Database Management Systems
The following options can be used to delete duplicate rows in SQLite.
These examples delete duplicate rows but keep one. So if there are three identical rows for example, it deletes two of them and keeps one. This is often referred to as de-duping the table.
Continue readingThe following example returns all rows that don’t contain any numbers in PostgreSQL.
Numbers can be represented by words and other symbols, but for this article “number” simply means “numerical digit”. So we’re finding values that don’t contain any numerical digits.
Continue readingWhen using the TO_CHAR() function in Oracle Database, you can use the EEEE format element to return the number in scientific notation.
Here are four options for returning rows that contain uppercase letters in PostgreSQL.
Continue readingOracle Database provides us with the ability to return the month from a date using roman numerals.
For example, if the month is August, its decimal value would be 08 and it’s roman numeral equivalent would be VIII.
The way to do this is to use the RM or rm format element in your format mask. That will format the month using roman numerals in uppercase or lowercase respectively.
Specifying the date format can be done in several places.
Continue readingIf you think a MySQL table might have duplicate rows, you can use the following options to return all duplicates.
Continue readingIn PostgreSQL, we can use the information_schema.views view to return all views in a database.
We can also use the \dv psql command to do the same thing.
When working with MariaDB, you may occasionally find yourself needing to return all rows that don’t contain any numbers.
Technically, numbers can be represented by words and other symbols, but for this article “number” simply means “numerical digit”. So we’re finding values that don’t contain any numerical digits.
Continue readingThe modulo operation returns the remainder or signed remainder of a division, after one number is divided by another.
If you need to get the modulo of a number in MariaDB, here are three options.
Continue readingMost of the major RDBMSs have a function that enables us to return our query results as a comma separated list.
That is, we can use such a function to convert each row into a separate list item, within a comma separated list.
Below are examples of how to achieve this in some of the more popular RDBMSs.
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