The NULL value handling in comparison operators( =) and logical operators( OR). Conceptually a IN expression is semanticallyĮquivalent to a set of equality condition separated by a disjunctive operator ( OR).įor example, c1 IN (1, 2, 3) is semantically equivalent to (C1 = 1 OR c1 = 2 OR c1 = 3).Īs far as handling NULL values are concerned, the semantics can be deduced from Unlike the EXISTS expression, IN expression can return a TRUE,įALSE or UNKNOWN (NULL) value. In Databricks, IN and NOT IN expressions are allowed inside a WHERE clause ofĪ query. name name age name age - Albert null Albert null Michelle 30 Michelle 30 Fred 50 Fred 50 Mike 18 Mike 18 Dan 50 Dan 50 Marry null Marry null Joe 30 Joe 30 > SELECT * FROM person p1, person p2 WHERE p1. name name age name age - Michelle 30 Michelle 30 Fred 50 Fred 50 Mike 18 Mike 18 Dan 50 Dan 50 Joe 30 Joe 30 - The age column from both legs of join are compared using null-safe equal which - is why the persons with unknown age (`NULL`) are qualified by the join. The persons with unknown age (`NULL`) are filtered out by the join operator. > SELECT * FROM person GROUP BY age HAVING max ( age ) > 18 age count ( 1 ) - 50 2 30 2 - A self join case with a join condition `p1.age = p2.age AND p1.name = p2.name`. > SELECT * FROM person WHERE age > 0 OR age IS NULL name age - Albert null Michelle 30 Fred 50 Mike 18 Dan 50 Marry null Joe 30 - Person with unknown(`NULL`) ages are skipped from processing. > SELECT * FROM person WHERE age > 0 name age - Michelle 30 Fred 50 Mike 18 Dan 50 Joe 30 - `IS NULL` expression is used in disjunction to select the persons - with unknown (`NULL`) records.
Persons whose age is unknown (`NULL`) are filtered out from the result set.
REFRESH (MATERIALIZED VIEW or STREAMING TABLE).REFRESH FOREIGN (CATALOG, SCHEMA, or TABLE).Federated queries (Lakehouse Federation).Privileges and securable objects in the Hive metastore.Privileges and securable objects in Unity Catalog.
0 kommentar(er)
