...some deliberation, we decided to implement a "schema-less" storage system on top of MySQL rather than use a completely new storage system. This post attempts to describe the high...
In MySQL comparing zero to a string 0 = "any string" is always true! So when you want to compare a string with a value of an integer column, you have...
...lives in another table, you need to JOIN both tables during the UPDATE. In MySQL you can do it like this: UPDATE employees LEFT JOIN departments ON employees.department_id = departments.id...
Directly from the MySql docs: There are three likely causes for this error message. Usually it indicates network connectivity trouble and you should check the condition of your network if...
For reasons that completely escape me, MySQL 5.x limits UTF-8 strings to U+FFFF and smaller...
...database server your application runs on. Like MAX or COUNT, GROUP_CONCAT is a MySQL aggregation function you can use whenever your query contains a GROUP BY. You can use...
When searching for text in a MySQL table, you have two choices: The LIKE operator FULLTEXT indexes (which currently only work on MyISAM tables, but will one day work on...
...pain and you will eventually need to deal with it, probably using a non-Mysql solution...
When you work in the MySQL console and you want to see which database is used, type: SELECT database(); The result you see is the database you would activate with...
For string columns, MySQL indexes the left side of a string. That means an index can speed a like query that has a wildcard on the right side:
The next version of MySQL will include a built-in memcached daemon. This daemon can quickly get and set key/value pairs from and to InnoDB tables while completely bypassing the...
Unless you changed the default, this will be 16 MB: mysql> SHOW VARIABLES WHERE Variable_name="max_allowed_packet"; +--------------------+----------+ | Variable_name | Value | +--------------------+----------+ | max_allowed_packet...
...month / 3.0).ceil #=> 1 Yes, you do actually divide by 3.0, not 4.0. MySQL has SELECT QUARTER...
In order to open a MySQL shell without the need to enter user and password, you can say the following in any Rails 2 project: script/dbconsole -p
MySQL's MIN and MAX functions are for aggregations only. This will not work and produce an error: SELECT id, MIN(birthday, '1978-01-01') FROM users;
If you need to export data from MySQL to a CSV, you can profit from really fast built-in methods. This query writes the data to /tmp/geodb_coodinates.csv. And it's...
Use this MySQL command to show further info about a table: SHOW CREATE TABLE tags; This will output a table schema like this: CREATE TABLE `tags` ( `id` int(11) NOT...
...be useful to have a Ruby expression like condition ? positive_case : negative_case in MySQL queries: UPDATE users SET monthly_debit = IF(subscriber...