Select 来自拥有超过 5 个标题的用户的唯一名称。 SQL

Question

DB is H2(in-memory).

There are two tables: Users with id, name, surname . And Documents with id, title, text, user_id .

user_id is a foreign key from Users id .

The task is: Select a unique name from Users that have more than 5 titles.

I created this select, but it gives an error:

SELECT DISTINCT users.name, documents.user_id,
                 ( SELECT COUNT(*)
                   FROM documents AS d
                   WHERE d.user_id = documents.user_id
                     )
                     AS rn
FROM documents, users WHERE users.id = documents.user_id
GROUP BY documents.user_id AND users.name having rn > 5 ORDER BY documents.user_id, users.name, rn;

Error: [22018][22018] Data conversion error converting "Douglas"; SQL statement: SELECT DISTINCT users.name, documents.user_id, ( SELECT DISTINCT COUNT(*) FROM documents AS d WHERE d.user_id = documents.user_id...

(Douglas is a first row name from a table)

Help me to resolve this problem, and find a mistake.

Answer 1

GROUP BY documents.user_id AND users.name

SQL is trying to resolve the boolean expression documents.user_id AND users.name and cannot reconcile what integer and string is supposed to be.

Separate multiple columns in a group by with a comma.

group by documents.user_id, users.name