This article contains an example of adding a generated column to a table in MySQL.
Also known as computed columns, generated columns usually contain values that are dependent on other factors (such as the values in other columns).
Creating (or adding) a generated column in MySQL is basically the same as creating a normal column, except that the definition of the generated column contains an expression that determines the column’s value.
Here are three methods we can use to return the first day of a given month in MySQL.
This could be the first day of the current month, or the first day of the month based on a date that we specify.
Getting the first day of the month allows us to perform further calculations on the resulting date, like adding a certain number of days to the start of the month, etc.
In SQLite, we can use the TIME() function to add a given number of seconds to a time value.
If we’re dealing with datetime values, we can use the DATETIME() function.
Below are two options for removing duplicate rows from a table in PostgreSQL when those rows have a primary key or unique identifier column. The primary key is used in the query, but it’s ignored when comparing duplicates (due to the fact that primary keys prevent duplicate rows by definition).
The following examples delete duplicate rows but keep one. So in the case of say, three identical rows, it deletes two and keeps one.
In PostgreSQL, we can use the - operator to subtract one or more hours from a time value.
By “time” value, this could be an actual time value, a timestamp, or an interval. We can also subtract hours from a date value or a date and time combination.
Below are two Oracle Database functions that convert uppercase characters to their lowercase equivalent.
Here are four options for returning rows that contain lowercase characters in PostgreSQL.
Here are two options for returning the number of days in a given month in SQLite. This could be the number of days in the current month, or it could be based on a given date.