Joins in Dynamics 365 Finance and operation | X++ Joins

Joins in Dynamics 365 Finance and Operations typically refers to the process of combining data from two or more related entities in a query or a report. These joins are commonly used in retrieving data from multiple tables or entities within the Dynamics 365 system.

The primary purpose of using joins in Dynamics 365 is to fetch related data across different entities or tables in a single query. This allows users to gather comprehensive information that spans multiple aspects of their business processes.

For example, if you're working with Dynamics 365 Finance and Operations, you might want to retrieve information about customers and their associated orders. In this scenario, you would use a join operation to combine data from the "Customer" entity/table and the "Order" entity/table based on their common fields such as customer ID.

By utilizing joins, users can create reports, dashboards, or perform complex queries that involve data from various parts of the Dynamics 365 system. This capability enhances the ability to analyse relationships and dependencies between different entities, providing a more holistic view of business operations.

T- SQL Joins

Any code associated with database is written in X++ will end up running a SQL statement against the database. So before learning D365 Joins you must have a look in to SQL Joins,

In T- SQL we have the following joins,
Inner Join – returns row when there is a match in both tables.
Left Join – returns all rows from the left table, even if there are no matches in the right table.
Right Join – returns all rows from the right table even if there are no matches in the left table.
Full Outer Join – returns all rows when there is a match in one of the tables.
Self-Join – used to join a table to itself, as if the table were two tables.
Cross Join – is a type of join operation that combines each row from one table with every row from another table.

D365 X++ Joins

In Dynamics 365 Finance and Operations, X++ joins really support only four type of joins, developer can write x++ codes very similiter to T-SQL code to retrieve the data. I will explain the four types of joins and its similarity to T-SQL joins,

• Join - Join keyword in X++ is used to returns row when there is a match in both tables. Which is same as inner join in T-SQL, but only one thing is keyword “inner” is not used with X++ join. But the effect is same, which will retrieve a row when there is a match in both tables.
• Outer Join – this will returns all rows from the left table, even if there are no matches in the right table. Which is same as Left join in T-SQL,

Note: There is not right join in x++. However, a developer can just change which table is first, and which table is second to come up with the same result as a right join.

• Exists join – this is another type of join, which is like Join in X++, but only the difference is, it will only retrieve only one number of records from the first table even though more than one match found in the second table. if there are many matching records in the second table, the number of rows in the result set will not increase. The system will stop looking after it finds one match in the second table. 

Note: don’t confuse the keyword Exists with T-SQL, in T-SQL Exists keyword is used for another purpose.

• NotExists join – the keyword NotExists join is used to retrieve a row in the first table if there does not exist a match in the second table.

In the next article we willexplain each and every joins in dynamics 365 fo in detail with examples. if this article is usefull, try to share to your friends and colllegues.