Difference between revisions of "Relational and non-relational databases"
From Gridkaschool
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<pre> |
<pre> |
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import sqlite3 |
import sqlite3 |
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+ | |||
import MySQLdb |
import MySQLdb |
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+ | import MySQLdb.cursors |
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+ | |||
import psycopg2 |
import psycopg2 |
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− | + | # connect to the database and set transaction level to autocommit |
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+ | s_con = sqlite3.connect(database='/tmp/student.db', isolation_level=None) # None, 'DEFERRED', 'IMMEDIATE', 'EXCLUSIVE' |
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− | m_con = MySQLdb.connect(host='localhost', user='student', passwd='student', db='student', ) |
+ | m_con = MySQLdb.connect(host='localhost', user='student', passwd='student', db='student', cursorclass = MySQLdb.cursors.SSCursor) |
+ | m_con.autocommit(True) # True, False |
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p_con = psycopg2.connect('host=localhost user=student password=student dbname=student') |
p_con = psycopg2.connect('host=localhost user=student password=student dbname=student') |
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+ | p_con.set_isolation_level(0) # 0 (AUTOCOMMIT), 1 (READ COMMIT), 3 (SERIALIZE) |
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+ | |||
+ | |||
+ | # get cursor |
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+ | s_cur = s_con.cursor() |
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+ | m_cur = m_con.cursor() |
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+ | p_cur = p_con.cursor() |
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+ | |||
+ | |||
+ | # drop old tables if they exist, ignore otherwise |
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+ | try: s_cur.execute("DROP TABLE test_table") |
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+ | except: pass |
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+ | try: m_cur.execute("DROP TABLE test_table") |
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+ | except: pass |
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+ | try: p_cur.execute("DROP TABLE test_table") |
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+ | except: pass |
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+ | |||
+ | |||
+ | # create table |
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+ | s_cur.execute("CREATE TABLE test_table (id INTEGER PRIMARY KEY, value VARCHAR(255))") |
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+ | m_cur.execute("CREATE TABLE test_table (id INTEGER PRIMARY KEY, value VARCHAR(255)) Engine=InnoDB") |
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+ | p_cur.execute("CREATE TABLE test_table (id INTEGER PRIMARY KEY, value VARCHAR(255))") |
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+ | |||
+ | |||
+ | # insert data |
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+ | s_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my first value')") |
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+ | s_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my second value')") |
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+ | s_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my second value')") |
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+ | |||
+ | m_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my first value')") |
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+ | m_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my second value')") |
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+ | m_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my second value')") |
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+ | |||
+ | p_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my first value')") |
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+ | p_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my second value')") |
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+ | p_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my second value')") |
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+ | |||
+ | |||
+ | # selecting data (everything) |
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+ | print 'sqlite' |
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+ | s_cur.execute("SELECT id, value FROM test_table") |
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+ | print s_cur.fetchall() |
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+ | |||
+ | print 'mysql' |
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+ | m_cur.execute("SELECT id, value FROM test_table") |
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+ | print m_cur.fetchall() |
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+ | |||
+ | print 'postgresql' |
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+ | p_cur.execute("SELECT id, value FROM test_table") |
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+ | print p_cur.fetchall() |
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+ | |||
+ | |||
+ | # selecting data (iteratively) |
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+ | print 'sqlite' |
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+ | s_cur.execute("SELECT id, value FROM test_table") |
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+ | for row in s_cur: |
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+ | print row |
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+ | |||
+ | print 'mysql' |
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+ | m_cur.execute("SELECT id, value FROM test_table") |
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+ | for row in m_cur: |
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+ | print row |
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+ | |||
+ | print 'postgresql' |
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+ | p_cur.execute("SELECT id, value FROM test_table") |
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+ | for row in p_cur: |
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+ | print row |
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+ | |||
+ | # close everything |
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+ | |||
+ | s_cur.close() |
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+ | m_cur.close() |
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+ | p_cur.close() |
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s_con.close() |
s_con.close() |
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m_con.close() |
m_con.close() |
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p_con.close() |
p_con.close() |
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+ | |||
</pre> |
</pre> |
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Revision as of 14:18, 27 August 2013
import sqlite3 import MySQLdb import MySQLdb.cursors import psycopg2 # connect to the database and set transaction level to autocommit s_con = sqlite3.connect(database='/tmp/student.db', isolation_level=None) # None, 'DEFERRED', 'IMMEDIATE', 'EXCLUSIVE' m_con = MySQLdb.connect(host='localhost', user='student', passwd='student', db='student', cursorclass = MySQLdb.cursors.SSCursor) m_con.autocommit(True) # True, False p_con = psycopg2.connect('host=localhost user=student password=student dbname=student') p_con.set_isolation_level(0) # 0 (AUTOCOMMIT), 1 (READ COMMIT), 3 (SERIALIZE) # get cursor s_cur = s_con.cursor() m_cur = m_con.cursor() p_cur = p_con.cursor() # drop old tables if they exist, ignore otherwise try: s_cur.execute("DROP TABLE test_table") except: pass try: m_cur.execute("DROP TABLE test_table") except: pass try: p_cur.execute("DROP TABLE test_table") except: pass # create table s_cur.execute("CREATE TABLE test_table (id INTEGER PRIMARY KEY, value VARCHAR(255))") m_cur.execute("CREATE TABLE test_table (id INTEGER PRIMARY KEY, value VARCHAR(255)) Engine=InnoDB") p_cur.execute("CREATE TABLE test_table (id INTEGER PRIMARY KEY, value VARCHAR(255))") # insert data s_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my first value')") s_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my second value')") s_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my second value')") m_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my first value')") m_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my second value')") m_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my second value')") p_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my first value')") p_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my second value')") p_cur.execute("INSERT INTO test_table(id, value) VALUES (0, 'my second value')") # selecting data (everything) print 'sqlite' s_cur.execute("SELECT id, value FROM test_table") print s_cur.fetchall() print 'mysql' m_cur.execute("SELECT id, value FROM test_table") print m_cur.fetchall() print 'postgresql' p_cur.execute("SELECT id, value FROM test_table") print p_cur.fetchall() # selecting data (iteratively) print 'sqlite' s_cur.execute("SELECT id, value FROM test_table") for row in s_cur: print row print 'mysql' m_cur.execute("SELECT id, value FROM test_table") for row in m_cur: print row print 'postgresql' p_cur.execute("SELECT id, value FROM test_table") for row in p_cur: print row # close everything s_cur.close() m_cur.close() p_cur.close() s_con.close() m_con.close() p_con.close()
import sqlite3 import MySQLdb import psycopg2 s_con = sqlite3.connect(database='/home/username/student.db') m_con = MySQLdb.connect(host='localhost', user='student', passwd='student', db='student') p_con = psycopg2.connect('host=localhost user=student password=student dbname=student') s_con.close() m_con.close() p_con.close()
CREATE TABLE test_table (id integer, name varchar(255));
Hosts:
ssh <username>@<host>.scc.kit.edu -p24
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