Mysql – Query outer join fixed values
I would like to query some IDs (fixed values) into a table, like a "outer join" with the mandatory fields should be the fixed values. I have to do the same for SQLServer and MySQL, but with one solution I…
Select only a row if one of the joined columns meets both conditions in Postgresql
Please suppose these two tables: users table: id account_id 1 1 2 1 3 1 4 1 user_labels table: id user_id title 1 2 label1 2 2 label2 3 1 label1 4 1 label2 now I want to select users…
Postgresql – What are the semantics of "from_item is not null" / "from_item is null"?
Given the following query select * from jsonb_to_recordset('[{"a":1},{"a":2,"b":42}]') i(a int, b int) where i is not null I observe the result of a single row, which is the one where both columns are non-null. When negating the where clause to…
Mysql – Why is this left outer join include rows twice?
In the following case: CREATE TABLE Persons ( groupId int, age int, Person varchar(255) ); insert into Persons (Person, groupId, age) values('Bob' , 1 , 32); insert into Persons (Person, groupId, age) values('Jill' , 1 , 34); insert into Persons…