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.
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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.
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.
Subtract Years from a Date in PostgreSQL
In PostgreSQL, we can use the - operator to subtract one or more years from a date.
Fix “ERROR 1136 (21S01): Column count doesn’t match value count at row 1” when Inserting Data in MariaDB
If you find yourself getting an error that reads something like “ERROR 1136 (21S01): Column count doesn’t match value count at row” in MariaDB, it’s probably because you’ve specified the wrong number of expressions for the number of columns in the column when attempting to insert data into a table.
In other words, you’re trying to insert too many columns or not enough columns.
7 Ways to Return Duplicate Rows that have a Primary Key in MariaDB
Here are seven ways to return duplicate rows in MariaDB when those rows have a primary key or other unique identifier column.
Therefore, the duplicate rows share exactly the same values across all columns except for their unique identifier column.
Detect Whether a Value Contains at Least One Numerical Digit in PostgreSQL
The following example returns all rows that contain at least one numerical digit in PostgreSQL.