inner-join

This question already has answers here : Closed 5 years ago . ORA-00979 not a group by expression (8 answers) I am new to sql, any help is appreciated. I have two tables, employees and jobs . employees contain a variable job_id (multiple employees can have the same job_ID). jobs contain variables job_id and job_title (one job_ID correspond to one job_title, this is the hr schema in oracle if you are interested). I want the query to return: the job_title, job_ID and the number of people who have the same job_Id. I tried the following code: select j.job_title, e.job_ID, count(e.job_ID) from

I want to do something like this in my domain/entity object : @Entity @NamedQueries({ @NamedQuery(name="favouriteCats", query="from Cat c inner join on UserCat uc where uc.isFavourtie = true and uc.user = :user") }) public final class Cat extends BaseTable So that in my service layer I can do this : Query query = session.getNamedQuery("favouriteCats") query.setParameter(0, MyUser); return query.list(); However, my syntax in HQL is incorrect - and aftern ten minutes looking at official docs I have decided to give up and ask here ... ? My usercat table is joined like so : @ManyToOne(cascade =

I mistyped a query today, but it still worked and gave the intended result. I meant to run this query: SELECT e.id FROM employees e JOIN users u ON u.email=e.email WHERE u.id='139840' but I accidentally ran this query SELECT e.id FROM employees e JOIN users u ON u.email=e.email AND u.id='139840' (note the AND instead of WHERE in the last clause) and both returned the correct employee id from the user id. What is the difference between these 2 queries? Does the second form only join members of the 2 tables meeting the criteria, whereas the first one would join the entire table, and then run the

I have a simple model class User has_many :logs class Logs related in the usual way through the foreign key logs.user_id. I'm trying to do the following using Arel and according to the Arel doc it should work. u_t = Arel::Table::new :users l_t = Arel::Table::new :logs counts = l_t. group(l_t[:user_id]). project( l_t[:user_id].as("user_id"), l_t[:user_id].count.as("count_all") ) l_t.joins(counts).on(l_t[:id].eq(counts[:user_id])) When I do that I get the error TypeError: Cannot visit Arel::SelectManager However the author of Arel explicitly suggests that Arel can do this kind of thing. Please

I am wondering whether CROSS JOIN can be safely replaced with INNER JOIN in any query when it is found. Is an INNER JOIN without ON or USING exactly the same as CROSS JOIN ? If yes, has the CROSS JOIN type been invented only to express intent better in a query? An appendix to this question would be: Can there be a difference using modern and widely used DBMSes when using CROSS JOIN ... WHERE x , INNER JOIN ... ON ( x ) or INNER JOIN ... WHERE ( x ) ? Thank you. In all modern databases all these constructs are optimized to the same plan. Some databases (like SQL Server ) require an ON condition

I want to be able to inner join two tables based on the result of an expression. What I've been trying so far: INNER JOIN CASE WHEN RegT.Type = 1 THEN TimeRegistration ELSE DrivingRegistration AS RReg ON RReg.RegistreringsId = R.Id RegT is a join I made just before this join: INNER JOIN RegistrationTypes AS RegT ON R.RegistrationTypeId = RegT.Id This SQL-script does not work. So all in all, if the Type is 1, then it should join on the table TimeRegistration else it should join on DrivingRegistration . Solution: In my select statement I performed the following joins: INNER JOIN