Working with SQL is pretty straight forward. Once can easily parse xml, json, or just csv and insert values into new rows in a database. Here, we’ll insert two fields, user_name and role_name into a new row in a table called krypted: INSERT INTO krypted (user_name, role_name) VALUES (krypteduser, admingroup);
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Install mySQL on macOS
macOS might be the easiest platform to install MySQL on. To do so, simply download the MySQL installation package from the MySQL Download site. I like to use the third link (the DMG). Once downloaded, run the package. The package will ask you a few questions and you can easily just select the default choice during the installation process. Once installed, you’ll be prompted that a temporary password has been used for your MySQL instance. The password will get you in the first time, so you can change it. Once you have documented the password, open System Preferences and click on MySQL in the bottom row of System Preference Panes. Click Start MySQL…
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Show MySQL Settings
MySQL usually pulls settings from a my.cnf file. However, you can end up with settings in include files, which can be defined in the my.cnf using the following directives: include /home/mydir/myopt.cnf includedir /home/mydir Because of this, and the fact that you might not have access to all locations of .cnf files on a filesystem, you can also grab them using the SHOW VARIABLES option within SQL, obtained by /usr/local/mysql/bin/mysql -uroot -p mypassword -e "SHOW VARIABLES;" > /tmp/SQLSettings.txt In the above command, -uroot defines we’ll be accessing with the root user, -p defines the password (listed as mypassword) and the -e defines that we want to execute a command and then…
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mysql command switches
Mysql command options: –auto-rehash Enable or disable automatic rehashing –auto-vertical-output Automatically display output of commands vertically rather than horizontally –batch Do not write to the history file –binary I use this when I have large results timing out due to blobs being in there –bind-address Specify a network interface when connecting to the server –character-sets-dir Indicate a custom directory where character sets are installed –column-names Output column names when running queries –column-type-info Show metadata –comments Enable or disable commenting when sending statements to the server –compress Compresses data sent to/from client and server –connect_timeout Seconds of inactivity before a timeout –database The database to connect to –debug Write debugging log; supported only if MySQL was built with debugging support –debug-check Print debugging information…
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Use the Slow Query Log in MySQL
Slow queries can cause poor database performance. MySQL has a slow query log, which lets you log queries that take too long (with too long a user-configurable setting). This allows you to quickly find craptastic queries in your logs. To enable the slow query log, use SET GLOBAL and then set the slow_query_log option to ON: SET GLOBAL slow_query_log = 'ON'; By default, the slow query log identifies any query that takes 10 seconds or longer. To change long_query_time using SET GLOBAL. Here, we’ll set it to 7 seconds: SET GLOBAL long_query_time = 7; You can also set the log file to something other than the default location of /var/lib/mysql/hostname-slow.log.…
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Index Those SQL Tables
If you have growing sets of data, one of the best ways to speed up database performance is to make sure each column in larger tables is indexed. You can easily index a column following this syntax (using the name of your table in the place of tablename and the name of your column in the place of columnname): ALTER TABLE tablename ADD INDEX (columnname); So if you have a table called Customers and the following columns (as in the case of my Customers database from the previous exercises): ID Site Contact Address City Zip Country You would index them all as follows: ALTER TABLE Customers ADD INDEX (ID); ALTER…
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SQL and Date Functions
SQL has some really great features for managing dates. Given that dates are a very common thing to store in databases, that’s a pretty logical thing to get to a good, mature point. But the most challenging aspect of working with date and time in SQL is formatting. There are lots of different ways to format dates around the world, and even different structures (e.g. epoch) that are often complicated by adding time to records. But, you need to do things in a consistent fashion with how SQL expects them, if you’ll be using built in functions to manage dates. Dates can be stored in a variety of formats, which…
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Allow Remote Connections To MySQL
By default, MySQL allows other services on the computer you’re running the daemon to connect to the database and denies any connections from hosts outside that computer. However, it’s pretty easy to provide access to the database from another host (for example, if you’re splitting up the back-end and front-end of a site, clustering, etc. To get started, you’ll edit your my.cnf file and find the [mysqld] section of the file. Then, locate the bind-address, which you will need to set as the IP of your server and comment out the line for skip-networking. Let’s say we’re going to open access for 192.168.2.2. The section would look similar to the…
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SQL TOP
No, SQL top doesn’t look at the status of a database the way the TOP command in bash does. It looks at the top number of records returned in a query, so a bit more like head. This makes SELECT TOP useful with larger tables where this will be millions of records getting loaded into memory during a query. In this article, we’ll use the same “Customers” table from our first articles to test out TOP: ID Site Contact Address City Zip Country 1 Krypted Charles Edge my house Minneapolis 55418 US 2 Apple Tim Cook spaceship Cupertino 95014 US 3 Microsoft Satya Nadella campus Redmond 98053 US 4 Facebook…
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Reset A Lost MySQL Password
The first step to reset a password is to stop the MySQL daemon. This will cause mysqld to accept no new connections and terminate existing connections. But this can all be done in a matter of seconds, usually. To stop MySQL on Mac, use the System Preference pane or launchctl. To stop on Linux, use init.d: sudo /etc/init.d/mysql stop Or if it’s mysqld instead: sudo /etc/init.d/mysqld stop Then start the SQL daemon using the –skip-grant-tables option: sudo mysqld_safe --skip-grant-tables & Next, login to mysql, which won’t require a password running in this mode: mysql -u root And use the UPDATE USER statement to set a new password: UPDATE USER set…