Here are a couple of ways to show a list of databases when using psql with PostgreSQL.
The first option can be used when we’re already connected to PostgreSQL. The second option can be used when we don’t currently have a connection to Postgres.
DBMS
Database Management Systems
Add Days to a Date in SQLite
In SQLite, we can use the DATE() function to add a given number of days to a date.
If we’re dealing with datetime values, we can use the DATETIME() function.
nullvalue: Show NULL Values in SQLite
When using the SQLite command line interface (CLI), by default, whenever a query returns a null value, the output is the empty string ('').
We can change this by using the -nullvalue command line option when launching SQLite.
We can also use the .nullvalue dot command if we’re already in the SQLite CLI.
JSON Functions & Operators in SQLite (Full List)
Below is a full list of JSON functions and JSON operators available in SQLite.
How to Detect if a Value Contains at Least One Numerical Digit in MariaDB
When working with MariaDB, you may occasionally find yourself needing to return all rows that contain at least one numerical digit.
In such cases, you may find the following example useful.
2 Ways to Return the Julian Day in SQLite
Here are two methods for returning the Julian Day in SQLite.
The Julian Day is the fractional number of days since noon in Greenwich on November 24, 4714 B.C. It’s the continuous count of days since the beginning of the Julian period, and is used primarily by astronomers, and in software for easily calculating elapsed days between two events.
SQLite ->> Operator
In SQLite, the ->> operator extracts a subcomponent from a JSON document and returns an SQL representation of that subcomponent.
The ->> operator was first introduced in SQLite version 3.38.0 (released on 22 February 2022).
SQLite -> Operator
In SQLite, the -> operator extracts a subcomponent from a JSON document and returns a JSON representation of that subcomponent.
The -> operator was first introduced in SQLite version 3.38.0 (released on 22 February 2022).