Calculating distinct count of ID's while meeting either or condition

[TBSST]

Hi all, 

I am trying to get a distinct total for a card visualtions of ID's that have met either or one of the conditions. My issue is arrising as the conditions sit across different tables and i am unsure how to combine them together without double counting the ID's. 

Example: 

Table 1		Table 2			Table 3
ID		ID	Type1		ID	Type2
1		1	1		1	a
2		1	2		2	a
3		2	1		2	a
4		3	1		3	b
5		4	2		4	b
6		5	1		4	a
7		5	1		5	b
8		6	2		6	a
		7	1		6	b
		8	1		7	a
					7	a
					7	b
					8	a
					8	b
					8	b

I am wanting to count the distint number of ID's that have had at least one Type 1 '1', and/or at least one Type2 'a'. The ID can have both Types, or just one Type to be counted, although the ID should not be counted twice if they have both. 

Any help would be appreciated. 

Thank you. 

[tamerj1 · Accepted solution]

Hi @TBSST 

Please try

ID Count =
COUNTROWS (
    DISTINCT (
        UNION (
            CALCULATETABLE ( VALUES ( Table2[ID] ), Table2[Type1] = "1" ),
            CALCULATETABLE ( VALUES ( Table3[ID] ), Table3[Type2] = "a" )
        )
    )
)