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Displaying posts with tag: PHP (reset)
Jul
16
2012
PHP for MySQL Striped View
Posted by Michael McLaughlin on Mon 16 Jul 2012 07:47 UTC
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Back in May I explained how to create MySQL striped views with session variables. A couple folks wanted to know how to implement them through PHP programs. The trick is sharing the same connection between a call to the function before a query against the striped view.

I’ve updated the MySQL example beyond the Hobbit analogy from the prior post. It now uses the following database components:

  • An APPLICATION_USER table
  • A striped AUTHORIZED_USER view
  • A FUNCTION_QUERY view to optimize function calls
  • A SET_LOGIN function
  • A GET_LOGIN_ID function
  • A GET_USER_ID function

The definition of the APPLICATION_USER table is: 

CREATE TABLE application_user
( user_id …
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Jul
16
2012
Free Oracle PHP Book
Posted by Michael McLaughlin on Mon 16 Jul 2012 04:54 UTC
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Six years ago, I wrote Oracle Database 10g Express Edition PHP Web Programming for the release of the express edition. It was a lot of fun to write because I enjoy the PHP programming language, but unfortunately sales didn’t measure up too well. That’s probably because the population of PHP developers working with Oracle was small.

Today it seems there are more PHP developers working with Oracle 11g. While the population of PHP community for Oracle 11g is still smaller than for MySQL, it continues to grow year-over-year.

The FREE …

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Jul
16
2012
One-way Password Crypting Flaws
Posted by Open Query on Mon 16 Jul 2012 04:08 UTC
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I was talking with a client and the topic of password crypting came up. From my background as a C coder, I have a few criteria to regard a mechanism to be safe. In this case we’ll just discuss things from the perspective of secure storage, and validation in an application.

  1. use a digital fingerprint algorithm, not a hash or CRC. A hash is by nature lossy (generates evenly distributed duplicates) and a CRC is intended to identify bit errors in transmitted data, not compare potentially different data.
  2. Store/use all of the fingerprint, not just part (otherwise it’s lossy again).
  3. SHA1 and its siblings are not ideal for this purpose, but ok. MD5 and that family of “message digests” has been proven flawed long ago, they can be “freaked” to create a desired outcome. Thus, it is possible to …
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Jul
15
2012
PHP/MySQL Query
Posted by Michael McLaughlin on Sun 15 Jul 2012 05:59 UTC
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Somebody wanted an example of how to handle column values using PHP to query a MySQL database. While I thought there were enough examples out there, they couldn’t find one that was code complete.

Well, here’s one that works using a static query. If you want to use a prepared statement, check this earlier post. 

<html>
<header>
<title>Static Query Object Sample</title>
<style type="text/css">
  /* HTML element styles. */
  table {background:white;border-style:solid;border-width:3px;border-color:black;border-collapse:collapse;}
  th {text-align:center;font-style:bold;background:lightgray;border:solid 1px gray;}
  td {border:solid 1px gray;}
 
  /* Class tag element styles. */
  .ID {min-width:50px;text-align:right;}
  .Label {min-width:200px;text-align:left;}
</style>
</header>
<body>
<?php
  // …
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Jul
14
2012
Statistical functions in MySQL
Posted by Robert Eisele on Sat 14 Jul 2012 01:39 UTC
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Even in times of a growing market of specialized NoSQL databases, the relevance of traditional RDBMS doesn't decline. Especially when it comes to the calculation of aggregates based on complex data sets that can not be processed as a batch like Map&Reduce. MySQL is already bringing in a handful of aggregate functions that can be useful for a statistical analysis. The best known of this type are certainly:

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Jul
14
2012
Statistical functions in MySQL
Posted by Robert Eisele on Sat 14 Jul 2012 01:39 UTC
Tags:

Even in times of a growing market of specialized NoSQL databases, the relevance of traditional RDBMS doesn't decline. Especially when it comes to the calculation of aggregates based on complex data sets that can not be processed as a batch like Map&Reduce. MySQL is already bringing in a handful of aggregate functions that can be useful for a statistical analysis. The best known of this type are certainly:

Read More »

Jun
27
2012
Lock Wait Timeout Errors or Leave Your Data on the Server
Posted by Brian Moon on Wed 27 Jun 2012 06:12 UTC
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If you use MySQL with InnoDB (most everyone) then you will likely see this error at some point. There is some confusion sometimes about what this means. Let me try and explain it.

Let's say we have a connection called A to the database. Connection A tries to update a row. But, it receives a lock wait timeout error. That does not mean that connection A did anything wrong. It means that another connection, call it B, is also updating a row that connection A wants to update. But, connection B has an open transaction that has not been committed yet. So, MySQL won't let you update that row from connection A. Make sense?

The first mistake people may make is looking at the code that throws the error to find a solution. It is hardly ever the code that throws the error that is the problem. In our case, it was code that was doing a simple insert into a table. I had a look at our processing logs around the time that the errors were …

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Jun
26
2012
Stop comparing stuff you don't understand
Posted by Brian Moon on Tue 26 Jun 2012 04:09 UTC
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I normally don't do this. When I see someone write a blog post I don't agree with, I often just dismiss it and go on. But, this particular one caught my attention. It was titled PHP vs Node.js: Yet Another Versus. The summary was:

Node.js = PHP + Apache + Memcached + Gearman - overhead

What the f**k? Are you kidding me? Clearly this person has NEVER used memcached or Gearman in a production environment that had any actual load.

Back in the day, when URLs and filesystems had a 1:1 mapping, it made perfect sense to have a web server separate from the language it is running. But, nowadays, any PHP app with attractive URLs running behind the Apache web server is going to need a .htaccess file, which tells the server a regular expression to check before serving up a file. Sound complex and awkward …

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Jun
12
2012
PHP libmysqlclient.so.16 error and MySQL Percona Server 5.5
Posted by Vladimir on Tue 12 Jun 2012 14:11 UTC
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If you ever get an error with MySQL client library:

php: error while loading shared libraries: libmysqlclient.so.16: cannot open shared object file: No such file or directory

while using Percona MySQL Server 5.5 just go ahead and install Percona-Server-shared-compat package from Percona Repo:

yum install Percona-Server-shared-compat

Jun
02
2012
Interviewing tip..
Posted by Keith Murphy on Sat 02 Jun 2012 03:15 UTC
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I've been involved in a number of interviews over the last few weeks as a client has been loking for a MySQL DBA. When you are looking for position as a DBA in a large scale environement there are some very important things you have to know.

You absolutely must know a scripting language. In a smaller environment this often isn't necessary. You will live and die by this in a large environment. I asked every applicant one specific question..if you had to change a mysql server variable on a pool of 100 mysql servers how would you do this? It's easy when it's one,two or even a dozen servers. just log in, change the my.cnf and change it "on the fly" if you can. Restart mysql if you can't.

You going to do that to 100 servers? It will take all day and be prone to failures. Scripting is the key here. Even just bash shell scripting can be very powerful. In another post I will cover a simple bash script to loop through a …

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