SSIS Equality Operator not working as expected - mysql

Question

I have an SSIS package that is hooked into a MySQL database that has a tinyint(1) field which is set to the value 4 and I'm checking to see if that value is 4 in the database because it should not change based on the incoming flat file if it is already set to 4, but it doesn't seem to be working.
It should not be updating the status because the field is set to 4 but I guess I just don't understand why the expression isn't working. I have tried all the different int types for SSIS and it doesn't matter because it always sets the status to 1. Based on a quick google search a tinyint should be an unsigned 1 byte int which is why I am casting it to DT_UI1
Incoming values from flat file the first being the product and the last being the status
"039414","*****","*****","*****","*****","*****","*****","*****"," "
Existing value from the database the first being the product and the second being the status
039414 4
I handle the status by the following derived column expression, basically if there is no value it should be 1 otherwise it should be 4
LEN(TRIM(Status)) > 0 ? (DT_UI1)4 : (DT_UI1)1
Here is the derived column expression that I'm using to set the product_status (products_status being the actual field from the database and prod_status the status from the incoming flat file):
((DT_UI1)products_status == (DT_UI1)4) || ISNULL(prod_status) ? (DT_UI1)4 : (DT_UI1)prod_status
What I'm expecting to happen is a few products should keep their status of 4 but are being updated to 1, does anyone have an idea why?
Edit:
I tried changing the expression to the following with no success.
(DT_UI1)products_status == (DT_UI1)4 || ISNULL(prod_status) ? (DT_UI1)4 : (DT_UI1)prod_status
and
((DT_UI1)products_status == (DT_UI1)4 || ISNULL(prod_status)) ? (DT_UI1)4 : (DT_UI1)prod_status
and just the base test
(DT_UI1)products_status == (DT_UI1)4 ? (DT_UI1)4 : (DT_UI1)prod_status
Solution:
I ended up casting the field in the query to an integer because it was being pulled in as a boolean instead of an int
CAST(products_status AS SIGNED)
Then changed my expression to the following and it worked as expected
(products_status == 4 || ISNULL(prod_status)) ? (DT_I4)4 : prod_status

Answer 1

Not sure about the precedence here, but don't you think you want extra parentheses around the condition in the immediate if:
( ((DT_UI1)products_status == (DT_UI1)4) || ISNULL(prod_status) ) ? (DT_UI1)4 : (DT_UI1)prod_status
Looks like it might otherwise return "true", which is sometimes rendered as 1.
UPDATE
Here is a link to Data Viewer which lets you see what values SSIS is assigning to the columns and helps you analyze situations like this.

Answer 2

Your original expression
((DT_UI1)products_status == (DT_UI1)4) || ISNULL(prod_status) ? (DT_UI1)4 : (DT_UI1)prod_status
returns a boolean. Let's assume products_status is 4 and prod_status is also set to 4.
((DT_UI1)products_status == (DT_UI1)4)
Evaluates as TRUE.
ISNULL(prod_status) ? (DT_UI1)4 : (DT_UI1)prod_status
Evaluates as 4.
Your original expression now evaluates as
TRUE || 4
Which evaluates to
TRUE
Which when you try to stick it in an integer column like products_status becomes 1.
Your first revision makes no substantive change to the evaluation chain and also returns TRUE (i.e. 1).
Your second revision is the correct formulation of the ternary operator, as is the final base test. However, it appears that ISNULL(prod_status) always returns FALSE in your case since you are explicitly setting it to 4 or 1 in your other derived column, so let's ignore your second revision and just go to your final base test.
With regards to your final base test, I would definitely:
Attach a Data Viewer before your Derived Column component to ensure that the products_status column being passed in is indeed set to 4
Set a Data Viewer after your Derived Column component to see that products_status has been set (or not set) properly;
Make sure that you properly mapped the products_status field to your database destination and not the prod_status field by mistake.