The SELECT statement has five main clauses to choose from, although, FROM is the only required clause. Each of the clauses have a vast selection of options, parameters, etc. The clauses will be listed below, but each of them will be covered in more detail later in the tutorial.
Here is the format of the SELECT statement:
SELECT [ALL | DISTINCT] column1[,column2]
[GROUP BY “column-list”]
[ORDER BY “column-list” [ASC | DESC] ]
SELECT * FROM table_name
The DISTINCT clause allows you to remove duplicates from the result set. The DISTINCT clause can only be used with select statements.
The syntax for the DISTINCT clause is:
SELECT DISTINCT columns FROM tables WHERE predicates;
Let’s take a look at a very simple example.
SELECT DISTINCT city
This SQL statement would return all unique cities from the suppliers table.
The DISTINCT clause can be used with more than one field.
SELECT DISTINCT city, state
This select statement would return each unique city and state combination. In this case, the distinct applies to each field listed after the DISTINCT keyword.