Oracle 11g Release 2

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CREATE TABLE Table1 (ID varchar2(2), Flag int, Name varchar2(4));
INSERT ALL 
    INTO Table1 (ID, Flag, Name) VALUES ('1X', 1, 'Y')
    INTO Table1 (ID, Flag, Name) VALUES ('2Y', 0, NULL)
    INTO Table1 (ID, Flag, Name) VALUES ('3Z', 1, NULL)
    INTO Table1 (ID, Flag, Name) VALUES ('4A', 1, 'Y')
SELECT * FROM dual;
4 rows affected

CREATE TABLE Table2 (B_ID varchar2(2), City varchar2(4), State varchar2(4));
INSERT ALL 
    INTO Table2 (B_ID, City, State) VALUES ('1X', 'Y', NULL)
    INTO Table2 (B_ID, City, State) VALUES ('2Y', NULL, NULL)
    INTO Table2 (B_ID, City, State) VALUES ('3Z', NULL, 'Y')
    INTO Table2 (B_ID, City, State) VALUES ('4A', 'Y', 'Y')
SELECT * FROM dual;
4 rows affected

SELECT COUNT(*) Total_Count,	
       COUNT(CASE WHEN t1.Name IS NULL OR t2.City IS NULL OR t2.State IS NULL THEN 1 END) Ids_having_null,	
       AVG(CASE WHEN COALESCE(t1.Name, t2.City, t2.State) IS NOT NULL THEN 1 ELSE 0 END) Percentage_missing
FROM Table1 t1 INNER JOIN Table2 t2
ON t2.B_ID = t1.ID;


TOTAL_COUNT
IDS_HAVING_NULL
PERCENTAGE_MISSING


4
3
.75