For example, you can resolve problem by this statement:

select case when exists(select null from <table_name>) then 1 else 0 end as colA from dual

This statement still brings error - became not supported:SQL query returned empty result

2.0.* supports empty values for string, text, log items !

Does it really sound like a bug ?

Still the same on 3.0 version. Empty value for String and Characters should be allowed.

It's actually allowed.

mbsit, when you say that it is "the same", how have you configured the item and what errors do you get ?
as zalex_ua mentioned, empty values for character/text types have been allowed for a long time now.

v. 3.0.4

and configuration:

Bests,
Grzegorz

Type of information Text allows to receive and store an empty value.
What is error message for the item status?

The error is on the screen you have to scroll horizontally my screenshot.

"SQL query returned empty result."

ODBC isql returns from this query:

+---------------------------------------------------------------------------------+-----------+--------------------+-----------------------------------------+
| xxxxxxxxxxxx                                                                        | xxxxxxxx| xxxxxxxx         | xxxxxx                                      |
+---------------------------------------------------------------------------------+-----------+--------------------+-----------------------------------------+
+---------------------------------------------------------------------------------+-----------+--------------------+-----------------------------------------+
SQLRowCount returns -1
SQL>

Bests,
Grzegorz

Ahh, cool.

Well, "empty result" for an ODBC check in not the same like "empty value" to be stored in zabbix db.
ODBC check supposes to get at least one row, which looks in not the case for you!

So I will better say: "Empty result from ODBC should be allowed for String and Character data in Zabbix"

My statement (assumption actually) above based on these 3 lines from doc :

The query must return one value only.
If a query returns more than one column, only the first column is read.
If a query returns more than one line, only the first line is read.

https://www.zabbix.com/documentation/3.0/manual/config/items/itemtypes/odbc_checks

But "magic" suggested by Alexander in very first comment could help you to find a workaround. Maybe the SQL have to adjusted for monitored DB engine.

well, I'd suggest you to create a new clean ZBXNEXT, mentioning this ZBX as a reference.
Any objections to close this one ?

No, I will this might be close, tnx.

Closed as won't fix.
Not empty "Fix version" should be ignored.