In MySQL, DATABASE() is a built-in function that returns the default (current) database name.
The result is returned as a string in the utf8 character set. If there is no default database, it returns NULL.
MySQL
SUM() Function in MySQL
In MySQL, the SUM() aggregate function returns the sum of a given expression.
It can also be used to return the sum of all distinct (unique) values in an expression.
How to Add an Option to sql_mode in MySQL Without Losing Existing Settings
Here are two options we can use to add an option to our sql_mode without wiping all existing options.
SQL LPAD()
In SQL, LPAD()is a commonly used function that pads the left part of a string with a specified character. The function can be used on strings and numbers, although depending on the DBMS, numbers may have to be passed as a string before they can be padded.
DBMSs that have an LPAD() function include MySQL, MariaDB, PostgreSQL, and Oracle.
DBMSs that don’t have an LPAD() function include SQL Server and SQLite (although there are other ways to apply left padding in these DBMSs).
SQL RPAD()
In SQL, RPAD()is used to pad the right part of a string with a specified character. The function can be used on strings and numbers, although depending on the DBMS, numbers may have to be passed as a string before they can be padded.
DBMSs that have an RPAD() function include MySQL, MariaDB, PostgreSQL, and Oracle.
DBMSs that don’t have an RPAD() function include SQL Server and SQLite.
DROP TABLE IF EXISTS in MySQL
In MySQL, we can use the IF EXISTS clause of the DROP TABLE statement to check whether the table exists or not before dropping it.
Format a Number as Currency in SQL
Some DBMSs have functions that allow us to format numbers as currency just by passing the appropriate format string. This converts the number to a string with the applicable currency symbol, group separator, and decimal point (if relevant).
Other DBMSs don’t make it that easy, and you need to do a bit of work first.
Below are examples of using SQL to format numbers as currency in some of the most popular DBMSs.