Roei's Tips Stream - Roei's stream of ideas, tips & creativity

Interview Question: Select only Prime numbers from table

Jul 28, 2018Roei TabakInterview Questions, MSSQL, MySQL

As part of my daytime job, I conduct professional interviews for candidates. For that, I’m always on the search for good interview questions. I regard a good question if it’s not too complicated, has a number of ways to solve, and if needed, can be solved programmatically with SQL or C / C# / JAVA languages.

Now that I’m done with asking the prime number question (I need to change questions every now and then), I thought I will post the solution here.

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Calculate average time from DateTime MySql

Jul 7, 2018Roei TabakMySQL

Calculating average time from DateTime field in MySql might come in handy in cases like getting the average arrival time, departure time, service sampling etc. In my case, I have a database with records on my arrival to work, and I wanted to calculate time average time that I arrive by the office, and then calculate how much time I spend in traffic, depending on when I leave my home.

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Prevent cookie hijacking (session hacking)

Jun 10, 2018Roei TabakPHP

First of all, what is “Cookie Hijacking”?

By Wikipedia, it’s an “exploitation of a valid computer session to gain unauthorized access to information or services in a computer system. In particular, it is used to refer to the theft of a magic cookie used to authenticate a user to a remote server”.

Which basically means, gaining access to an information system or a website without logging in, as the user that the cookie (or session) belongs to him.

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Delete files older than x days automatically

Apr 21, 2018Roei TabakProject, Windows

Sometimes it is necessary to delete files that are older than 1 day, a week, or even a year. We just don’t need them anymore, maybe they are irrelevant, take up a lot of space on our hard drive or just a by-product of another process.

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Quick Tip: WordPress template drop-down list is missing

Apr 7, 2018Roei TabakPHP, Quick Tip, WordPress

If you can find the list of page templates in the page editor on WordPress try this quick fix that will probably help.

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Quick Tip: prevent caching of resources using .htaccess

Mar 1, 2018Roei TabakPHP, Quick Tip

A quick and easy way to prevent specific resources to be cached by sending the correct headers in .htaccess file.

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Quick Tip: Create a copy of a database table MSSQL programmatically

Feb 10, 2018Roei TabakMSSQL

Have you ever wanted to create a copy of a database table, programmatically?

Could be a part of a stored procedure as a temporary table, or just a quick way of duplicating structure and constraints of the original one.

If so, this Transact-SQL script maybe what you’re looking for.

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Send Email on ESP8266 with Arduino

Feb 2, 2018Roei Tabak1 CommentArduino, ESP8266, PHP

Sending an email is probably the most convenient way of communicating data or informing us of an event from our ESP8266. It’s cross-platform, works on every device and very reliable. It can alert us when one of the sensors detected something (PIR sensor for movement, MQ2 for air quality or any other environmental sensor).
There are a few ways to get that done, and in this post, I’ll show you my preferable way.

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Connecting ESP8266 microcontroller to a WiFi network

Jan 21, 2018Roei Tabak4 CommentsArduino, ESP8266, Home Automation

This seems like a topic that has a lot of cover on the internet, and many sites have code snippets for connecting ESP8266 to WiFi networks, however, after using a lot of ESP8266 in my projects I want to recommend my own take on how to achieve this.

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Quick Tip: {REMOTE_ADDR} behind proxy or Firewall .htaccess

Jan 7, 2018Roei TabakPHP, Quick Tip

Handling resources, redirects and other operations is very easy and useful using the .htaccess file of Apache web server.
Sometimes, we want to block or redirect traffic based on its network IP address.

But what to do when %{REMOTE_ADDR} returns the wrong address? (more…)