Here are three examples that use SQL to find and select the row with the maximum value in a given column.
The examples work in most major RDBMSs, including MySQL, MariaDB, PostgreSQL, SQLite, Oracle, and SQL Server.
Continue readingAuthor: Ian
4 Ways to Select Duplicate Rows in PostgreSQL
If you have a table with duplicate rows in PostgreSQL, you can use any of the following queries to return the duplicate rows.
Continue reading2 Ways to Return Rows that Contain Only Alphanumeric Characters in Oracle
Below are two methods for returning rows that only contain alphanumeric characters in Oracle Database.
Alphanumeric characters are alphabetic characters and numeric characters.
Continue reading4 Ways to List All Views in a MariaDB Database
Below are four ways to list out the views in a MariaDB database using SQL or the command line.
Continue reading4 Ways to Check if a Table Exists Before Dropping it in SQL Server (T-SQL)
Dropping a table in SQL easy. You simply use DROP TABLE myTable where myTable is the name of the table you want to drop. You can use this method to drop a table in SQL Server via T-SQL script.
But you’ll get an error if the table doesn’t actually exist. That is, unless you check for the existence of the table first.
Below are four ways of using T-SQL to check whether the table exists before dropping it.
Continue reading2 Ways to Delete Duplicate Rows in SQLite
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 readingFind Values That Don’t Contain Numbers in PostgreSQL
The 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 readingHow to Format Numbers in Scientific Notation in Oracle
When using the TO_CHAR() function in Oracle Database, you can use the EEEE format element to return the number in scientific notation.
4 Ways to Find Rows that Contain Uppercase Characters in PostgreSQL
Here are four options for returning rows that contain uppercase letters in PostgreSQL.
Continue readingHow to Format the Month in Roman Numerals in Oracle
Oracle 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.
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