Showing entries 1 to 6
Displaying posts with tag: function (reset)
LEVENSHTEIN MySQL stored function

At Open Query we steer clear of code development for clients. We sometimes advise on code, but as a company we don’t want to be in the programmer role. Naturally we do write scripts and other necessities to do our job.

Assisting with an Open Source project, I encountered three old UDFs. User Defined Functions are native functions that are compiled and then loaded by the server similar to a plugin. As with plugins, compiling can be a pest as it requires some of the server MySQL header files and matching build switches to the server it’s going to be loaded in. Consequentially, binaries cannot be considered safely portable and that means that you don’t really want to have a project rely on UDFs as it can hinder adoption quite severely.

Since MySQL 5.0 we can also use SQL stored functions and procedures. Slower, of course, but …

[Read more]
Truly Random and Complex Password Generator - Part 2 of 2

Permalink: http://bit.ly/1tMM9h2



In the first part of this entry, it was shown how its possible that a password from a normal user would significantly be weaker than that from a complex and randomly generated one.

Note: in the strictest sense, there is no such thing as an uncrackable password. Passwords can be uncrackable only in theory, i.e. the mathematical probability of a password being guessed correctly-- no matter how infinitesimally small the odds are, the possibility of a right guess is always present. Also, passwords are uncrackable only technically-- given enormous resources and time any password can be cracked.

Here is a function for a truly random and complex password generator which is based on …

[Read more]
MySQL - My new playground

Note: It was my first attempt using the MySQL UDF Api back then. The library is still maintained and got some new features. Check out the new MySQL Infusion UDF.

Read the rest »

MySQL Function to Convert Date To Words

Recently I saw a MySQL Stored Function requirement on Experts-Exchange for converting date into some specific words format. You may find MySQL function for date to words conversion online; even udfs might be ready, but I decided to write my own. I wrote this simple function mainly based on SELECT CASE to convert dates in […]

Case Insensitive REPLACE() for MySQL

One request I occasionally see is for a case insensitive version of REPLACE() for MySQL. I wrote this a while back, but here it is now for all of you to play around with. It uses a basic naïve string search algorithm, so can be slow under some circumstances.

DELIMITER $$
 
DROP FUNCTION IF EXISTS `replace_ci`$$
CREATE FUNCTION `replace_ci` ( str TEXT,needle CHAR(255),str_rep CHAR(255))
    RETURNS TEXT
    DETERMINISTIC
    BEGIN
        DECLARE return_str TEXT DEFAULT '';
        DECLARE lower_str TEXT;
        DECLARE lower_needle TEXT;
        DECLARE pos INT DEFAULT 1;
        DECLARE old_pos INT DEFAULT 1;
 
        SELECT lower(str) INTO lower_str;
        SELECT lower(needle) INTO lower_needle;
        SELECT locate(lower_needle, lower_str, pos) INTO pos;
        WHILE pos > 0 DO
            SELECT concat(return_str, substr(str, old_pos, pos-old_pos), str_rep) INTO return_str;
            SELECT pos + char_length(needle) INTO pos;
            SELECT …
[Read more]
Liveblogging: Extending MySQL by Brian ?Krow? Aker

Liveblogging: Extending MySQL by Brian “Krow” Aker

Brian wins the award for “most frequent great quotes during a talk”.

Before MySQL 5.1 a UDF was the only way to extend MySQL.

All you need in a UDF is: init() execute() deinit()

my_bool id3_parse_init(UDF_INIT *initid UDF_ARGS *args, char *message)

UDF_ARGS tell you about incoming args
char *message is the output that might return
args->arg_count is the # of args

WARNING: use STRICT mode in MySQL, otherwise there are tons of silent failures.

“When you work on databases you start to put everything in databases. Tip, don’t put a DVD into a database, because really long BLOBs aren’t actually supported….”

In MySQL 5.1, you can now install plugins (example is memcache_servers plugin):

mysql> INSTALL PLUGIN memcache_servers SONAME …

[Read more]
Showing entries 1 to 6