hai

 i guess this question comes under scd's itseems,
becoz in scd type1 we will overwrite the oldvalue with new 
value.here we dont have any history

u can get this "update override" by double clicking or right
clicking the target .

Hi,

i guess the SQL override is used in the source qualifier trf
to implement joins, filter, sorter etc..

but update override is used in the Target table definition.
u use this option to update Targets that have no primary 
key (hence u can't use update strategy) coupled 
with 'Update as update' property in the session mappings tab
and 'Treat rows as' property set as 'Update' in the session
Properties tab.

hi,

sorry for a small mistake in the last answer

u use 'update else insert' property in the session mappings 
tab.

Update Override it is an option available in TARGET 
instance.By defalut Target table is updated based on 
Primary key values.To update the Target table on non 
primary key values u can generate the default Querey and 
override the Querey according to the requiremnet.Suppose 
for example u want to update the record in target table 
When a column value='AAA' then u can include this condition 
in where clause of default Querey.

Coming to SQL override  it is an option available in Source 
Qualifier and Lookup transafornmation where u can inlude 
joins ,filters,Group by and order by.

In the case of source qualifier when we use sql override 
opition we will get query with our alias name and when we 
user update transformation override when we enter update 
override we will get column names with alias name


In update transformation order by clause is default that is 
not in sql over ride(According to my knowledge)
  
If i am wrong plz correct me to my mail-id.....