SQL-SELECT Command

The most commonly used SQL command is SELECT statement. The SQL SELECT statement is used to query or retrieve data from a table in the database. A query may retrieve information from specified columns or from all of the columns in the table. To create a simple SQL SELECT Statement, you must specify the column(s) name and the table name. The whole query is called SQL SELECT Statement.

Syntax of SQL SELECT Statement:

SELECT column_list FROM table-name
[WHERE Clause]
[GROUP BY clause]
[HAVING clause]
[ORDER BY clause];

 table-name is the name of the table from which the information is retrieved.

·         column_list includes one or more columns from which data is retrieved.

·         The code within the brackets is optional.

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·         The SELECT statement allows you to retrieve records from one or more tables in your database.

·         The syntax for the SELECT statement is:

·         SELECT columns
FROM tables
WHERE predicates;

        

·         Example #1

·         Let's take a look at how to select all fields from a table.

·         SELECT *
FROM suppliers
WHERE city = 'Newark';

·         In our example, we've used * to signify that we wish to view all fields from the suppliers table where the supplier resides in Newark.

          

·         Example #2

·         You can also choose to select individual fields as opposed to all fields in the table.

·         For example:

·         SELECT name, city, state
FROM suppliers
WHERE supplier_id > 1000;

·         This select statement would return all name, city, and state values from the suppliers table where the supplier_id value is greater than 1000.

         

·         Example #3

·         You can also use the select statement to retrieve fields from multiple tables.

·         SELECT orders.order_id, suppliers.name
FROM suppliers, orders
WHERE suppliers.supplier_id = orders.supplier_id;

The result set would display the order_id and suppier name fields where the supplier_id value existed in both the suppliers and orders table