The following table contains a full list of format specifiers that can be used in format strings with functions like DATE_FORMAT(), STR_TO_DATE(), and FROM_UNIXTIME() in MySQL.
Author: Ian
How to Create a Repeating Sequence in SQL Server
When we create a sequence object in SQL Server, we have the option of making it a repeating sequence or a nonrepeating sequence. By repeating I mean, we can have the sequence continually start again once the min/max value has been reached. In other words, we can have the sequence reiterate over and over again.
We can do this with the CYCLE argument.
Fix “WRONGTYPE Operation against a key holding the wrong kind of value” when Setting a Hash in Redis
If you get an error that reads “WRONGTYPE Operation against a key holding the wrong kind of value” when setting a hash with a command like HSET or HSETNX, it’s probably because you’re trying to set a non-hash key that already exists. In other words, the key already exists, but it doesn’t contain a hash.
To fix this issue, be sure to use these commands on keys that either don’t already exist, or contain a hash.
Continue readingMySQL SESSION_USER() Explained
In MySQL, SESSION_USER() is a synonym for the USER() function. It returns the current MySQL user name and host name, given when connecting to MySQL.
MySQL SYSTEM_USER() Explained
In MySQL, SYSTEM_USER() is a synonym for the USER() function. It returns the current MySQL user name and host name, given when connecting to MySQL.
How to Set Up Named Time Zones in MySQL
If you want to use named time zones in MySQL, you’ll need to make sure they’ve been configured.
By “named time zones”, I mean being able to use strings like US/Eastern instead of −04:00 or −05:00 when specifying the time zone. For example, when using the CONVERT_TZ() function.
Here’s how to configure named time zones in MySQL.
Continue readingFix ERROR 1045: “Access denied for user…” in MySQL
If you’re getting error 1045 that reads something like “Access denied for user ‘root’@’localhost’“, it’s because you’re trying to log in to MySQL without the right credentials.
This usually happens when we provide the wrong password. But there could also be another cause. For example, we could be trying to do something as the root user that requires a password, but the root user hasn’t yet had its password set.
To fix this issue, be sure to provide the correct password when connecting to MySQL.
Continue readingMySQL CURRENT_USER() Explained
In MySQL, CURRENT_USER() is a built-in function that returns the user name and host name combination for the MySQL account that the server used to authenticate the current client.
MySQL USER() Explained
In MySQL, USER() is a built-in function that returns the current MySQL user name and host name, given when connecting to MySQL.
The result is returned as a string in the utf8mb3 character set.
The value returned by USER() could be different to the value returned by CURRENT_USER().
How to Include Elements that Contain NULL Values When Using FOR XML in SQL Server
When using FOR XML in SQL Server, we can use the ELEMENTS directive to include a column as an element instead of an attribute. However by default, if a column contains a NULL value, no element is produced for that column in the resulting XML document. This may or may not be what we want, depending on the requirements.
If we want such columns to be included in the XML even when they contain NULL values, all we need to do is include the XSINIL option. This option specifies that any column that has a NULL value automatically gets an element with xsi:nil="true" in the resulting XML.
The alternative is ABSENT, which means columns with NULL values are excluded (this is the default behaviour).