The Knowlege base arranges tips and userful informations scattered on the web.
For more information, take a look to the introduction
Ring – Cache interface as a programming language integrationRing provides function-oriented cache interface for various backends. Repository: https://github.com/youknowone/ring/ Source: Ring – Cache interface as a programming language integration — Ring 0.7.2 documentation
https://asciinema.org/
isync: free IMAP and MailDir mailbox synchronizerisync is a command line application which synchronizes mailboxes; currently Maildir and IMAP4 mailboxes are supported. New messages, message deletions and flag changes can be propagated both ways. isync is suitable for use in IMAP-disconnected mode.Synchronization is based on unique message identifiers (UIDs), so no identification conflicts can occur …
isync: free IMAP and MailDir mailbox synchronizer Read More »
On these days I decided to tune a bit my new shiny linux server box. I started to set up fail2ban. I think fail2ban is very imporant nowadays because it is a good example of a tool for slowing down attacks without closing your server too much. Fail2ban is a daemon: it wll monitor your …
To understand Angular 4, after the “Hero” tutorial you should start from the Template syntax. We highlighted some statement in red below: Data direction Syntax Type One-way from data source to view target {{expression}} [target]=”expression” bind-target=”expression” Interpolation Property Attribute Class Style One-way from view target to data source (target)=”statement” on-target=”statement” Event Two-way [(target)]=”expression” bindon-target=”expression” Two-way …
Ci sono una nuova generazione di “nullasapienti”, persone che con una inutile laurea (tipicamente in legge) diventano giornalisti dilettanti, seguono i trend della “blogosfera” e leggono magari qualche bel libro di comunicazione. Il risultato è che pubblicano video che non sono scontati, non sono banali ma non sono neppure perle di saggezza. Sono ovvi. La …
Arduino is a great hardware for a lot of reason: easy to use, difficulto to break, it is a very solid 5-Volt board. But it a way too much and it has a very limited amount of RAM. So I started exploring other more “different” solutions. I need an economy chip with some RAM …
Sometimes you need to remove nasty duplicate on a table, based on a subset of the column. Oracle trick:
|
1 2 3 4 5 |
DELETE FROM your_table WHERE rowid not in (SELECT MIN(rowid) FROM your_table GROUP BY column1, column2, column3); |
Postgresql equivalent is ctid, so you can try something like
|
1 2 3 4 5 6 7 8 |
delete from mytable where exists (select 1 from mytable t2 where t2.name = mytable.name and t2.address = mytable.address and t2.zip = mytable.zip and t2.ctid > mytable.ctid ); |
SQLite demo:
|
1 2 3 4 5 6 7 8 9 10 11 12 13 |
create table dup_table (column1 text, column2 text, column3 text); insert into dup_table values('1','2','3'); insert into dup_table values('1','2','3'); insert into dup_table values('1','3','3'); DELETE FROM dup_table WHERE rowid not in (SELECT MIN(rowid) FROM dup_table GROUP BY column1, column2); select count(*) from dup_table; |
Also take a look at this old post on postgresql mailing list, if you incur in an older PostgreSQL version …
Removing duplicate rows in PostgreSQL, Oracle and SQLite Read More »
In Excel you can easily fill in a column with a list of values. Some times also in Emacs you my need to write down a bunch of similar code. The dotimes function with the “elsp eval” M-x : (Esc + : on windooze) will solve your trouble easily. Try out this code on scratch …
On some environment, on some customers, Oracle connections are drop after some idle time (i.e. 2 minutes). I have found a small plugin for Sql Developer to solve this issue: it is very handy and logs its usage. Code is also very clean keepalive extension for Oracle SQL Developer 4+https://github.com/scristalli/SQL-Developer-4-keepalive9 forks.86 stars.7 open issues.Recent commits: Fix …
