Relational Databases
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General information
ssh reldb@gks-virt(050-061).scc.kit.edu -p24
Session 1 - Setup
$ mysql -u root
mysql> show databases; mysql> create database playground; mysql> show databases;
CTRL-D
$ sudo ls -la /var/lib/mysql/ $ sudo ls -la /var/lib/mysql/playground $ sudo ls -la /var/lib/mysql/mysql
$ mysql -u root
mysql> use mysql; mysql> show tables;
mysql> select * from user; mysql> create user 'joffrey' identified by 'kings_landing'; mysql> create user 'joffrey'@'localhost' identified by 'kings_landing'; mysql> create user 'hodor' identified by 'hodor'; mysql> create user 'hodor'@'localhost' identified by 'hodor'; mysql> select * from user;
mysql> drop user 'joffrey'; mysql> drop user 'hodor';
mysql> select * from user;
CTRL-D
$ mysql -u hodor -p
mysql> use playground;
CTRL-D
$ mysql -u root
mysql> show grants; mysql> grant all privileges on playground.* to 'joffrey'@'localhost';
CTRL-D
$ mysql -u joffrey
mysql> show grants;
CTRL-D
Session 2 - CRUD
$ mysql -u joffrey -p
mysql> use playground;
mysql> show engines;
mysql> create table persons ( name varchar(256), gender char(1) ) engine=innodb;
mysql> describe persons;
mysql> insert into persons (name, gender) values ('Eddard Stark', 'm'); insert into persons (name, gender) values ('Catelyn Stark', 'f'); insert into persons (name, gender) values ('Robb Stark', 'm'); insert into persons (name, gender) values ('Jon Snow', 'm'); insert into persons (name, gender) values ('Arya Stark', 'f'); insert into persons (name, gender) values ('Tywin Lannister', 'm'); insert into persons (name, gender) values ('Cersei Lannister', 'f'); insert into persons (name, gender) values ('Jaime Lannister', 'm'); insert into persons (name, gender) values ('Joffrey Baratheon', 'm'); insert into persons (name, gender) values ('Tyrion Lannister', 'm'); insert into persons (name, gender) values ('Daenerys Targaryen', 'f'); insert into persons (name, gender) values ('Hodor', 'm'); insert into persons (name, gender) values ('Ygritte', 'f');
mysql> select * from persons;
mysql> select * from persons where gender='m';
mysql> select gender from persons where name='Hodor';
mysql> select gender, count(*) from persons group by gender;
mysql> select * from persons where name like '%Stark';
mysql> select substring_index(name, ' ', 1) from persons;
mysql> select substring_index(name, ' ', -1) from persons;
mysql> create table persons_2 ( first_name varchar(128), last_name varchar(128), noble_house varchar(128), gender char(1) ) engine=innodb;
mysql> select substring_index(name, ' ', 1) as first_name, substring_index(name, ' ', -1) as last_name, gender from persons;
mysql> insert into persons_2 select substring_index(name, ' ', 1) as first_name, substring_index(name, ' ', -1) as last_name, gender from persons;
mysql> insert into persons_2 (first_name, last_name, noble_house, gender) select substring_index(name, ' ', 1) as first_name, substring_index(name, ' ', -1) as last_name, substring_index(name, ' ', -1) as noble_house, gender from persons;
mysql> drop table persons;
mysql> alter table persons_2 rename persons;
mysql> select * from persons;
mysql> update persons set noble_house='Stark' where last_name='Snow';
mysql> update persons set noble_house='Lannister' where last_name='Baratheon';
mysql> update persons set last_name=NULL, noble_house=NULL where first_name in ('Hodor', 'Ygritte');
mysql> select first_name from persons where noble_house='Stark' and gender='f';
mysql> select noble_house, count(*) as members from persons group by noble_house order by members desc;
mysql> delete from persons where first_name='Joffrey';
Session 3 - Relations
$ mysql -u joffrey -p
mysql> use playground;
mysql> create table locations ( name varchar(256), owner varchar(256) ) engine=innodb;
mysql> insert into locations (name, owner) values ('Winterfell', 'Stark'); insert into locations (name, owner) values ('Casterly Rock', 'Lannister'); insert into locations (name, owner) values ('Kings Landing', 'Targaryen'); insert into locations (name, owner) values ('Nights Watch', 'The Wall'); insert into locations (name, owner) values ('Beyond the Wall', NULL);
mysql> select * from persons, locations;
mysql> select * from persons p, locations l where p.noble_house = l.owner;
mysql> select p.first_name, p.last_name, l.name from persons p, locations l where p.noble_house = l.owner;
mysql> select p.first_name, p.last_name, l.name from persons p left join locations l on p.noble_house = l.owner;
mysql> select p.first_name, p.last_name, l.name from persons p right join locations l on p.noble_house = l.owner;
mysql> select p1.first_name, p2.first_name from persons p1, persons p2 where ((p1.gender='m' and p2.gender='f') and (p1.noble_house != p2.noble_house));
mysql> create table forces ( owner varchar(256), location varchar(256), swordmen int, archers int, catapults int ) engine=innodb;
mysql> insert into forces (owner, location, swordmen, archers, catapults) values ('Stark', 'Winterfell', 1000, 1000, 10); insert into forces (owner, location, swordmen, archers, catapults) values ('Lannister', 'Casterly Rock', 1000, 1000, 10); insert into forces (owner, location, swordmen, archers, catapults) values ('Targaryen', 'Kings Landing', 1000, 1000, 10); insert into forces (owner, location, swordmen, archers, catapults) values (NULL, 'Beyond the Wall', 1000, 1000, 10); mysql> select * from persons, locations, forces;
mysql> select p.noble_house as family, l.name as headquarter, f.location as battlefield, f.swordmen, f.archers, f.catapults from persons p, locations l, forces f where p.noble_house = l.owner and l.owner = f.owner;
mysql> select distinct noble_house from persons;
mysql> select p.noble_house as family, l.name as headquarter, f.location as battlefield, f.swordmen, f.archers, f.catapults from (select distinct noble_house from persons) p, locations l, forces f where p.noble_house = l.owner and l.owner = f.owner;
mysql> insert into forces (owner, location, swordmen, archers, catapults) values ('Stark', 'Casterly Rock', 300, 10, 1);
mysql> create view battleground as select p.noble_house as family, l.name as headquarter, f.location as battlefield, f.swordmen, f.archers, f.catapults from (select distinct noble_house from persons) p, locations l, forces f where p.noble_house = l.owner and l.owner = f.owner;
mysql> create view noble_houses as select distinct noble_house from persons;
mysql> create view battleground as select p.noble_house as family, l.name as headquarter, f.location as battlefield, f.swordmen, f.archers, f.catapults from noble_houses p, locations l, forces f where p.noble_house = l.owner and l.owner = f.owner;
mysql> select b1.* from battleground b1, battleground b2 where b1.family != b2.family and b1.battlefield = b2.battlefield;
mysql> create view battle as ( select b1.* from battleground b1, battleground b2 where b1.family != b2.family and b1.battlefield = b2.battlefield );
mysql> create view strength as select family, swordmen*1+archers*2+catapults*10 as battle_strength from battle;
mysql> select * from strength where battle_strength = (select max(battle_strength) from strength);
mysql> drop view strength;
mysql> drop view battle;
mysql> drop view battleground;
mysql> drop view noble_houses;
Session 4 - Constraints
$ mysql -u root
mysql> SET @@global.sql_mode = "STRICT_ALL_TABLES";
CTRL-D
$ mysql -u joffrey -p
mysql> use playground;
mysql> insert into persons values ('First', 'Last', 'House', 'x'); mysql> insert into persons values ('Second', 'Last', 'House', NULL);
mysql> alter table persons modify gender enum('m', 'f');
mysql> select * from persons;
mysql> update persons set gender=NULL where gender='x';
mysql> alter table persons modify gender enum('m', 'f');
mysql> delete from persons where gender is null;
mysql> alter table persons modify gender enum('m', 'f') not null;
mysql> insert into persons values ('First', 'Last', 'House', 'x');
mysql> alter table persons add constraint pk_persons primary key (first_name, last_name);
mysql> alter table persons add column id int first;
mysql> select * from persons;
mysql> alter table persons drop column id;
mysql> alter table persons add column id int primary key auto_increment first;
mysql> select * from persons;
mysql> alter table persons add unique uq_first_last (first_name, last_name);
mysql> show create table persons;
mysql> alter table locations add constraint pk_locations primary key(name);
Session 5 - Transactions
TERMINAL 0:
$ mysql -u root
mysql> use playground;
mysql> create table tx_test (name varchar(4), age integer) engine=innodb;
mysql> insert into tx_test values ('jack', 28); insert into tx_test values ('jill', 25);
mysql> select * from tx_test;
mysql> select @@global.tx_isolation;
mysql> set global transaction isolation level read uncommitted;
--- DIRTY READ ---
TERMINAL 1:
$ mysql -u joffrey -p
mysql> use playground;
mysql> start transaction;
mysql> select age from tx_test where name='jack';
TERMINAL 2:
$ mysql -u joffrey -p
mysql> use playground;
mysql> start transaction;
mysql> update tx_test set age=21 where name='jack';
TERMINAL 1:
mysql> select age from tx_test where name='jack';
TERMINAL 2:
mysql> rollback;
CTRL-D
--- NON-REPEATABLE READ ---
TERMINAL 0:
mysql> set global transaction isolation level read committed;
TERMINAL 1:
mysql> start transaction;
mysql> select * from tx_test where name='jack';
TERMINAL 2:
mysql> start transaction;
mysql> update tx_test set age=29 where name='jack';
mysql> commit;
CTRL-D
TERMINAL 1:
mysql> select * from tx_test where name='jack';
CTRL-D
--- PHANTOM READ ---
TERMINAL 0:
mysql> set global transaction isolation level repeatable read;
TERMINAL 1:
$ mysql -u joffrey -p
mysql> use playground;
mysql> start transaction;
mysql> select * from tx_test where age between 20 and 30;
TERMINAL 2:
$ mysql -u joffrey -p
mysql> use playground;
mysql> start transaction;
mysql> insert into tx_test values ('bob', 23);
mysql> commit;
CTRL-D
TERMINAL 1:
mysql> select * from tx_test where age between 20 and 30;
mysql> commit;
mysql> select * from tx_test where age between 20 and 30;
CTRL-D
--- DEADLOCK ---
TERMINAL 0:
mysql> alter table tx_test add money integer;
mysql> update tx_test set money=100;
mysql> delete from tx_test where name='bob';
mysql> set global transaction isolation level read committed;
TERMINAL 1:
$ mysql -u joffrey -p
mysql> use playground;
mysql> start transaction;
TERMINAL 2:
$ mysql -u joffrey -p
mysql> use playground;
mysql> start transaction;
TERMINAL 1:
mysql> update tx_test set money=money-50 where name='jack';
TERMINAL 2:
mysql> update tx_test set money=money-50 where name='jill';
TERMINAL 1:
mysql> update tx_test set money=money+50 where name='jill';
TERMINAL 2:
mysql> update tx_test set money=money+50 where name='jack';
TERMINAL 1:
mysql> commit;
Session 6 - SQL Injection
$ mysql -u root -p mysql> use playground mysql> create table users (id integer, login varchar(255), password varchar(255)) engine=innodb; mysql> insert into users values (0, 'root', sha(concat('salt', 'hunter2'))); mysql> select * from users where login='root' and password=sha(concat('salt','hunter2')); CTRL-D
#!/usr/bin/python import MySQLdb import MySQLdb.cursors session = MySQLdb.connect(host="localhost", user="joffrey", passwd="kings_landing", db="playground", cursorclass = MySQLdb.cursors.SSCursor) cur = session.cursor() login = raw_input('login: ') password = raw_input('password: ') print "select * from users where login=\'%s\' and password=sha(concat('salt', '%s'))" % (login, password) cur.execute("select * from users where login=\'%s\' and password=sha(concat('salt', '%s'))" % (login, password)) if cur.fetchone() is not None: print 'logged in' else: print 'wrong login or password' cur.close() session.close()
$ ./inject.py login: root password: ')) or 1=1;# $ ./inject.py login: root password: ')) or 1=1; update users set password=sha(concat('salt','mypass'));#
Session 7 - Indexes
#!/usr/bin/python import random import time import MySQLdb con = MySQLdb.connect(host="localhost", user="joffrey", passwd="kings_landing", db="playground") con.autocommit(True) cur = con.cursor() try: cur.execute('drop table large_table') except: pass cur.execute('create table large_table (l char, s varchar(255), n int) engine=innodb') ts = time.time() for i in xrange(1000000): if i%10 == 0: print i cur.execute("INSERT INTO large_table VALUES ('%s', '%s', %i)" % (chr(random.randrange(65, 91)), .join([chr(random.randrange(65, 91)) for i in xrange(1,16)]), random.randint(0,1000000))) print 'time taken:', time.time()-ts con.close()
$ mysql -u joffrey -p mysql> use playground; mysql> select l, count(*) from large_table group by l; mysql> create index idx_l on large_table(l); mysql> select s, count(*) from large_table where s like 'AB%'; mysql> create index idx_l on large_table(l); mysql> select s, count(*) from large_table where s like 'AB%';
Session 8 - Partitioning
create table large_table (l char, s varchar(255), n int) engine=innodb partition by range (n) ( partition p0 values less than (500000), partition p1 values less than maxvalue );
create table large_table (l char, s varchar(255), n int) engine=innodb partition by hash(n) partitions 10;
create table large_table (l char, s varchar(255), n int) engine=innodb partition by list(l) ( partition p0 values in ('A', ... , 'L'), partition p1 values in ('M, ... , 'Z') );
Session 9 - Execution plans
$ mysql -u joffrey -p mysql> use playground mysql> explain <any statement>
Session X - Application development
/* gcc -Wall $(mysql_config --cflags --libs) basic.c -o basic */ #include <stdio.h> #include <stdlib.h> #include <mysql.h> int main() { MYSQL *con = mysql_init(NULL); MYSQL_RES *cur; MYSQL_ROW row; int cols, i; mysql_real_connect(con, "localhost", "joffrey", "kings_landing", "playground", 0, NULL, 0); mysql_query(con, "select * from persons"); cur = mysql_store_result(con); cols = mysql_num_fields(cur); while ((row = mysql_fetch_row(cur))) { for(i = 0; i < cols; i++) { printf("%s ", row[i] ? row[i] : "<NULL>"); } printf("\n"); } mysql_free_result(cur); mysql_close(con); return 0; }
#!/usr/bin/python import MySQLdb import MySQLdb.cursors session = MySQLdb.connect(host="localhost", user="joffrey", passwd="kings_landing", db="playground", cursorclass = MySQLdb.cursors.SSCursor) cur = session.cursor() cur.execute('select * from persons') for row in cur.fetchall(): for col in row: print col if col else '<NULL>', print cur.close() session.close()
#!/usr/bin/python import MySQLdb import MySQLdb.cursors from multiprocessing import Process from random import randint from time import sleep def get_session(): return MySQLdb.connect(host='localhost', user='joffrey', passwd='kings_landing', db='playground', cursorclass=MySQLdb.cursors.SSCursor) def bootstrap_tables(): cur = get_session().cursor() try: print 'trying to create new table' cur.execute('create table mp_test (value int)') except: print 'table alread existed, truncating instead' cur.execute('truncate table mp_test') cur.close() def insert_rows(): while True: print 'inserting' session = get_session() cur = session.cursor() cur.execute('insert into mp_test values (%s)', randint(0,9)) session.commit() cur.close() session.close() sleep(0.1) def delete_rows(): while True: print 'deleting' session = get_session() cur = session.cursor() cur.execute('delete from mp_test where value = %s', randint(0,9)) session.commit() cur.close() session.close() sleep(0.1) def count_rows(): while True: session = get_session() cur = session.cursor() cur.execute('select count(*) from mp_test') res = cur.fetchone() print 'rows', res[0] cur.close() session.close() sleep(1) if __name__ == '__main__': bootstrap_tables() p_inserter = Process(target=insert_rows) p_deleter = Process(target=delete_rows) p_counter = Process(target=count_rows) p_inserter.start() p_deleter.start() p_counter.start() p_inserter.join() p_deleter.join() p_counter.join()