refactor: use `get_value` instead of `exists`
diff --git a/erpnext/accounts/doctype/pos_invoice/pos_invoice.py b/erpnext/accounts/doctype/pos_invoice/pos_invoice.py
index 2b88fe7..d782cc2 100644
--- a/erpnext/accounts/doctype/pos_invoice/pos_invoice.py
+++ b/erpnext/accounts/doctype/pos_invoice/pos_invoice.py
@@ -485,14 +485,13 @@
 			"payment_account": pay.account,
 		}, ["name"])
 
-		args = {
-			'doctype': 'Payment Request',
+		filters = {
 			'reference_doctype': 'POS Invoice',
 			'reference_name': self.name,
 			'payment_gateway_account': payment_gateway_account,
 			'email_to': self.contact_mobile
 		}
-		pr = frappe.db.exists(args)
+		pr = frappe.db.get_value('Payment Request', filters=filters)
 		if pr:
 			return frappe.get_doc('Payment Request', pr)
 
diff --git a/erpnext/crm/doctype/appointment/appointment.py b/erpnext/crm/doctype/appointment/appointment.py
index c36faaf..88a9c10 100644
--- a/erpnext/crm/doctype/appointment/appointment.py
+++ b/erpnext/crm/doctype/appointment/appointment.py
@@ -225,9 +225,7 @@
 
 
 def _get_employee_from_user(user):
-	employee_docname = frappe.db.exists(
-		{'doctype': 'Employee', 'user_id': user})
+	employee_docname = frappe.db.get_value('Employee', {'user_id': user})
 	if employee_docname:
-		# frappe.db.exists returns a tuple of a tuple
 		return frappe.get_doc('Employee', employee_docname)
 	return None
diff --git a/erpnext/crm/doctype/appointment/test_appointment.py b/erpnext/crm/doctype/appointment/test_appointment.py
index 7183737..776e604 100644
--- a/erpnext/crm/doctype/appointment/test_appointment.py
+++ b/erpnext/crm/doctype/appointment/test_appointment.py
@@ -8,7 +8,7 @@
 
 
 def create_test_lead():
-	test_lead = frappe.db.exists({"doctype": "Lead", "email_id": "test@example.com"})
+	test_lead = frappe.db.get_value("Lead", {"email_id": "test@example.com"})
 	if test_lead:
 		return frappe.get_doc("Lead", test_lead)
 	test_lead = frappe.get_doc(
@@ -19,15 +19,6 @@
 
 
 def create_test_appointments():
-	test_appointment = frappe.db.exists(
-		{
-			"doctype": "Appointment",
-			"scheduled_time": datetime.datetime.now(),
-			"email": "test@example.com",
-		}
-	)
-	if test_appointment:
-		return frappe.get_doc("Appointment", test_appointment)
 	test_appointment = frappe.get_doc(
 		{
 			"doctype": "Appointment",
diff --git a/erpnext/hr/doctype/leave_application/test_leave_application.py b/erpnext/hr/doctype/leave_application/test_leave_application.py
index e01bdf6..db4cbb7 100644
--- a/erpnext/hr/doctype/leave_application/test_leave_application.py
+++ b/erpnext/hr/doctype/leave_application/test_leave_application.py
@@ -931,10 +931,7 @@
 	dept_doc.save(ignore_permissions=True)
 
 def get_leave_period():
-	leave_period_name = frappe.db.exists({
-		"doctype": "Leave Period",
-		"company": "_Test Company"
-	})
+	leave_period_name = frappe.db.get_value("Leave Period", {"company": "_Test Company"})
 	if leave_period_name:
 		return frappe.get_doc("Leave Period", leave_period_name)
 	else: