Check out the following technique in MySQL if you need to find out how many days are in a month based on a given date.
DBMS
Database Management Systems
Convert a Unix Timestamp to a Date Value in Oracle
In Oracle Database, we can use the following technique to return a date from a Unix timestamp value.
The Unix timestamp (also known as Unix Epoch time, Unix time, or POSIX time) is the number of seconds that have elapsed since 00:00:00 Thursday, 1 January 1970, Coordinated Universal Time (UTC).
JSON_INSERT() vs JSON_SET() vs JSON_REPLACE() in SQLite
SQLite provides several functions for inserting, setting, and replacing values in a JSON document. Specifically, it provides json_insert(), json_set(), and json_replace().
These functions perform similar tasks, and you can sometimes use them interchangeably to a certain point.
But there is definitely a clear difference between each function.
MySQL COALESCE() Explained
In MySQL, the COALESCE() operator returns the first non-NULL value in the list, or NULL if there are no non-NULL values.
Subtract Months from a Date in PostgreSQL
In PostgreSQL, we can use the - operator to subtract one or more months from a date.
Fix “At least one of the arguments to COALESCE must be an expression that is not the NULL constant” in SQL Server
In SQL Server, if you’re getting error Msg 4127 that reads “At least one of the arguments to COALESCE must be an expression that is not the NULL constant”, it’s probably because all of your arguments to the COALESCE() expression are the NULL constant.
To fix this issue, make sure at least one argument is not the NULL constant.
2 Ways to Convert to Uppercase in Oracle
Below are two functions that convert lowercase characters to their uppercase equivalent in Oracle Database.
Both functions work in a similar way, but with a minor difference.
Detect Whether a Value Contains at Least One Numerical Digit in SQLite
The following SQLite example returns all rows that contain at least one numerical digit.
SQL Server COALESCE() Explained
In SQL Server, the COALESCE() expression returns its first non-null argument.
The way it works is, we pass a list of arguments to the expression, it evaluates the arguments in order and returns the current value of the first expression that initially doesn’t evaluate to NULL.