SQL-practicing
This course uses SQL-Trainer facility for practicing SQL-queries and update operations.
SQL-Trainer provides a web user interface for carrying out operations on an example database.
This course uses pizza taxi database.
Tables are named in English. You may inspect the structure of the database as a
schema diagram or as SQL
create table statements. You get the description of the database also thru the
trainig software. SQL-Trainer presents you the tasks to be solved.
To start the SQL-Trainer fill the login form at the end
of this page.
Instructions
Registration and login
Answers
- Tasks have been split into groups each with a deadline. You get credits if you
are able to solve the task before the deadline. SQL-Trainer shows
which tasks you have already solved. It does not, however, show how many tasks have brought
in credits.
- You may try to solve a task as many times as you like.
The number of tries does not affect the credits.
The first task 'free practicing' is intented for trying your own queries.
There are less checks done for that task.
- If you get Internal server error -messages, the reason may be
- Problems in database connections,
- Database or application server is down,
- Some error in Trainer software
Please, report these errors to laine@cs.helsinki.fi.
- If the program just seems to do nothing after you have
delivered a query, your query is probably very large, i.e. it retrieves a lot of rows.
This may be due to missing join conditions.
Although the example tables are small, you might get very large results, if you forget the join
conditions. Currently there are no means to cancel a query.
If you get into this situation, just wait and do not try again before you have considered
changing the query.
Hints
- Dates may be given in Finnish standard format (dd.mm.yyyy for example 21.8.2001) and
in American style (DD-MON-YYYY, for example 21-AUG-2001).
- Some error messages are given by the dbms. They contain an error number in the beginning.
Oracle manual on error messages may give some advise on how to find the error.
- You may build your queries by starting with a simple query and the adding tables and
conditions to obtain the final query.
Starting SQL-Trainer
First connect: Pick any user id (user accout, lastname, nicname,...),
no password needed
Deadline for SQL-summary queries
moved to 24.2.2004 at 23.59