Retrieving Data - MariaDB Crash Course - page 28

▼ Analysis
SELECT DISTINCT vend_id tells MariaDB to return only distinct (unique)
vend_id rows, and so only four rows are returned, as seen in the following
output. If used, the DISTINCT keyword must be placed directly in front of the
column names.
▼ Output
+---------+
| vend_id |
+---------+
| 1001 |
| 1002 |
| 1003 |
| 1005 |
+---------+
Caution
Can't Be Partially DISTINCT The DISTINCT keyword applies to all columns, not
just the one it precedes. If you were to specify SELECT DISTINCT vend_id,
prod_price , all rows would be retrieved unless both of the specified columns were
distinct.
Limiting Results
SELECT statements return all matched rows, possibly every row in the specified
table. To return just the first row or rows, use the LIMIT clause. Here is an
example:
▼ Input
SELECT prod_name
FROM products
LIMIT 5;
▼ Analysis
The previous statement uses the SELECT statement to retrieve a single column.
LIMIT 5 instructs MariaDB to return no more than five rows. The output
from this statement is shown in the following:
▼ Output
+----------------+
| prod_name |
+----------------+