Is calling updateItem necessary after calling setPropertyValue on item?

In this article, below scenarios are considered to see how values are updated in database and at what point.
Case 1 : What happens if setPropertyValue is called on an item - without calling updateItem and without any parent transaction?
Case 2 : What happens if setPropertyValue is called on an item - calling updateItem and without any parent transaction?
Case 3 : What happens if setPropertyValue is called on item - with parent transaction and without updateItem call?
Case 4 : What happens if setPropertyValue is called on item - With Transaction, with UpdateItem call?

=============================================================================================
Case 1 : What happens if setPropertyValue is called on an item - without calling updateItem and without any parent transaction?
for every item.setPropertyValue - update sql query is fired, commit is called, value is updated in database.

For example -

MutableRepositoryItem mutItem = repo.getItemForUpdate("900001", "addressValidation_req_log");
mutItem.setPropertyValue("city", "Des Plaines2");

In logs -
 UPDATE www_addr_verify_req_log
    SET CITY=?
  WHERE REQUEST_LOG_ID=?
-- Parameters --
p[1] = {pd: city} Des Plaines2 (java.lang.String)
p[2] = {pd} 900001 (java.lang.String)

updateItem(addressValidation_req_log:900001) (changes applied: {city=Des Plaines2})
=============================================================================================
Case 2 : What happens if setPropertyValue is called on an item - calling updateItem and without any parent transaction?
Even though updateItem is called it does'nt mean that changes in database will get updated only after updateItem is called.
In this case too, for every item.setPropertyValue - update sql query is fired, commit is called, value is updated in database.
Note: When updateItem is called seperately - Since no changes nothing is done.

For example -

mutItem.setPropertyValue("city", "Des Plaines2");
mutItem.setPropertyValue("streetAddr2", "Des 2");
repo.updateItem(mutItem);

MutableRepositoryItem mutItem = repo.getItemForUpdate("900001", "addressValidation_req_log");
mutItem.setPropertyValue("city", "Des Plaines2");

In logs -
 UPDATE www_addr_verify_req_log
    SET CITY=?
  WHERE REQUEST_LOG_ID=?
-- Parameters --
p[1] = {pd: city} Des Plaines2 (java.lang.String)
p[2] = {pd} 900001 (java.lang.String)

updateItem(addressValidation_req_log:900001) (changes applied: {city=Des Plaines2})

 UPDATE www_addr_verify_req_log
    SET STREET_ADDR2=?
  WHERE REQUEST_LOG_ID=?
-- Parameters --
p[1] = {pd: streetAddr2} Des 2 (java.lang.String)
p[2] = {pd} 900001 (java.lang.String)

updateItem(addressValidation_req_log:900001) (changes applied: {streetAddr2=Des 2})

updateItem(addressValidation_req_log:900001) (no changes)
=============================================================================================
Case 3 : What happens if setPropertyValue is called on item - with parent transaction and without updateItem call?
If transaction is in place, then only one update query is fired for all property changes for that item.
A single update query is fired at for EACH item (even if there are many properties changed) at the end of transaction.

For example:

MutableRepositoryItem mutItem = repo.getItemForUpdate("900001", "addressValidation_req_log");
mutItem.setPropertyValue("city", "Des Plaines2");
mutItem.setPropertyValue("streetAddr2", "Des 2");

setPropertyValue(addressValidation_req_log:900001.city,Des Plaines2)
setPropertyValue(addressValidation_req_log:900001.streetAddr2,Des 2)

MutableRepositoryItem mutItem1 = repo1.getItemForUpdate("1335", "categorytier3info");
mutItem1.setPropertyValue("createUser", "mktg-team1");
mutItem1.setPropertyValue("updateUser", "mktg-team1");

setPropertyValue(categorytier3info:1335.createUser,mktg-team1)
setPropertyValue(categorytier3info:1335.updateUser,mktg-team1)

td.end(true);

In logs -
 UPDATE www_addr_verify_req_log
    SET STREET_ADDR2=?,CITY=?
  WHERE REQUEST_LOG_ID=?
-- Parameters --
p[1] = {pd: streetAddr2} Des 2 (java.lang.String)
p[2] = {pd: city} Des Plaines2 (java.lang.String)
p[3] = {pd} 900001 (java.lang.String)

updateItem(addressValidation_req_log:900001) (changes applied: {streetAddr2=Des 2,city=Des Plaines2})
updateItem(categorytier3info:1335) (changes applied: {createUser=mktg-team1,updateUser=mktg-team1})

 UPDATE WWW_CONTACTUS_DTL
    SET CREATE_USER=?,UPDATE_USER=?
  WHERE SUB_CATEGORY_ID=?
-- Parameters --
p[1] = {pd: createUser} mktg-team1 (java.lang.String)
p[2] = {pd: updateUser} mktg-team1 (java.lang.String)
p[3] = {pd} 1335 (java.lang.Integer)

=============================================================================================
Case 4: What happens if setPropertyValue is called on item - With Transaction, with UpdateItem?
update query is fired for each item when updateItem is called, but changes got updated in database only
when transaction is commited.

Note: The difference between case 3 and case 4 is, in case 3 all update queries are fired and committed when transaction ends. In case 4 update queries are fired during updateItem call and commit will be done only at the end of the transaction.

For example:

MutableRepositoryItem mutItem = repo.getItemForUpdate("900001", "addressValidation_req_log");
mutItem.setPropertyValue("city", "Des Plaines2");
mutItem.setPropertyValue("streetAddr2", "Des 2");
repo.updateItem(mutItem);

MutableRepositoryItem mutItem1 = repo1.getItemForUpdate("1335", "categorytier3info");
mutItem1.setPropertyValue("createUser", "mktg-team1");
mutItem1.setPropertyValue("updateUser", "mktg-team1");
repo1.updateItem(mutItem1);

In logs -
setPropertyValue(addressValidation_req_log:900001.city,Des Plaines2)
setPropertyValue(addressValidation_req_log:900001.streetAddr2,Des 2)
 UPDATE www_addr_verify_req_log
    SET STREET_ADDR2=?,CITY=?
  WHERE REQUEST_LOG_ID=?
-- Parameters --
p[1] = {pd: streetAddr2} Des 2 (java.lang.String)
p[2] = {pd: city} Des Plaines2 (java.lang.String)
p[3] = {pd} 900001 (java.lang.String)
updateItem(addressValidation_req_log:900001) (changes applied: {streetAddr2=Des 2,city=Des Plaines2})

setPropertyValue(categorytier3info:1335.createUser,mktg-team1)
setPropertyPD{categorytier3info,1335,updateUser} = mktg-team1 (java.lang.String)
 UPDATE WWW_CONTACTUS_DTL
    SET CREATE_USER=?,UPDATE_USER=?
  WHERE SUB_CATEGORY_ID=?
-- Parameters --
p[1] = {pd: createUser} mktg-team1 (java.lang.String)
p[2] = {pd: updateUser} mktg-team1 (java.lang.String)
p[3] = {pd} 1335 (java.lang.Integer)
updateItem(categorytier3info:1335) (changes applied: {createUser=mktg-team1,updateUser=mktg-team1})
=============================================================================================
Hope this helps!!