...
Mysql tutorial, mysql tutorial, mysql and java tutorial, using mysql, mysql lessons, mysql,mysql tips,mysql cheat sheet!
Sycorax - complete tutorials
Programming Tutorials
" Java provides the industry - software companies and customer alike , an opportunity to create a true open computing environment where software is portable,
and customers benefit from increase competition. "
Java and the Future
December 1, 2008-LEJB 3.1: EJB New and Improved!
The EJB 3.0 specification was a huge improvement from what you were used to in the early versions of EJB. Available as an early draft, EJB 3.1 has many more features and is even easier to use.
December 1, 2008-Should Java Assert that Network I/O Can't Occur on the UI Thread?
Doing network I/O on the user interface (UI) thread is bad. Most developers know that and can tell you why; unfortunately, it's still done.
Register now to recieve special alert and latest technology news!
Counting Rows
mysql> SELECT COUNT(*) FROM animal;
+----------+
| COUNT(*) |
+----------+
| 9 |
+----------+
Earlier, you retrieved the names of the people who owned pets. You can use COUNT() if you want to find out how many pets each owner has:
mysql> SELECT owner, COUNT(*) FROM animal GROUP BY owner;
+--------+----------+
| owner | COUNT(*) |
+--------+----------+
| Benny | 2 |
| Diane | 2 |
| Gwen | 3 |
| Harold | 2 |
+--------+----------+
Note the use of GROUP BY to group all records for each owner.
The Maximum Value for a Column
"What's the highest item number?"
SELECT MAX(article) AS article FROM shop;
+---------+
| article |
+---------+
| 4 |
+---------+
The Row Holding the Maximum of a Certain Column
Task: Find the number, dealer, and price of the most expensive article.
This is easily done with a subquery:
SELECT article, dealer, price
FROM shop
WHERE price=(SELECT MAX(price) FROM shop);
Another solution is to sort all rows descending by price and get only the first row using the MySQL-specific LIMIT clause:
SELECT article, dealer, price
FROM shop
ORDER BY price DESC