Question : sql missing values
Answered by : vastemonde
-- Find missing t1 values in t2 (based on 'id' field)
SELECT * FROM t1 WHERE t1.id NOT IN (SELECT id FROM t2);
-- or
SELECT * FROM t1 WHERE NOT exists ( SELECT NULL FROM t2 WHERE t2.id = t1.id
);
-- or
SELECT t1.* FROM t1 LEFT OUTER JOIN t2 ON t2.id = t1.id WHERE t2.id IS NULL;Source : | Last Update : Thu, 29 Apr 21
Question : Select the number of missing values in column SQL
Answered by : elisabeth-engering
-- You can check for NULL values using the expression IS NULL:
SELECT COUNT(*)
FROM example_table
WHERE example_column IS NULL;Source : https://campus.datacamp.com/courses/introduction-to-sql/filtering-rows?ex=10 | Last Update : Wed, 27 Jul 22
Question : Select the number of non-missing values in column SQL
Answered by : elisabeth-engering
-- You can check for not NULL values using the expression IS NOT NULL:
SELECT COUNT(*)
FROM example_table
WHERE example_column IS NOT NULL;Source : https://campus.datacamp.com/courses/introduction-to-sql/selecting-columns?ex=11 | Last Update : Wed, 27 Jul 22