_mssql_examples.rst

_mssql examples

Example scripts using _mssql module.

Quickstart usage of various features

from pymssql import _mssql
conn = _mssql.connect(server='SQL01', user='user', password='password', \
    database='mydatabase')
conn.execute_non_query('CREATE TABLE persons(id INT, name VARCHAR(100))')
conn.execute_non_query("INSERT INTO persons VALUES(1, 'John Doe')")
conn.execute_non_query("INSERT INTO persons VALUES(2, 'Jane Doe')")

# how to fetch rows from a table
conn.execute_query('SELECT * FROM persons WHERE salesrep=%s', 'John Doe')
for row in conn:
    print "ID=%d, Name=%s" % (row['id'], row['name'])

.. versionadded:: 2.1.0
    Iterating over query results by iterating over the connection object
    just like it's already possible with ``pymssql`` connections is new in 2.1.0.

# examples of other query functions
numemployees = conn.execute_scalar("SELECT COUNT(*) FROM employees")
numemployees = conn.execute_scalar("SELECT COUNT(*) FROM employees WHERE name LIKE 'J%'")    # note that '%' is not a special character here
employeedata = conn.execute_row("SELECT * FROM employees WHERE id=%d", 13)

# how to fetch rows from a stored procedure
conn.execute_query('sp_spaceused')   # sp_spaceused without arguments returns 2 result sets
res1 = [ row for row in conn ]       # 1st result
res2 = [ row for row in conn ]       # 2nd result

# how to get an output parameter from a stored procedure
sqlcmd = """
DECLARE @res INT
EXEC usp_mystoredproc @res OUT
SELECT @res
"""
res = conn.execute_scalar(sqlcmd)

# how to get more output parameters from a stored procedure
sqlcmd = """
DECLARE @res1 INT, @res2 TEXT, @res3 DATETIME
EXEC usp_getEmpData %d, %s, @res1 OUT, @res2 OUT, @res3 OUT
SELECT @res1, @res2, @res3
"""
res = conn.execute_row(sqlcmd, (13, 'John Doe'))

# examples of queries with parameters
conn.execute_query('SELECT * FROM empl WHERE id=%d', 13)
conn.execute_query('SELECT * FROM empl WHERE name=%s', 'John Doe')
conn.execute_query('SELECT * FROM empl WHERE id IN %s', ((5, 6),))
conn.execute_query('SELECT * FROM empl WHERE name LIKE %s', 'J%')
conn.execute_query('SELECT * FROM empl WHERE name=%(name)s AND city=%(city)s', \
    { 'name': 'John Doe', 'city': 'Nowhere' } )
conn.execute_query('SELECT * FROM cust WHERE salesrep=%s AND id IN %s', \
    ('John Doe', (1, 2, 3)))
conn.execute_query('SELECT * FROM empl WHERE id IN %s', (tuple(xrange(4)),))
conn.execute_query('SELECT * FROM empl WHERE id IN %s', \
    (tuple([3, 5, 7, 11]),))

conn.close()

Please note the usage of iterators and ability to access results by column name. Also please note that parameters to connect method have different names than in pymssql module.

An example of exception handling

from pymssql import _mssql

conn = _mssql.connect(server='SQL01', user='user', password='password',
                      database='mydatabase')
try:
    conn.execute_non_query('CREATE TABLE t1(id INT, name VARCHAR(50))')
except _mssql.MssqlDatabaseException as e:
    if e.number == 2714 and e.severity == 16:
        # table already existed, so quieten the error
    else:
        raise # re-raise real error
finally:
    conn.close()

Custom message handlers

.. versionadded:: 2.1.1

You can provide your own message handler callback function that will be invoked by the stack with informative messages sent by the server. Set it on a per _mssql :class:`connection <_mssql.MSSQLConnection>` basis by using the :meth:`_mssql.MSSQLConnection.set_msghandler` method:

from pymssql import _mssql

def my_msg_handler(msgstate, severity, srvname, procname, line, msgtext):
    """
    Our custom handler -- It simply prints a string to stdout assembled from
    the pieces of information sent by the server.
    """
    print("my_msg_handler: msgstate = %d, severity = %d, procname = '%s', "
          "line = %d, msgtext = '%s'" % (msgstate, severity, procname,
                                         line, msgtext))

cnx = _mssql.connect(server='SQL01', user='user', password='password')
try:
    cnx.set_msghandler(my_msg_handler)  # Install our custom handler
    cnx.execute_non_query("USE mydatabase")  # It gets called at this point
finally:
    cnx.close()

Something similar to this would be printed to the standard output:

my_msg_handler: msgstate = x, severity = y, procname = '', line = 1, msgtext = 'Changed database context to 'mydatabase'.'

.. todo:: Add an example of invoking a Stored Procedure using ``_mssql``.