Macro Help

Where is the macro set exactly? Also, the ItemID is probably some ID, right? Why are you assigning a string to it (using the apostrophes) - the HospitalName field name does not sound it holds an integer value and you are also using the + sign to contcatenate strings?

Juraj,

The Macro is being set in the default value for the address field. ItemID is the Key field for the custom table . HospitalName field is a drop down with id as value and Hospital name as name. I concatennated the } because when I didnt it ended the macro there instead of showing the rest.

Thanks for the details. In the WHERE clause, you use standard SQL syntax. So, if you are comparing an integer value, do not use apostrophes, which are for strings. There should be just like: "ItemID = 5" - where the 5 should be the result of the inner expression. So, the macro should look like this:
{%GlobalObjects.CustomTables["customtable.yourtable"].Items.Where("ItemID =" + Field.Value).FirstItem.ReturnValueFieldName#%}

However, the issue here is that the macro in default value is evaluated only once, when the field is rendered, due to performance. So, if you change the value in the other field, it has no effect. In this case it would be better to create a custom form control (portal engine) or form component (MVC/Core development model) which will consists of two fields and you will handle the logic in the code and dynamically load the values as you need. Or, if you will use it as a drop down list and use the macro to fill out the list or, maybe just as a label.