If you ever need to use SQL to return just the numeric values in a character column, the method you use will largely depend on your DBMS. Most DBMSs support regular expressions (regex), but some don’t. And some include functions that can detect numeric values.
Here are examples of how to do it in the more popular DBMSs.
Continue readingWhen we have a table with a generated column, here are two methods we can use to return its definition.
Continue readingMost RDBMSs provide at least a few ways to return rows that contain uppercase characters. Here are some options available in the major RDBMSs.
Continue readingBelow are examples of using SQL to return the last day of the month across various DBMSs.
This could be the last day of the current month, or the last day of a month based on a given date.
Continue readingIn SQLite we can use the lower() function to convert uppercase characters to lowercase.
Here are examples of using SQL to return duplicate rows when those rows have a primary key or other unique identifier column.
These queries work in most of the major RDBMSs, including SQL Server, Oracle, MySQL, MariaDB, PostgreSQL, and SQLite.
Continue readingIn 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.
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 readingHere’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 readingHere 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 reading