Expression

An expression a SQL expression based one or more values, operators, and SQL functions that evaluate to a boolean value.

Expression check validate the SQL expression to identify the data in base table column matches with the expression. the failed values will falg as a data quality issue

  • SQL expression must be compliant with the target cloud warehouse
  • For example:

If the base table is LINEITEM, base column is L_SHIPMODE, then the expression check is defined as,

  • (not exists (select L_SHIPMODE from LINEITEM where substr(NVL(L_SHIPMODE,’X’),1,3)=’AIR’)).

Here, if the LINEITEM.L_SHIPMODE column value does not match with specified expression check then those base table records are considered as invalid.

Steps to create expression check rule in uArrow:

1 Click + Add button in the expression check rule for column L_SHIPMODE.

2 Do the following, In the expression section for rule.

* Column : Choose the expression column.
* Rule Description : Fill the description.
* Rule Category : Choose or create new dimension to classify rule if required.
* Sql Expression : Fill the expression sql.
* Clink on Verify button and it will validate expression sql rule.
* Clink on save button

Below is the window with values populated for expression check.

Finally verify and apply your changes. and then save the job.

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