What is an Expression Transform?
Expression is a Passive connected transformation used to calculate values in a single row before you write to the target. We can use the Expression transformation to perform any non-aggregate calculations. We can al-so use the Expression transformation to test conditional statements before you output the results to target tables or other transformations.
For example, we might need to adjust employee salaries, concatenate first and last names, or convert strings to numbers.
|Expression Transformation Interview Question|
How many types of ports are there in Expression transform?
There are three types of ports- INPUT, OUTPUT, and VARIABLE
What is the execution order of the ports in an expression?
All ports are executed TOP TO BOTTOM in a serial physical ordering fashion, but they are done in the following groups:
All input ports are pushed values first.
Then all variables are executed (top to bottom physical ordering in the expression).
Last - all output expressions are executed to push values to output ports