SELECT, DISTINCT, and Aliases

These commands are commonly used together to select data from a table:

SELECT: select data from a table, which is returned in a result table (the result-set)
DISTINCT: select only unique values from a field containing duplicate values
AS: give a temporary name (alias) for a selected column, often to make the output more readable

Syntax

Select all columns in the table:

SELECT * FROM table_name;

Select specific columns in the table:

SELECT <column_name1>, <column_name2>, ...
FROM <table_name>;

Select only unique values of a column:

SELECT DISTINCT(<column_name1>)
FROM <table_name>;

Select a column and temporarily rename it in the output:

SELECT <column_name1> AS <temporary_name1>, <column_name2> AS <temporary_name2>, ...
FROM <table_name>;

Select all records in the table:

SELECT * 
FROM Customers;

Displaying records 1 - 10
CustomerID	CustomerName	ContactName	Address	City	PostalCode	Country
1	Alfreds Futterkiste	Maria Anders	Obere Str. 57	Berlin	12209	Germany
2	Ana Trujillo Emparedados y helados	Ana Trujillo	Avda. de la Constitución 2222	México D.F.	5021	Mexico
3	Antonio Moreno Taquería	Antonio Moreno	Mataderos 2312	México D.F.	5023	Mexico
4	Around the Horn	Thomas Hardy	120 Hanover Sq.	London	WA1 1DP	UK
5	Berglunds snabbköp	Christina Berglund	Berguvsvägen 8	Luleå	S-958 22	Sweden
6	Blauer See Delikatessen	Hanna Moos	Forsterstr. 57	Mannheim	68306	Germany
7	Blondel père et fils	Frédérique Citeaux	24, place Kléber	Strasbourg	67000	France
8	Bólido Comidas preparadas	Martín Sommer	C/ Araquil, 67	Madrid	28023	Spain
9	Bon app’	Laurence Lebihans	12, rue des Bouchers	Marseille	13008	France
10	Bottom-Dollar Marketse	Elizabeth Lincoln	23 Tsawassen Blvd.	Tsawassen	T2F 8M4	Canada

Select the “City” column:

SELECT City 
FROM Customers;

Select all unique countries in the table:

SELECT DISTINCT Country 
FROM Customers;

Select the ID, name and postal code of customers and temporarily rename them as “IDs”, “Name” and “Postal_code”:

SELECT CustomerID AS IDs, CustomerName AS Name, PostalCode as Postal_code
FROM Customers;

Displaying records 1 - 10
IDs	Name	Postal_code
1	Alfreds Futterkiste	12209
2	Ana Trujillo Emparedados y helados	5021
3	Antonio Moreno Taquería	5023
4	Around the Horn	WA1 1DP
5	Berglunds snabbköp	S-958 22
6	Blauer See Delikatessen	68306
7	Blondel père et fils	67000
8	Bólido Comidas preparadas	28023
9	Bon app’	13008
10	Bottom-Dollar Marketse	T2F 8M4

Links to the tutorials: