Data Presentation
Learn the presentation of data through distinct, aliases, stored procedures, views, and top functions.
We'll cover the following...
All the examples below refer to the “Prod.Products” table.
Prod.Products Table
ProductID | ModVersion | Color | ModuleName | ModDescr | DatabaseIncl | UnitPrice |
1 | 1.0 | Red | Module A | Interface for using GIS maps | Yes | 1000.00 |
2 | 1.0 | Blue | Module B | Database system that allows them to enter spatial data | Yes | 1500.00 |
3 | 1.0 | Green | Module C | Email application that sends emails based on spatial preferences | No | 750.00 |
4 | 1.0 | Red | Module D | Hosting service for all modules | Yes | 2500.00 |
The DISTINCT
function
The DISTINCT
function allows us to obtain all unique values from a group of values. This function is beneficial when there are duplicates in a column in particular.
Note: We can only use the
DISTINCT
function on one column, but we can still select non-unique values from other columns after using theDISTINCT
function.
For example, the Prod.Products
table contains various product colors, and some colors appear more than once on the table. However, we’d like to gather a unique list of colors in that table. We can do that using the following syntax:
SELECT DISTINCT ColorFROM Prod.Products
We want to know which specific colors are available in the Prod.Products
table. This will output three colors as our “Prod.Products” table contains four rows with two distinct colors:
Output of DINSTINCT
Results | |
Color | |
1 | Red |
2 | Green |
3 | Blue |
Aliases
Aliases are temporary names used for tables and columns for queries within the database. They can be used to make certain columns or tables look easier to understand for the user or to keep the true identity of the column or table names a secret. It’s also beneficial to use aliases when writing complex queries, as it can simplify table and column names—thereforemaking the query-writing process quicker.
We can also create string aliases and ...