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

The UNION Operator is used to combine the result set of two or more SELECT Statement. This operator is useful if you have two table that share the same column name and data type and you want to combine it in a single Query.

Take note that both table must have the same column name and data type.

The DEFAULT Constraint is used to insert the default values into a column during design time.

The default values is used in new record if no value is specified during INSERT Statement.

The default

SQL DEFAULT Constraint Syntax

COUNT is a simple aggregate function provided by SQL. As it is clear from its name that it simply counts the number of records in the table and returns the total count.

There are three (3) different usage for the Count function.

• SQL COUNT(column_name)
• COUNT(*)
• COUNT(DISTINCT column_name)

Consider the following table for this exercise

Employess

The data type determines the kind of values that users can store in the field. Like every programming languages, the SQL also has specific data type to store data. Following are some data type and there descriptions in which SQL allows us to store data.

Microsoft Access Data Types

Source: Microsoft Access Help