Monday, November 5, 2007

SQL SELECT

What do we use SQL commands for? A common use is to select data from the tables located in a database. Immediately, we see two keywords: we need to SELECT information FROM a table. (Note that a table is a container that resides in the database where the data is stored. For more information about how to manipulate tables, go to the Table Manipulation Section). Hence we have the most basic SQL structure:

SELECT "column_name" FROM "table_name"

To illustrate the above example, assume that we have the following table:

Table Store_Information

store_name Sales Date
Los Angeles $1500 Jan-05-1999
San Diego $250 Jan-07-1999
Los Angeles $300 Jan-08-1999
Boston $700 Jan-08-1999

We shall use this table as an example throughout the tutorial (this table will appear in all sections). To select all the stores in this table, we key in,

SELECT store_name FROM Store_Information

Result:

store_name
Los Angeles
San Diego
Los Angeles
Boston

Multiple column names can be selected, as well as multiple table names.

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