frappe/frappe/database.py

# Copyright (c) 2015, Frappe Technologies Pvt. Ltd. and Contributors
# MIT License. See license.txt

# Database Module
# --------------------

from __future__ import unicode_literals
import MySQLdb
from MySQLdb.times import DateTimeDeltaType
from markdown2 import UnicodeWithAttrs
import warnings
import datetime
import frappe
import frappe.defaults
import frappe.async
import re
import redis
import frappe.model.meta
from frappe.utils import now, get_datetime, cstr
from frappe import _
from types import StringType, UnicodeType
from frappe.utils.global_search import sync_global_search
from frappe.model.utils.link_count import flush_local_link_count
from six import iteritems


class Database:
	"""
	   Open a database connection with the given parmeters, if use_default is True, use the
	   login details from `conf.py`. This is called by the request handler and is accessible using
	   the `db` global variable. the `sql` method is also global to run queries
	"""
	def __init__(self, host=None, user=None, password=None, ac_name=None, use_default = 0):
		self.host = host or frappe.conf.db_host or 'localhost'
		self.user = user or frappe.conf.db_name
		self._conn = None

		if ac_name:
			self.user = self.get_db_login(ac_name) or frappe.conf.db_name

		if use_default:
			self.user = frappe.conf.db_name

		self.transaction_writes = 0
		self.auto_commit_on_many_writes = 0

		self.password = password or frappe.conf.db_password
		self.value_cache = {}

	def get_db_login(self, ac_name):
		return ac_name

	def connect(self):
		"""Connects to a database as set in `site_config.json`."""
		warnings.filterwarnings('ignore', category=MySQLdb.Warning)
		self._conn = MySQLdb.connect(user=self.user, host=self.host, passwd=self.password,
			use_unicode=True, charset='utf8mb4')
		self._conn.converter[246]=float
		self._conn.converter[12]=get_datetime
		self._conn.encoders[UnicodeWithAttrs] = self._conn.encoders[UnicodeType]
		self._conn.encoders[DateTimeDeltaType] = self._conn.encoders[StringType]

		MYSQL_OPTION_MULTI_STATEMENTS_OFF = 1
		self._conn.set_server_option(MYSQL_OPTION_MULTI_STATEMENTS_OFF)

		self._cursor = self._conn.cursor()
		if self.user != 'root':
			self.use(self.user)
		frappe.local.rollback_observers = []

	def use(self, db_name):
		"""`USE` db_name."""
		self._conn.select_db(db_name)
		self.cur_db_name = db_name

	def validate_query(self, q):
		"""Throw exception for dangerous queries: `ALTER`, `DROP`, `TRUNCATE` if not `Administrator`."""
		cmd = q.strip().lower().split()[0]
		if cmd in ['alter', 'drop', 'truncate'] and frappe.session.user != 'Administrator':
			frappe.throw(_("Not permitted"), frappe.PermissionError)

	def sql(self, query, values=(), as_dict = 0, as_list = 0, formatted = 0,
		debug=0, ignore_ddl=0, as_utf8=0, auto_commit=0, update=None):
		"""Execute a SQL query and fetch all rows.

		:param query: SQL query.
		:param values: List / dict of values to be escaped and substituted in the query.
		:param as_dict: Return as a dictionary.
		:param as_list: Always return as a list.
		:param formatted: Format values like date etc.
		:param debug: Print query and `EXPLAIN` in debug log.
		:param ignore_ddl: Catch exception if table, column missing.
		:param as_utf8: Encode values as UTF 8.
		:param auto_commit: Commit after executing the query.
		:param update: Update this dict to all rows (if returned `as_dict`).

		Examples:

			# return customer names as dicts
			frappe.db.sql("select name from tabCustomer", as_dict=True)

			# return names beginning with a
			frappe.db.sql("select name from tabCustomer where name like %s", "a%")

			# values as dict
			frappe.db.sql("select name from tabCustomer where name like %(name)s and owner=%(owner)s",
				{"name": "a%", "owner":"test@example.com"})

		"""
		if not self._conn:
			self.connect()

		# in transaction validations
		self.check_transaction_status(query)

		# autocommit
		if auto_commit: self.commit()

		# execute
		try:
			if values!=():
				if isinstance(values, dict):
					values = dict(values)

				# MySQL-python==1.2.5 hack!
				if not isinstance(values, (dict, tuple, list)):
					values = (values,)

				if debug:
					try:
						self.explain_query(query, values)
						frappe.errprint(query % values)
					except TypeError:
						frappe.errprint([query, values])

				if (frappe.conf.get("logging") or False)==2:
					frappe.log("<<<< query")
					frappe.log(query)
					frappe.log("with values:")
					frappe.log(values)
					frappe.log(">>>>")
				self._cursor.execute(query, values)

			else:
				if debug:
					self.explain_query(query)
					frappe.errprint(query)
				if (frappe.conf.get("logging") or False)==2:
					frappe.log("<<<< query")
					frappe.log(query)
					frappe.log(">>>>")

				self._cursor.execute(query)

		except Exception as e:
			# ignore data definition errors
			if ignore_ddl and e.args[0] in (1146,1054,1091):
				pass

			# NOTE: causes deadlock
			# elif e.args[0]==2006:
			# 	# mysql has gone away
			# 	self.connect()
			# 	return self.sql(query=query, values=values,
			# 		as_dict=as_dict, as_list=as_list, formatted=formatted,
			# 		debug=debug, ignore_ddl=ignore_ddl, as_utf8=as_utf8,
			# 		auto_commit=auto_commit, update=update)

			else:
				raise

		if auto_commit: self.commit()

		# scrub output if required
		if as_dict:
			ret = self.fetch_as_dict(formatted, as_utf8)
			if update:
				for r in ret:
					r.update(update)
			return ret
		elif as_list:
			return self.convert_to_lists(self._cursor.fetchall(), formatted, as_utf8)
		elif as_utf8:
			return self.convert_to_lists(self._cursor.fetchall(), formatted, as_utf8)
		else:
			return self._cursor.fetchall()

	def explain_query(self, query, values=None):
		"""Print `EXPLAIN` in error log."""
		try:
			frappe.errprint("--- query explain ---")
			if values is None:
				self._cursor.execute("explain " + query)
			else:
				self._cursor.execute("explain " + query, values)
			import json
			frappe.errprint(json.dumps(self.fetch_as_dict(), indent=1))
			frappe.errprint("--- query explain end ---")
		except:
			frappe.errprint("error in query explain")

	def sql_list(self, query, values=(), debug=False):
		"""Return data as list of single elements (first column).

		Example:

			# doctypes = ["DocType", "DocField", "User", ...]
			doctypes = frappe.db.sql_list("select name from DocType")
		"""
		return [r[0] for r in self.sql(query, values, debug=debug)]

	def sql_ddl(self, query, values=(), debug=False):
		"""Commit and execute a query. DDL (Data Definition Language) queries that alter schema
		autocommit in MariaDB."""
		self.commit()
		self.sql(query, debug=debug)

	def check_transaction_status(self, query):
		"""Raises exception if more than 20,000 `INSERT`, `UPDATE` queries are
		executed in one transaction. This is to ensure that writes are always flushed otherwise this
		could cause the system to hang."""
		if self.transaction_writes and \
			query and query.strip().split()[0].lower() in ['start', 'alter', 'drop', 'create', "begin", "truncate"]:
			raise Exception('This statement can cause implicit commit')

		if query and query.strip().lower() in ('commit', 'rollback'):
			self.transaction_writes = 0

		if query[:6].lower() in ('update', 'insert', 'delete'):
			self.transaction_writes += 1
			if self.transaction_writes > 200000:
				if self.auto_commit_on_many_writes:
					frappe.db.commit()
				else:
					frappe.throw(_("Too many writes in one request. Please send smaller requests"), frappe.ValidationError)

	def fetch_as_dict(self, formatted=0, as_utf8=0):
		"""Internal. Converts results to dict."""
		result = self._cursor.fetchall()
		ret = []
		needs_formatting = self.needs_formatting(result, formatted)

		for r in result:
			row_dict = frappe._dict({})
			for i in range(len(r)):
				if needs_formatting:
					val = self.convert_to_simple_type(r[i], formatted)
				else:
					val = r[i]

				if as_utf8 and type(val) is unicode:
					val = val.encode('utf-8')
				row_dict[self._cursor.description[i][0]] = val
			ret.append(row_dict)
		return ret

	def needs_formatting(self, result, formatted):
		"""Returns true if the first row in the result has a Date, Datetime, Long Int."""
		if result and result[0]:
			for v in result[0]:
				if isinstance(v, (datetime.date, datetime.timedelta, datetime.datetime, long)):
					return True
				if formatted and isinstance(v, (int, float)):
					return True

		return False

	def get_description(self):
		"""Returns result metadata."""
		return self._cursor.description

	def convert_to_simple_type(self, v, formatted=0):
		"""Format date, time, longint values."""
		return v

		from frappe.utils import formatdate, fmt_money

		if isinstance(v, (datetime.date, datetime.timedelta, datetime.datetime, long)):
			if isinstance(v, datetime.date):
				v = unicode(v)
				if formatted:
					v = formatdate(v)

			# time
			elif isinstance(v, (datetime.timedelta, datetime.datetime)):
				v = unicode(v)

			# long
			elif isinstance(v, long):
				v=int(v)

		# convert to strings... (if formatted)
		if formatted:
			if isinstance(v, float):
				v=fmt_money(v)
			elif isinstance(v, int):
				v = unicode(v)

		return v

	def convert_to_lists(self, res, formatted=0, as_utf8=0):
		"""Convert tuple output to lists (internal)."""
		nres = []
		needs_formatting = self.needs_formatting(res, formatted)
		for r in res:
			nr = []
			for c in r:
				if needs_formatting:
					val = self.convert_to_simple_type(c, formatted)
				else:
					val = c
				if as_utf8 and type(val) is unicode:
					val = val.encode('utf-8')
				nr.append(val)
			nres.append(nr)
		return nres

	def convert_to_utf8(self, res, formatted=0):
		"""Encode result as UTF-8."""
		nres = []
		for r in res:
			nr = []
			for c in r:
				if type(c) is unicode:
					c = c.encode('utf-8')
					nr.append(self.convert_to_simple_type(c, formatted))
			nres.append(nr)
		return nres

	def build_conditions(self, filters):
		"""Convert filters sent as dict, lists to SQL conditions. filter's key
		is passed by map function, build conditions like:

		* ifnull(`fieldname`, default_value) = %(fieldname)s
		* `fieldname` [=, !=, >, >=, <, <=] %(fieldname)s
		"""
		conditions = []
		values = {}
		def _build_condition(key):
			"""
				filter's key is passed by map function
				build conditions like:
					* ifnull(`fieldname`, default_value) = %(fieldname)s
					* `fieldname` [=, !=, >, >=, <, <=] %(fieldname)s
			"""
			_operator = "="
			_rhs = " %(" + key + ")s"
			value = filters.get(key)
			values[key] = value
			if isinstance(value, (list, tuple)):
				# value is a tuble like ("!=", 0)
				_operator = value[0]
				values[key] = value[1]
				if isinstance(value[1], (tuple, list)):
					# value is a list in tuple ("in", ("A", "B"))
					inner_list = []
					for i, v in enumerate(value[1]):
						inner_key = "{0}_{1}".format(key, i)
						values[inner_key] = v
						inner_list.append("%({0})s".format(inner_key))

					_rhs = " ({0})".format(", ".join(inner_list))
					del values[key]

			if _operator not in ["=", "!=", ">", ">=", "<", "<=", "like", "in", "not in", "not like"]:
				_operator = "="

			if "[" in key:
				split_key = key.split("[")
				condition = "ifnull(`" + split_key[0] + "`, " + split_key[1][:-1] + ") " \
					+ _operator + _rhs
			else:
				condition = "`" + key + "` " + _operator + _rhs

			conditions.append(condition)

		if isinstance(filters, basestring):
			filters = { "name": filters }

		for f in filters:
			_build_condition(f)

		return " and ".join(conditions), values

	def get(self, doctype, filters=None, as_dict=True, cache=False):
		"""Returns `get_value` with fieldname='*'"""
		return self.get_value(doctype, filters, "*", as_dict=as_dict, cache=cache)

	def get_value(self, doctype, filters=None, fieldname="name", ignore=None, as_dict=False,
		debug=False, order_by=None, cache=False):
		"""Returns a document property or list of properties.

		:param doctype: DocType name.
		:param filters: Filters like `{"x":"y"}` or name of the document. `None` if Single DocType.
		:param fieldname: Column name.
		:param ignore: Don't raise exception if table, column is missing.
		:param as_dict: Return values as dict.
		:param debug: Print query in error log.
		:param order_by: Column to order by

		Example:

			# return first customer starting with a
			frappe.db.get_value("Customer", {"name": ("like a%")})

			# return last login of **User** `test@example.com`
			frappe.db.get_value("User", "test@example.com", "last_login")

			last_login, last_ip = frappe.db.get_value("User", "test@example.com",
				["last_login", "last_ip"])

			# returns default date_format
			frappe.db.get_value("System Settings", None, "date_format")
		"""

		ret = self.get_values(doctype, filters, fieldname, ignore, as_dict, debug,
			order_by, cache=cache)

		return ((len(ret[0]) > 1 or as_dict) and ret[0] or ret[0][0]) if ret else None

	def get_values(self, doctype, filters=None, fieldname="name", ignore=None, as_dict=False,
		debug=False, order_by=None, update=None, cache=False):
		"""Returns multiple document properties.

		:param doctype: DocType name.
		:param filters: Filters like `{"x":"y"}` or name of the document.
		:param fieldname: Column name.
		:param ignore: Don't raise exception if table, column is missing.
		:param as_dict: Return values as dict.
		:param debug: Print query in error log.
		:param order_by: Column to order by

		Example:

			# return first customer starting with a
			customers = frappe.db.get_values("Customer", {"name": ("like a%")})

			# return last login of **User** `test@example.com`
			user = frappe.db.get_values("User", "test@example.com", "*")[0]
		"""
		out = None
		if cache and isinstance(filters, basestring) and \
			(doctype, filters, fieldname) in self.value_cache:
			return self.value_cache[(doctype, filters, fieldname)]

		if not order_by: order_by = 'modified desc'

		if isinstance(filters, list):
			out = self._get_value_for_many_names(doctype, filters, fieldname, debug=debug)

		else:
			fields = fieldname
			if fieldname!="*":
				if isinstance(fieldname, basestring):
					fields = [fieldname]
				else:
					fields = fieldname

			if (filters is not None) and (filters!=doctype or doctype=="DocType"):
				try:
					out = self._get_values_from_table(fields, filters, doctype, as_dict, debug, order_by, update)
				except Exception as e:
					if ignore and e.args[0] in (1146, 1054):
						# table or column not found, return None
						out = None
					elif (not ignore) and e.args[0]==1146:
						# table not found, look in singles
						out = self.get_values_from_single(fields, filters, doctype, as_dict, debug, update)
					else:
						raise
			else:
				out = self.get_values_from_single(fields, filters, doctype, as_dict, debug, update)

		if cache and isinstance(filters, basestring):
			self.value_cache[(doctype, filters, fieldname)] = out

		return out

	def get_values_from_single(self, fields, filters, doctype, as_dict=False, debug=False, update=None):
		"""Get values from `tabSingles` (Single DocTypes) (internal).

		:param fields: List of fields,
		:param filters: Filters (dict).
		:param doctype: DocType name.
		"""
		# TODO
		# if not frappe.model.meta.is_single(doctype):
		# 	raise frappe.DoesNotExistError("DocType", doctype)

		if fields=="*" or isinstance(filters, dict):
			# check if single doc matches with filters
			values = self.get_singles_dict(doctype)
			if isinstance(filters, dict):
				for key, value in filters.items():
					if values.get(key) != value:
						return []

			if as_dict:
				return values and [values] or []

			if isinstance(fields, list):
				return [map(lambda d: values.get(d), fields)]

		else:
			r = self.sql("""select field, value
				from tabSingles where field in (%s) and doctype=%s""" \
					% (', '.join(['%s'] * len(fields)), '%s'),
					tuple(fields) + (doctype,), as_dict=False, debug=debug)

			if as_dict:
				if r:
					r = frappe._dict(r)
					if update:
						r.update(update)
					return [r]
				else:
					return []
			else:
				return r and [[i[1] for i in r]] or []

	def get_singles_dict(self, doctype):
		"""Get Single DocType as dict.

		:param doctype: DocType of the single object whose value is requested

		Example:

			# Get coulmn and value of the single doctype Accounts Settings
			account_settings = frappe.db.get_singles_dict("Accounts Settings")
		"""

		return frappe._dict(self.sql("""select field, value from
			tabSingles where doctype=%s""", doctype))

	def get_all(self, *args, **kwargs):
		return frappe.get_all(*args, **kwargs)

	def get_list(self, *args, **kwargs):
		return frappe.get_list(*args, **kwargs)

	def get_single_value(self, doctype, fieldname, cache=False):
		"""Get property of Single DocType. Cache locally by default

		:param doctype: DocType of the single object whose value is requested
		:param fieldname: `fieldname` of the property whose value is requested

		Example:

			# Get the default value of the company from the Global Defaults doctype.
			company = frappe.db.get_single_value('Global Defaults', 'default_company')
		"""

		value = self.value_cache.setdefault(doctype, {}).get(fieldname)
		if value:
			return value

		val = self.sql("""select value from
			tabSingles where doctype=%s and field=%s""", (doctype, fieldname))
		val = val[0][0] if val else None

		if val=="0" or val=="1":
			# check type
			val = int(val)

		self.value_cache[doctype][fieldname] = val

		return val

	def get_singles_value(self, *args, **kwargs):
		"""Alias for get_single_value"""
		return self.get_single_value(*args, **kwargs)

	def _get_values_from_table(self, fields, filters, doctype, as_dict, debug, order_by=None, update=None):
		fl = []
		if isinstance(fields, (list, tuple)):
			for f in fields:
				if "(" in f or " as " in f: # function
					fl.append(f)
				else:
					fl.append("`" + f + "`")
			fl = ", ".join(fl)
		else:
			fl = fields
			if fields=="*":
				as_dict = True

		conditions, values = self.build_conditions(filters)

		order_by = ("order by " + order_by) if order_by else ""

		r = self.sql("select {0} from `tab{1}` where {2} {3}".format(fl, doctype,
			conditions, order_by), values, as_dict=as_dict, debug=debug, update=update)

		return r

	def _get_value_for_many_names(self, doctype, names, field, debug=False):
		names = filter(None, names)

		if names:
			return dict(self.sql("select name, `%s` from `tab%s` where name in (%s)" \
				% (field, doctype, ", ".join(["%s"]*len(names))), names, debug=debug))
		else:
			return {}

	def update(self, *args, **kwargs):
		"""Update multiple values. Alias for `set_value`."""
		return self.set_value(*args, **kwargs)

	def set_value(self, dt, dn, field, val, modified=None, modified_by=None,
		update_modified=True, debug=False):
		"""Set a single value in the database, do not call the ORM triggers
		but update the modified timestamp (unless specified not to).

		**Warning:** this function will not call Document events and should be avoided in normal cases.

		:param dt: DocType name.
		:param dn: Document name.
		:param field: Property / field name or dictionary of values to be updated
		:param value: Value to be updated.
		:param modified: Use this as the `modified` timestamp.
		:param modified_by: Set this user as `modified_by`.
		:param update_modified: default True. Set as false, if you don't want to update the timestamp.
		:param debug: Print the query in the developer / js console.
		"""
		if not modified:
			modified = now()
		if not modified_by:
			modified_by = frappe.session.user

		to_update = {}
		if update_modified:
			to_update = {"modified": modified, "modified_by": modified_by}

		if isinstance(field, dict):
			to_update.update(field)
		else:
			to_update.update({field: val})

		if dn and dt!=dn:
			# with table
			conditions, values = self.build_conditions(dn)

			values.update(to_update)

			set_values = []
			for key in to_update:
				set_values.append('`{0}`=%({0})s'.format(key))

			self.sql("""update `tab{0}`
				set {1} where {2}""".format(dt, ', '.join(set_values), conditions),
				values, debug=debug)

		else:
			# for singles
			keys = to_update.keys()
			self.sql('''
				delete from tabSingles
				where field in ({0}) and
					doctype=%s'''.format(', '.join(['%s']*len(keys))),
					keys + [dt], debug=debug)
			for key, value in iteritems(to_update):
				self.sql('''insert into tabSingles(doctype, field, value) values (%s, %s, %s)''',
					(dt, key, value), debug=debug)

		if dt in self.value_cache:
			del self.value_cache[dt]

	def set(self, doc, field, val):
		"""Set value in document. **Avoid**"""
		doc.db_set(field, val)

	def touch(self, doctype, docname):
		"""Update the modified timestamp of this document."""
		from frappe.utils import now
		modified = now()
		frappe.db.sql("""update `tab{doctype}` set `modified`=%s
			where name=%s""".format(doctype=doctype), (modified, docname))
		return modified

	def set_temp(self, value):
		"""Set a temperory value and return a key."""
		key = frappe.generate_hash()
		frappe.cache().hset("temp", key, value)
		return key

	def get_temp(self, key):
		"""Return the temperory value and delete it."""
		return frappe.cache().hget("temp", key)

	def set_global(self, key, val, user='__global'):
		"""Save a global key value. Global values will be automatically set if they match fieldname."""
		self.set_default(key, val, user)

	def get_global(self, key, user='__global'):
		"""Returns a global key value."""
		return self.get_default(key, user)

	def set_default(self, key, val, parent="__default", parenttype=None):
		"""Sets a global / user default value."""
		frappe.defaults.set_default(key, val, parent, parenttype)

	def add_default(self, key, val, parent="__default", parenttype=None):
		"""Append a default value for a key, there can be multiple default values for a particular key."""
		frappe.defaults.add_default(key, val, parent, parenttype)

	def get_default(self, key, parent="__default"):
		"""Returns default value as a list if multiple or single"""
		d = self.get_defaults(key, parent)
		return isinstance(d, list) and d[0] or d

	def get_defaults(self, key=None, parent="__default"):
		"""Get all defaults"""
		if key:
			defaults = frappe.defaults.get_defaults(parent)
			d = defaults.get(key, None)
			if(not d and key != frappe.scrub(key)):
				d = defaults.get(frappe.scrub(key), None)
			return d
		else:
			return frappe.defaults.get_defaults(parent)

	def begin(self):
		self.sql("start transaction")

	def commit(self):
		"""Commit current transaction. Calls SQL `COMMIT`."""
		self.sql("commit")
		frappe.local.rollback_observers = []
		self.flush_realtime_log()
		self.enqueue_global_search()
		flush_local_link_count()

	def enqueue_global_search(self):
		if frappe.flags.update_global_search:
			try:
				frappe.enqueue('frappe.utils.global_search.sync_global_search',
					now=frappe.flags.in_test or frappe.flags.in_install or frappe.flags.in_migrate,
					flags=frappe.flags.update_global_search)
			except redis.exceptions.ConnectionError:
				sync_global_search()

			frappe.flags.update_global_search = []

	def flush_realtime_log(self):
		for args in frappe.local.realtime_log:
			frappe.async.emit_via_redis(*args)

		frappe.local.realtime_log = []

	def rollback(self):
		"""`ROLLBACK` current transaction."""
		self.sql("rollback")
		self.begin()
		for obj in frappe.local.rollback_observers:
			if hasattr(obj, "on_rollback"):
				obj.on_rollback()
		frappe.local.rollback_observers = []

	def field_exists(self, dt, fn):
		"""Return true of field exists."""
		return self.sql("select name from tabDocField where fieldname=%s and parent=%s", (dt, fn))

	def table_exists(self, tablename):
		"""Returns True if table exists."""
		return ("tab" + tablename) in self.get_tables()

	def get_tables(self):
		return [d[0] for d in self.sql("show tables")]

	def a_row_exists(self, doctype):
		"""Returns True if atleast one row exists."""
		return self.sql("select name from `tab{doctype}` limit 1".format(doctype=doctype))

	def exists(self, dt, dn=None):
		"""Returns true if document exists.

		:param dt: DocType name.
		:param dn: Document name or filter dict."""
		if isinstance(dt, basestring):
			if dt!="DocType" and dt==dn:
				return True # single always exists (!)
			try:
				return self.get_value(dt, dn, "name")
			except:
				return None
		elif isinstance(dt, dict) and dt.get('doctype'):
			try:
				conditions = []
				for d in dt:
					if d == 'doctype': continue
					conditions.append('`%s` = "%s"' % (d, cstr(dt[d]).replace('"', '\"')))
				return self.sql('select name from `tab%s` where %s' % \
						(dt['doctype'], " and ".join(conditions)))
			except:
				return None

	def count(self, dt, filters=None, debug=False):
		"""Returns `COUNT(*)` for given DocType and filters."""
		if filters:
			conditions, filters = self.build_conditions(filters)
			return frappe.db.sql("""select count(*)
				from `tab%s` where %s""" % (dt, conditions), filters, debug=debug)[0][0]
		else:
			return frappe.db.sql("""select count(*)
				from `tab%s`""" % (dt,))[0][0]


	def get_creation_count(self, doctype, minutes):
		"""Get count of records created in the last x minutes"""
		from frappe.utils import now_datetime
		from dateutil.relativedelta import relativedelta

		return frappe.db.sql("""select count(name) from `tab{doctype}`
			where creation >= %s""".format(doctype=doctype),
			now_datetime() - relativedelta(minutes=minutes))[0][0]

	def get_db_table_columns(self, table):
		"""Returns list of column names from given table."""
		return [r[0] for r in self.sql("DESC `%s`" % table)]

	def get_table_columns(self, doctype):
		"""Returns list of column names from given doctype."""
		return self.get_db_table_columns('tab' + doctype)

	def has_column(self, doctype, column):
		"""Returns True if column exists in database."""
		return column in self.get_table_columns(doctype)

	def add_index(self, doctype, fields, index_name=None):
		"""Creates an index with given fields if not already created.
		Index name will be `fieldname1_fieldname2_index`"""
		if not index_name:
			index_name = "_".join(fields) + "_index"

			# remove index length if present e.g. (10) from index name
			index_name = re.sub(r"\s*\([^)]+\)\s*", r"", index_name)

		if not frappe.db.sql("""show index from `tab%s` where Key_name="%s" """ % (doctype, index_name)):
			frappe.db.commit()
			frappe.db.sql("""alter table `tab%s`
				add index `%s`(%s)""" % (doctype, index_name, ", ".join(fields)))

	def add_unique(self, doctype, fields, constraint_name=None):
		if isinstance(fields, basestring):
			fields = [fields]
		if not constraint_name:
			constraint_name = "unique_" + "_".join(fields)

		if not frappe.db.sql("""select CONSTRAINT_NAME from information_schema.TABLE_CONSTRAINTS
			where table_name=%s and constraint_type='UNIQUE' and CONSTRAINT_NAME=%s""",
			('tab' + doctype, constraint_name)):
				frappe.db.commit()
				frappe.db.sql("""alter table `tab%s`
					add unique `%s`(%s)""" % (doctype, constraint_name, ", ".join(fields)))

	def get_system_setting(self, key):
		def _load_system_settings():
			return self.get_singles_dict("System Settings")
		return frappe.cache().get_value("system_settings", _load_system_settings).get(key)

	def close(self):
		"""Close database connection."""
		if self._conn:
			self._cursor.close()
			self._conn.close()
			self._cursor = None
			self._conn = None

	def escape(self, s, percent=True):
		"""Excape quotes and percent in given string."""
		if isinstance(s, unicode):
			s = (s or "").encode("utf-8")

		s = unicode(MySQLdb.escape_string(s), "utf-8").replace("`", "\\`")

		# NOTE separating % escape, because % escape should only be done when using LIKE operator
		# or when you use python format string to generate query that already has a %s
		# for example: sql("select name from `tabUser` where name=%s and {0}".format(conditions), something)
		# defaulting it to True, as this is the most frequent use case
		# ideally we shouldn't have to use ESCAPE and strive to pass values via the values argument of sql
		if percent:
			s = s.replace("%", "%%")

		return s