Hi Asma,
Here's a practical use for KEEP. Imagine you have a source table of customers and a source table of orders that you don't want to combine into one table in your QV model.
You want to load all orders for product ABC bought by customers from Country XYZ.
Let's 'keep' things simple and say there is only one product per order.
If you try
Customers:
LOAD
CustomerID,
.
.
Resident customers WHERE Country = XYZ;
Orders:
LOAD
CustomerID,
.
.
Resident Orders WHERE Product = ABC;
This will load Customers who may not have bought ABC and you may have orders for product ABC with no corresponding Customer record because these orders were bought from a country other than XYZ.
Instead if you try
Customers:
LOAD
CustomerID,
.
.
Resident customers WHERE Country = XYZ;
Orders:
Inner Keep(Customers)
LOAD
CustomerID,
.
.
Resident Orders WHERE Product = ABC;
Qlikview will drop records from Customers who did not order product ABC and will only load Orders placed by Customers from XYZ.
It's exactly like an inner join except the two tables are not combined in the data model.
You can replace Inner Keep(Customers) with Left Keep(Customers) then no customer records will be removed and only orders for ABC associated with these customers will load.
Right Keep(Customers) will load all orders for product ABC but only customers who bought ABC will be remain in the Customers table.
All this is analogous to Inner, Left and Right Joins except the tables are kept separate.
Cheers
Andrew
