Inner join, left Outer Join and association Difference

The source code for the CDs view of the test, line 8th joins the TJ02T with the inner join, which holds the ID and description of all system states.

Inner Join test results: For those States that do not maintain descriptive information in the TJ02T, they do not appear in the result set.

Change the inner join of line eighth to outer join, and the test result is the opposite: Notice that the row items with a stat column value of E0001 also appear in the result set.

Association test results are consistent with the left Outer join.

The underlying implementation of association is actually consistent with the left Outer join. There are two ways to verify this conclusion.

Method 1

Previewing a CDs view with the association implementation in ABAP Development Studio enables the tool to discover that the association was finally implemented through a left Outer join.

Method 2

This button in the transaction code ST05: shows the execution plan, and also shows that the association bottom is implemented by the left Outer join.

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Inner join, left Outer Join and association Difference