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CASE
WHEN T0.MONTH||DAY exists in T1.MONTH||DAY THEN T1.Birthday
ELSE WHEN T0.YEAR||MonTH exists in T2.YEAR||MONTH THEN T2.Remarks
ELSE 'No entry found'
END AS FIELDMERGE

SELECT
T0."Year",
T0."Month",
T0."Day",
CASE
WHEN T0."Month" || T0."Day" = T1."Month" || T1."Day" THEN
T1."Birthday"
WHEN T0."Year" || T0."Month" = T2."Year" || T2."Month" THEN
T2."Remarks"
ELSE
'No value'
END AS MERGEFIELD,
T1."Birthday",
T2."Remarks"
FROM
User1."0_Calendar" T0
LEFT JOIN User1."2_month" T2 ON T2."Year" = T0."Year"
AND T2."Month" = T0."Month"
LEFT JOIN User1."1_birthday" T1 ON T1."Month" = T0."Month"
AND T1."Day" = T0."Day"