SQL Left Join: Condition on where clause or on clause

As a database developer, we know about SQL left, right or inner join clearly. But when it comes to left join or right join with condition putting on where clause or on clause can make big  difference that we sometimes overlook or get panic why those making difference.

I will go directly to the example, e.g. we have Account and Customer table and we want all the accounts those are exist in Account table and also consider if any customer is added on '2013-05-27', we take him as well.

Here we have Account and Customer table and data look like below:

Account
Account_No	Status	Eff_DT	Customr_ID
123	actv_	21-05-2014	301
124	actv_	22-05-2014	307
125	actv_	23-05-2014	303
Customer
Customer_ID	Customer_Name	Eff_DT
301	john	21-05-2014
302	san	21-05-2014
303	paul	22-05-2014
304	helle	23-05-2014
305	jon	24-05-2014
SQL Query :
select Account_no, status,A. eff-dt, A.customer_id, Customer_Name  from ACCOUNT as A
join customer as C on A.customer_id=C.customer_id
Result Set:
Account_No	Status	Eff_DT	Customr_ID	Customer_Name
123	actv_	21-05-2014	301	john
124	actv_	22-05-2014	307	null
125	actv_	23-05-2014	303	paul
Changes the query with 'on' clause:
select Account_no, status,A. eff-dt, A.customer_id, Customer_Name, C.EFF_DT as Customer_EFF_DT  from ACCOUNT as A
join customer as C on A.customer_id=C.customer_id
and C.eff_dt= date '2013-05-24'
Result will look like:
Account_No	Status	Eff_DT	Customr_ID	Customer_Name	Customer_EFF_DT
123	actv_	21-05-2014	301	john	null
124	actv_	22-05-2014	307	null	null
125	actv_	23-05-2014	303	paul	null
Changes the query with 'Where' clause
select Account_no, status,A. eff-dt, A.customer_id, Customer_Name, C.EFF_DT as Customer_EFF_DT  from ACCOUNT as A
join customer as C on A.customer_id=C.customer_id
where C.eff_dt= date '2013-05-24'
Result will return nothing
It means where clause filter after join has established. When we did same condition   C.eff_dt= date '2013-05-27' on clause it was still under left join on condition
and that returns you data as how left join work. But where clause work after making join,  if we look at the last result, consider we are implying where clause on the last record set.