In SQLite, we can use the DATE() function to add one or more years to a date.
For datetime values, we can use the DATETIME() function.
Tag: how to
Find Rows that Contain Lowercase Characters in SQL
Most RDBMSs provide at least a few ways to return rows that contain lowercase characters. Here are some options available in the major RDBMSs.
Continue readingHow to Create a Generated Column in PostgreSQL
In PostgreSQL, a generated column is a special column that is always computed from other columns. A generated column doesn’t have a fixed value like in a base column. Rather, its value is determined by an expression that references other columns in the table.
Generated columns are included in the SQL standard (ISO/IEC 9075), and are supported by most major RDBMSs. Generated columns were first introduced in PostgreSQL 12.
Continue readingSelect Duplicate Rows in SQL
Here’s an example of using SQL to find duplicate rows in a database table. This technique can be used in most of the major RDBMSs, including SQL Server, Oracle, MySQL, MariaDB, PostgreSQL, and SQLite.
Continue reading2 Ways to Get the Definition of a Generated Column in MySQL
A generated column is one whose value is derived from an expression, as opposed to a fixed value. The expression typically uses other columns in the same table to compute the derived value.
We can create a generated column in MySQL very easily. But what if we want to go back later and see its definition?
Here are two options for returning the definition of a generated column in MySQL.
Continue readingHow to Convert a Unix Timestamp to a Date/Time in SQL
Here are examples of converting a Unix timestamp to a date/time value in some of the major RDBMSs.
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).
Continue readingSubtract Minutes from a Time Value in SQLite
In SQLite, we can use the TIME() function to subtract one or more minutes from a time value.
For datetime values, we can use the DATETIME() function.
Create a Generated Column in MySQL
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.
Continue readingReturn Rows that Contain Only Alphanumeric Characters in SQL
Alphanumeric characters are alphabetic characters and numeric characters.
Below are examples of using SQL to return rows that contain only alphanumeric characters.
Continue reading3 Ways to Get the First Day of the Month in MySQL
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.
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