Posts Tagged with "sql"

How to update fields from another table in MySQL

Posted by Stanislav Furman on May 28, 2014

This article is to continue the series of short handy MySQL tips that I started a while ago. 

If you need to update a number of column fields in a MySQL table with data from another table, there is a simple way to do it. Lets say you need to update user phone numbers in table1 with the corresponding phone numbers from table2. Then you could run the following query.

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Meet AMPPS - a good alternative for XAMPP and WAMP

Posted by Stanislav Furman on October 7, 2013
Meet AMPPS - a good free alternative for XAMPP and WAMP

Concatenating NULL and blank fields in MySQL

Posted by Stanislav Furman on May 17, 2013
How to concatenate empty and null fields in MySQL database

How to protect against SQL injection, and why SQL injection is dangerous

Posted by Stanislav Furman on May 14, 2013

I am quite sure that most of web developers know what the SQL injection is, and nowdays it seems that even junior developers know basics on how to protect web applications against this type of hacker attack. However, I often see web developers underestimate the level of potential threat. Some web developers think: "We are too small to be interesting for hackers", but they forget that security wholes in their applications can be used to attack other resources, systems and users.

In this post I am not going to show how to attack web applications using an SQL injection, but I'd like to show why SQL injection is dangerous and also how to protect against SQL injection.

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MySQL. How to insert a row or update if exists in MySQL.

Posted by Stanislav Furman on February 25, 2013
Insert a row into DB, or update row on duplicated key in MySQL.

Visual Representation of SQL Joins on a graphical diagram

Posted by Stanislav Furman on February 18, 2012

For some programmers (especially for begginers) it might be a bit difficult to understand how do SQL joins work in real life. In fact, sometimes even experienced software developers are not able to explain what is the difference between JOINLEFT JOIN and RIGHT JOIN.

Luckily, I found, perhaps, one of the best visual representations of SQL joins I have ever seen which will definately help to understand the mechanism of SQL joins.

Visual Representation of SQL Joins, graphic diagram

 

See more graphical diagrams and explanations here