SQL Statement JOIN only returns elements with association
I have Acts by Users who are joined to Groups by Memberships in a PostgreSQL db.
I have a query to generate rows for a leaderboard. However, it currently excludes Users where the Acts table does not include a row with the corresponding
users_id. I want to include all group members, even those with 0 Acts.
The current query:
SELECT acts.users_id, username, avatar_url, COUNT(acts.id) FROM acts JOIN users ON acts.users_id = users.id JOIN memberships on memberships.users_id = users.id WHERE memberships.groups_id = ' + req.params.group_id + ' AND acts.created_at >= (CURRENT_DATE - 6) GROUP BY acts.users_id, username, avatar_url ORDER BY COUNT(acts.id) DESC
I have tried changing
JOIN before users to
RIGHT JOIN and
LEFT JOIN, but I get the same result. At one point, I think
RIGHT JOIN was working, but somehow, I have gone awry.
SQL joins and how to use them, JOINs are clauses in SQL statements that link two tables together, usually based An INNER JOIN returns a result set that contains the common elements of the join table contains only rows where there is a definite match between the values or RIGHT OUTER JOIN that displays all reviews and their associated books, However, I only want to return the results from table 1 that do not match up with the results in table 2. I know this seems simple, but where I'm stuck is the fact that there are multiple rows in table 1 that match up with table 2 (there are multiple intervals for any given hour).
I have had issues like this before. What I would do is remove all the where statements and the joins. Start by left joining the users to acts only and see if the query retains the inactive users that you wanted. Likewise try a left join between users and memberships. Once you have a query of two tables with users that do not exist in the ACT table. Join the third table with the output of the first two. And then finally apply your where statement and group by count.
SQL Inner Join to Two or More Tables, Use it to combine columns from two or more tables via a join condition. Below is an example of simple select statement with an INNER JOIN clause. The only changes are the addition of the WHERE and ORDER BY clauses. By now This query allows us to compare values for each row that matches the Product Name. Introduction to SQL Server LEFT JOIN clause. The LEFT JOIN clause allows you to query data from multiple tables. It returns all rows from the left table and the matching rows from the right table. If no matching rows found in the right table, NULL are used. The following illustrates how to join two tables T1 and T2 using the LEFT JOIN clause:
If you want to return users who don't have acts, you need to start from an other table than acts. You can for exemple try to start from the users table instead of the acts :
SELECT acts.users_id, username, avatar_url, COUNT(acts.id) FROM users LEFT JOIN acts ON acts.users_id = users.id LEFT JOIN memberships on memberships.users_id = users.id WHERE memberships.groups_id = ' + req.params.group_id + ' AND acts.created_at >= (CURRENT_DATE - 6) GROUP BY acts.users_id, username, avatar_url ORDER BY COUNT(acts.id) DESC
This should return you all the users, even if they don't have an acts or a memberships.
4 Ways to Join Only The First Row in SQL, To solve this problem, we need to join only the first row. The subquery will run once for each row in the outer query: and sorts those windows by created_at desc. row_number() returns a row's position within its window. Using SQL DISTINCT. The SQL Distinct command can be used in the SELECT statement to ensure that the query returns only distinct (unique) rows. When the query is selecting the rows it discards any row which is a duplicate of any other row already selected by the query.
Pro JPA 2, It would be useful to return only a subset of the properties from an entity. The result type of a select query cannot be a collection; it must be a single valued a collection association and return elements of that collection, we must join the two Write a SQL statement to display a string "This is SQL Exercise, Practice and Solution". Go to the editor Click me to see the solution with pictorial presentation. 3. Write a query to display three numbers in three columns. Go to the editor Click me to see the solution with pictorial presentation. 4.
SQL Left Join, This SQL statement would return all rows from the company table and only those rows from the foods table where the joined fields are equal Here are the different types of the JOINs in SQL: (INNER) JOIN: Returns records that have matching values in both tables; LEFT (OUTER) JOIN: Returns all records from the left table, and the matched records from the right table; RIGHT (OUTER) JOIN: Returns all records from the right table, and the matched records from the left table
SQL FULL OUTER JOIN Keyword, Note: FULL OUTER JOIN can potentially return very large result-sets! Tip: FULL OUTER JOIN and FULL JOIN are the same. FULL OUTER JOIN Syntax. SELECT SQL Tutorial. Basic SQL. Intermediate SQL. Putting it together. SQL Aggregate Functions. SQL COUNT. SQL SUM. SQL MIN/MAX. SQL AVG. SQL GROUP BY. SQL HAVING. SQL CASE. SQL DISTINCT. SQL Joins. SQL INNER JOIN. SQL Outer Joins. SQL LEFT JOIN. SQL RIGHT JOIN. SQL Joins Using WHERE or ON. SQL FULL OUTER JOIN. SQL UNION. SQL Joins with Comparison