Tag Archives: database
SQL JOINing a Table to Itself
Consider that tried-and-tested example: employees and managers. Here's the staff
table from the database (today's imaginary data isn't particularly imaginative, sorry):
mysql> select * from staff; +----+------------+-----------+------------+ | id | first_name | last_name | manager_id | +----+------------+-----------+------------+ | 1 | Hattie | Hopkins | 4 | | 2 | Henry | Hopkins | 4 | | 3 | Harry | Hopkins | 5 | | 4 | Helen | Hopkins | NULL | | 5 | Heidi | Hopkins | 4 | | 6 | Hazel | Hopkins | 1 | +----+------------+-----------+------------+ 6 rows in set (0.00 sec)
Inner vs Outer Joins on a Many-To-Many Relationship
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Importing and Exporting MongoDB Databases
mysqldump
for mongodb?
It should have come as no surprise that the command I wanted was called mongodump
, really! Continue reading
Explaining MySQL's EXPLAIN
Handling SQL Errors in PDO
Simple CRUD with MongoDB
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Script for Database Patching at Deploy Time
My current project (BiteStats, a simple report of your google analytics data) uses a basic system where there are numbered patches, and a patch_history
table with a row for every patch that was run, showing the version number and a timestamp. When I deploy the code to production, I have a script that runs automatically to apply the patches.
Is Enum Evil?
There are cases where an enum is the correct choice for a particular type of data, so let's look at what an enum type actually is and does.
Indexes on Tables
Too often though, they don't think about how that data will be retrieved or what the implications are when it gets beyond the thousand records that were used for testing. This is where having an idea of how the data will be retrieved can really help application performance. (note: this article is aimed at users of traditional relational databases, and ignores all other possibilities). This post takes a look at the various index types and when to use them. Continue reading