Expression rule for multiple table

Question

Hi, 
 
 can we write single expression rule to get data from multiple table, if it's possible how it can be simple example 
 like: select orders.orderid, customers.custername from order inner join customers on orders.customerid=customer.customerid 
 can we write such query in expression rule 
 Thanks, 
 Kavya

Stewart Burchell · Accepted Answer

In your conceptual model you need to separate the data model aspect from the data retrieval aspect. Expressions can retrieve data from a "data model" but not (easily) implement such a model. 
 In your example you have two choices: 
 
 create two different Record Types, one for Order and one for Customer, and then have Orders nested as a multiple under Customer. You can then use a!queryRecordType() to retrieve the data 
 create a database VIEW which joins the data as you describe, then create a CDT from the VIEW and then an expression that contains a a!queryEntity() that retrieves data from that VIEW 
 
 Note that 1., is essentially Appian's way of effectively implementing 2. without having to resort to creating database VIEWs.

Harshit Bumb (Appyzie) · Answer

Hi there, 
 Stewart Burchell has already told you the two ways. Another approach can be to query 2 different tables by passing the output of one QE into another as input and then combining the result in a third expression rule. However, I would still prefer creating records and then using record relationships.

Expression rule for multiple table

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