====== Information about MySQL RDBMS ======

===== Connection =====
  * You've obtained the credentials via e-mail. If not, contact your practical course lecturer.
  * In order to connect (and use the database) interactively,
    - Log in via SSH to the MySQL server: <code>ssh login@147.32.84.109</code>
    - At the prompt use the mysql command: <code>mysql --user=login --password=SECRET --database=login</code>
  * <fc #FF0000>Warning:</fc> The access to the MySQL server is allowed only locally, therefore you cannot connect to the database remotely (by specifying the '' --host'' parameter).


===== Use in the BASH script =====
You can also use the mysql command in batch mode (provided the ''student'' table 
exists). This approach was needed for D-tasks before year 2015.

<code>
MYSQL_LOGIN_PARAMS=" --user=login --password=SECRET --database=login "
MYSQL_PARAMS=" --skip-column-names "
MYSQL_SQL_QUERY='SELECT * FROM student;'


mysql ${MYSQL_LOGIN_PARAMS} ${MYSQL_PARAMS} --execute="${MYSQL_SQL_QUERY}" \
  | while read i ; do 
      echo $i ; 
    done

</code>
===== An example database =====
Download and play with the [[http://labe.felk.cvut.cz/~stepan/33OSD/files/world.sql|world.sql]] database export.

Try the following examples:

  - //Simple query//
    - Find cities with population greater than 8 mil. people.
    - Sort the previous results by population size.
  - //Query with join//
    - Print a list of countries with population above 60 mil. together with name and population of their capital. Sort by country population (descending).
    - Where appropriate, rename the attribute names in the resulting table in the query above.
  - //Query using with multiple JOIN//
    - List all capitals where the official language is dutch.
  - //Query with aggregation -- GROUP BY/HAVING//
    - List all languages that are official languages in more than one country. List them together with number of countries an sort them by the count.
  - List all cities (and countries) where at least 50 % inhabitants speak dutch.
  - Find a country with the smallest area
    - Solve the same query with a sub-query.
  - Find the area of Europe (i.e. sum of areas of all european countries)
  - Find continents with the smallest and greatest population (alternatively, list all and order by population).
  - List all continents where average life time is greater than 70 yrs.
    - What is an average life time in czech speaking countries?
  - List all countries that have more than one language being spoken by at least 30 % inhabitants.