I am trying to answer your question as I found it interesting.
I think you are a very new to SQL and you are trying to convert the column containing that appears to me as a character values to the int values
As your value is not the valid INT so you are facing above mentioned error. You need to consider many things to avoid such errors.
Is your column supposed to be a char or varchar data type and if that is so then are the non integer characters also expected or allowed in your data?
If this is not the case then:
1. Have some incorrect data entered by somebody in your test data?
2. Why this is not the int column to make your DB enforce this thing
If this is the case then why are you casting it to the int?
· Is your table which you are joining to is also using the integer identifier?