The MIN function is use to return the smallest value of the selected column. MIN can be use only in numeric column.

As with other function, you can also give an Alias to the MIN function.

SQL MIN() Syntax

The SUM function is an aggregate function use to calculate the total amount of a column. SUM function can be use only in numeric column.

Syntax

The NOW() function is an aggregate function used to return the date and time along with other column.

The NOW() function returns the result as dd/mm/yyyy HH:MM:SS AM/PM depending on your regional settings.

SQL NOW() Syntax

The LEN function is useful to count the number of characters in a column you specified as the parameter. LEN is short for length. The LEN function returns the number of characters including spaces or any character within that column.

You can use SQL Alias to name the result of the LEN function.

SQL LEN() Syntax

The FORMAT() function is normally applied on formatting column with Date value like YYYY, MM, and DD.

SQL FORMAT() Syntax

The UNIQUE Contraints identifies a record in a database table uniquely. Unlike PRIMARY KEY contraints, you can have many UNIQUE contraint in a table.

UNIQUE Contraints Syntax - MySQL