

In [1]:

    
import blaze

Connecting to a Database

In this tutorial we will use SQLite to make it easy to produce a self-contained, runable, tutorial.



In [2]:

    
import sqlite3 as db

Create schema:



In [3]:

    
conn = db.connect(":memory:")
c = conn.cursor()
c.execute('''create table TestTable
(id INTEGER PRIMARY KEY, content text, value real)''')









    Out[3]:





<sqlite3.Cursor at 0x1149dd9d0>

Populate Test Table:



In [4]:

    
data = [
    (1,  "hello", 2.1),
    (2,  "world", 4.2),
    (3, "!",     8.4),
]

c.executemany("""insert into testtable
              values (?, ?, ?)""", data)
conn.commit()
c.close()



In [5]:

    
list(conn.execute("SELECT * from TestTable"))









    Out[5]:





[(1, u'hello', 2.1), (2, u'world', 4.2), (3, u'!', 8.4)]

Connecting from Blaze

We can connect to an SQL database using the sql_table and sql_column functions.



In [6]:

    
from datashape import dshape
from blaze.io.sql import sql_table, sql_column



In [7]:

    
table = sql_table(
            'testtable',
            ['id', 'msg', 'price'],
            [dshape('int32'), dshape('string'), dshape('float64')],
            conn)



In [8]:

    
print table









    



<sql col testtable.* with shape var * { id : int32, msg : string, price : float64 }>



In [9]:

    
table['id']









    Out[9]:





SQLDataDescriptor(testtable.id)



In [10]:

    
blaze.eval(table['id'])









    Out[10]:





array([1, 2, 3],
      dshape='3 * int32')