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.
SQL DISTINCT >>
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