Previously we use to check the option truncate table but when ever we use to load data into target our previous data used to be deleted and current data used to be inserted.
Now we deal with all the historical and current data. In this SCD type 1 historical data is overwritten with current data. So as a result we do not maintain history but we maintain only current data.
In this SCD type 1 all the historical data is lost as a result.
- Create a mapping and name it.
- Drag Emp source into the mapping area.
- Create a Lookup transformation on target table.
- On Primary key columns you should define your condition, because its the matching column between source and target.
- Create an Expression, drag the ports from lookup transformation and name as prev record. This tells us that records are old ones which are used to compare with new ones.
- Drag the comparision keys from source qualifier to Expression.
- Create two ports as Newflag and Changedflag and give syntax as Isnull (Cust_key) and Not Isnull(Cust_key) and (Prev_Empn != Empno OR Prev_Ename != Ename OR Prev_Sal != Sal)
- First syntax will check for nulls. If there are null, lookup will insert data into the target table.
- Second syntax will check for existing rows. If there are rows, lookup will update data into the target table.
- Create Filter1 and drag all the ports from source qualifier and give filter condition as NEWFLAG
- Connect update strategy and give the 'Update Strategy Expression' as DD_INSERT
- Create Filter2 and drag Cust key from expression and comparision keys from source and give filter condition as CHANGEFLAG
- Connect update strategy and give the 'Update Strategy Expression' as DD_UPDATE
- Make two instances of target, Connect update strategy 1 to target 1 and update strategy 2 to target 2.
- Connect Seq Gen to the cust_key column of target
- Final mapping looks like below screen shot
Note 1 : Lookup condition should be on logical key column
Note 2 : lookup transformation should contain Logical key, Primary key & Comparison key columns.
Note 3 : Second pipeline in the mapping contains comparison key, primary key & changed flag columns.
Note 4 : Expression transformation should contain only primary key, comparision keys along with related source keys and new and changed flag.
Now we deal with all the historical and current data. In this SCD type 1 historical data is overwritten with current data. So as a result we do not maintain history but we maintain only current data.
In this SCD type 1 all the historical data is lost as a result.
- Create a mapping and name it.
- Drag Emp source into the mapping area.
- Create a Lookup transformation on target table.
- On Primary key columns you should define your condition, because its the matching column between source and target.
- Create an Expression, drag the ports from lookup transformation and name as prev record. This tells us that records are old ones which are used to compare with new ones.
- Drag the comparision keys from source qualifier to Expression.
- Create two ports as Newflag and Changedflag and give syntax as Isnull (Cust_key) and Not Isnull(Cust_key) and (Prev_Empn != Empno OR Prev_Ename != Ename OR Prev_Sal != Sal)
- First syntax will check for nulls. If there are null, lookup will insert data into the target table.
- Second syntax will check for existing rows. If there are rows, lookup will update data into the target table.
- Create Filter1 and drag all the ports from source qualifier and give filter condition as NEWFLAG
- Connect update strategy and give the 'Update Strategy Expression' as DD_INSERT
- Create Filter2 and drag Cust key from expression and comparision keys from source and give filter condition as CHANGEFLAG
- Connect update strategy and give the 'Update Strategy Expression' as DD_UPDATE
- Make two instances of target, Connect update strategy 1 to target 1 and update strategy 2 to target 2.
- Connect Seq Gen to the cust_key column of target
- Final mapping looks like below screen shot
Note 1 : Lookup condition should be on logical key column
Note 2 : lookup transformation should contain Logical key, Primary key & Comparison key columns.
Note 3 : Second pipeline in the mapping contains comparison key, primary key & changed flag columns.
Note 4 : Expression transformation should contain only primary key, comparision keys along with related source keys and new and changed flag.
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