tblCurrent
 Ref  | CustomerID | ... .. .. .  . |
X001
X002
X003


tblHistorical
 Ref   | ... .. .. .  . |  Missing | Matched
X001   | ... .. .. .  . |  TRUE    | FALSE
X001   | ... .. .. .  . |  FALSE   | FALSE
X002   | ... .. .. .  . |  TRUE    | TRUE
X002   | ... .. .. .  . |  TRUE    | FALSE
X003   | ... .. .. .  . |  FALSE   | FALSE
X003   | ... .. .. .  . |  TRUE    | TRUE

SELECT  a.ref,
        SUM(CASE WHEN b.Missing = 'True' THEN 1 ELSE 0 END) missingTrue,
        SUM(CASE WHEN b.Missing = 'False' THEN 1 ELSE 0 END) missingFalse,
        SUM(CASE WHEN b.Matched = 'True' THEN 1 ELSE 0 END) matchTrue
FROM    tblCurrent a
        LEFT JOIN tblHistorical b
            on a.ref = b.ref
GROUP BY a.ref

SELECT R.Ref,
SUM(CASE WHEN H.Missing = TRUE THEN 1 ELSE 0 END) as MissingTrue,
SUM(CASE WHEN H.Missing = FALSE THEN 1 ELSE 0 END) as MissingFalse,
SUM(CASE WHEN H.Matched = TRUE THEN 1 ELSE 0 END) as MatchedTrue
FROM tblRef R JOIN tblHistorical H
ON R.Ref = H.Ref

SELECT R.Ref,
SUM(CASE WHEN H.Missing = TRUE THEN 1 ELSE 0 END) as MissingTrue,
SUM(CASE WHEN H.Missing = FALSE THEN 1 ELSE 0 END) as MissingFalse,
SUM(CASE WHEN H.Matched = TRUE THEN 1 ELSE 0 END) as MatchedTrue
FROM tblRef R
INNER JOIN tblHistorical H
ON R.Ref = H.Ref
Group by R.Ref

SELECT T.REF,
        COUNT(CASE WHEN H.MISSING = 'TRUE' THEN 1  END) AS MISSINGTRUE,
        COUNT(CASE WHEN H.MISSING = 'FALSE' THEN 1 END) AS MISSINGFALSE,
        COUNT(CASE WHEN H.MATCHED = 'TRUE' THEN 1  END) AS MATCHEDTRUE
FROM   TBLREF T
JOIN   TBLHISTORICAL H
ON     R.REF = H.REF
GROUP BY T.REF