The SQLite changes() function returns the number of database rows that were changed, inserted or deleted by the most recently completed INSERT, DELETE, or UPDATE statement, exclusive of statements in lower-level triggers.
Basically, it allows us to see how many rows are affected when we run any of those statements.
Continue readingIn MySQL, FORMAT_BYTES() is a built in function that converts a numeric byte count to a more human-readable format. It returns a string consisting of the value and a units indicator.
We provide the numeric byte count when we call the function.
Continue readingIn MySQL, VERSION() is a built-in function that returns the MySQL server version.
The result is a string that uses the utf8mb3 character set. A suffix may also be appended to the version number indicating server build or configuration information.
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.
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.
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.
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().
In PostgreSQL, the DATE_BIN() function enables us to “bin” a timestamp into a given interval aligned with a specific origin. In other words, we can use this function to map (or force) a timestamp to the nearest specified interval.
This can be handy when we want to truncate a timestamp to a given interval, for example a 10 minute interval. We can specify the interval (e.g. 10 minutes, 15 minutes, 30 minutes, etc), and we can specify the starting point for the interval. Therefore, we can have the interval starting at any odd time we want (it doesn’t need to start on the hour or anything like that).
Continue readingIn MariaDB, the NVL2() function allows us to replace a value with another value, the new value being determined by whether or not the initial value is null.
It’s similar to the NVL() function, except that NVL2() accepts three arguments instead of two. This allows us to specify a different value to return in the event the first argument is not null.
Some DBMSs have an NVL2() function that allows us to replace a value with another value, the new value being determined by whether or not the initial value is null.
It’s similar to the NVL() function, except that NVL2() accepts exactly three arguments. This allows us to specify a different value to return in the event the first argument is not null.
In contrast, with the NVL() function, some DBMSs accept only two arguments (which makes the function a synonym for the IFNULL() function) while others accept an unlimited number of arguments (which makes it a synonym for the COALESCE() function).