1       ║       2       ║      2       ║       3       ║ ║ 2  ║      1       ║       3       ║      3       ║       2       ║ ║ 3  ║      2       ║       1       ║      1       ║       2       ║ * duplicate ║ 3  ║      2       ║       1       ║      1       ║       3       ║ ║ 4  ║      2       ║       3       ║      3       ║       2       ║ * duplicate ║ 5  ║      3       ║       2       ║      2       ║       1       ║ ║ 5  ║      3       ║       2       ║      2       ║       3       ║ * duplicate ╚════╩══════════════╩═══════════════╩══════════════╩═══════════════╝

click link below running example of query.

sqlfiddle


Comments

Post a Comment

Popular posts from this blog

javascript - Chart.js (Radar Chart) different scaleLineColor for each scaleLine -

-
Image
i try , create radar chart using chart.js has various colours each scaleline, or coloured between scalelines. wondering if possible? from: to: i have working graph, though there doesn't seem method change individual scale lines. kind regards leigh you can extend radar chart type this, so chart.types.radar.extend({ name: "radaralt", initialize: function (data) { chart.types.radar.prototype.initialize.apply(this, arguments); var originalscaledraw = this.scale.draw; var ctx = this.chart.ctx; this.scale.draw = function () { var linewidth = this.linewidth; // bypasses line drawing in originalscaledraw this.linewidth = linewidth; originalscaledraw.apply(this, arguments); ctx.linewidth = this.linewidth; var scale = this; // draw chart.helpers.each(scale.ylabels, function (label, index) { // color of ...
Read more

apache - Error with PHP mail(): Multiple or malformed newlines found in additional_header -

-
suddenly have started receiving above error without changes having been made script. host 1and1 (i know...) the script still works fine on different server, , suspicion there must have been server config change has lead this, although hosts plead ignorance. there's no information on above error @ in google can find - have ideas? server running apache if helps. had similar problem. came out of blue. no php code changed. what changed: php upgraded 5.5.25-1 5.5.26. a security risk in php mail() function has been fixed , newlines in additional_headers allowed no more. because newlines mean: starts email message (and surely don't want inject newlines through headers followed evil message). what have worked fine, e.g. having newlines after headers or passing whole message additional_headers , function no more. solution : sanitize headers. no multiple newlines in additional_headers argument. these count "multiple or malformed newlines":...
Read more

java - Android – MapFragment overlay button shadow, just like MyLocation button -

-
Image
i'm struggling add shadow custom overlay button on google map. goal make custom button google's mylocation button. here's how app looks now: layout.xml <relativelayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" xmlns:map="http://schemas.android.com/apk/res-auto" android:layout_height="match_parent" android:layout_width="match_parent" style="@style/apptheme"> <fragment android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/map" tools:context=".mapsactivity" android:name="com.google.android.gms.maps.supportmapfragment" android:layout_alignparentend="true" android:layout_alignparentstart="true" android:layout_alignparentbottom="true" ...
Read more