Q:

Union for Columns of Different Datatypes in SQL

I'm using the site (http://www.w3schools.com/sql/sql_union.asp) and I am trying to understand UNION and UNION ALL. A small portion of the "Customers" and "Suppliers" Table is given in the Image below.
I'm confused why when I run the UNION for the Columns City from Customers and PostalCode from Suppliers which are Columns of different datatypes I don't receive an Error. (Seen in Image 2)

Thank You

A:

The definitions of the columns that are part of a UNION operation do not have to be the same, but they must be compatible through implicit conversion. When data types differ, the resulting data type is determined based on the rules for data type precedence. When the types are the same but differ in precision, scale, or length, the result is determined based on the same rules for combining expressions

