Here is the first installment of SQL helper functions which I use with two classes that I wrote which encapsulate a MySQL server and a MySQL client. These helpers make it easy to convert back and forth between python dictionaries and SQL tables. -
def MySQLSelect(table, arglist=[], argdict={}, **kwargs):
-
"""Build an SQL SELECT command from the arguments:
-
Return a single string which can be 'execute'd.
-
arglist is a list of strings that are column names to get.
-
argdict and kwargs are two way to evaluate 'colName'=value
-
for the WHERE clause"""
-
a = ', '.join(arglist)
-
args = argdict.copy()
-
args.update(kwargs)
-
for key, value in args.items():
-
args[key] = (str(value), repr(value))[type(value) == str]
-
b = ''
-
if args:
-
b = 'WHERE %s' % ' AND '.join(key + '=' + value
-
for key, value in args.items())
-
return ' '.join(['SELECT', (a or '*'), 'FROM', table, b])
-
6  5809 
Here is the next installment: -
-
def MySQLInsert(table, argdict={}, **kwargs):
-
"""Build an SQL INSERT command from the arguments:
-
Return a single string which can be 'execute'd.
-
argdict is a dictionary of 'column_name':value items.
-
**kwargs is the same but passed in as column_name=value"""
-
args = argdict.copy()
-
args.update(kwargs)
-
keys = args.keys()
-
argslist = []
-
for key in keys:
-
a = args[key]
-
argslist.append((str(a), repr(a))[type(a) == str])
-
a = '(%s)' %', '.join(field for field in keys)
-
b = '(%s)' %', '.join(argslist)
-
return ' '.join(['INSERT', table, a, 'VALUES', b])
-
Here's the update converter: -
-
-
def MySQLUpdate(table, valuedict, argdict={}, **kwargs):
-
"""Build an SQL SELECT command from the arguments:
-
Return a single string which can be 'execute'd.
-
valuedict is a dictionary of column_names:value to update.
-
argdict and kwargs are two way to evaluate 'colName'=value
-
for the WHERE clause."""
-
vargs = valuedict.copy()
-
for key, value in vargs.items():
-
vargs[key] = (str(value), repr(value))[type(value) == str]
-
a = 'SET %s' % ', '.join(key + '=' + value
-
for key, value in vargs.items())
-
args = argdict.copy()
-
args.update(kwargs)
-
for key, value in args.items():
-
args[key] = (str(value), repr(value))[type(value) == str]
-
b = ''
-
if args:
-
b = 'WHERE %s' % ' AND '.join(key + '=' + value
-
for key, value in args.items())
-
-
return ' '.join(['UPDATE', table, a, b])
Here's a pretty simplistic delete fuction; -
-
-
def MySQLDelete(table, argdict={}, **kwargs):
-
"""Build an SQL DELETE command from the arguments:
-
Return a single string which can be 'execute'd.
-
argdict and kwargs are two way to evaluate 'colName':value
-
for the WHERE clause."""
-
args = argdict.copy()
-
args.update(kwargs)
-
for key, value in args.items():
-
args[key] = (str(value), repr(value))[type(value) == str]
-
b = ''
-
if args:
-
b = 'WHERE %s' % ' AND '.join(key + '=' + value
-
for key, value in args.items())
-
return ' '.join(['DELETE FROM', table, b])
-
-
And here is a class that I call a server because it stores the connection and cursor, handles errors and sends info (last query, etc) to its master's write() command. called with sys.stdout as the master, my dbServer prints to stdout. -
from MySQLdb import *
-
from time import time
-
-
class DBServer:
-
def __init__(self, master):
-
self.master = master
-
-
def Login(self, servername, username, password, database=""):
-
try:
-
self.dbconnect = connect(host=servername, user=username, passwd=password, db=database)
-
except (DatabaseError, OperationalError):
-
self.dbconnect = None
-
self.master.write('Couldn\'t connect to the database named %s on host %s'
-
%(repr(database), repr(servername)))
-
return
-
self.dbcursor = self.dbconnect.cursor()
-
self.Execute('SET autocommit=1')
-
return self.dbconnect
-
-
def DBError(self):
-
"""Remove the current message from the cursor
-
and display it."""
-
try:
-
(error, message) = self.dbcursor.messages.pop()
-
except AttributeError:
-
(error, message) = self.dbconnect.messages.pop()
-
self.master.write('%s #%d: %s' %(str(error).split('.')[-1],
-
message[0], message[1]))
-
-
def Execute(self, query):
-
try:
-
cursor = self.dbcursor
-
now = time()
-
cursor.execute(query)
-
nRows = cursor.rowcount
-
self.master.write(query)
-
self.master.write("%d rows affected: %.2f sec." %(nRows, time() - now))
-
except (DatabaseError, OperationalError):
-
self.DBError()
-
return
-
return cursor
-
-
def DBExists(self, database):
-
"""Return True if database exists"""
-
resultset = self.Execute("show databases").fetchall()
-
## print resultset
-
return (database,) in resultset
-
-
def close(self):
-
self.dbconnect.close()
-
This topic is currently being discussed, so I'm bumping this thread.
This topic is currently being discussed, so I'm bumping this thread.
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