How would you reference table1 columns to 2 columns in table 2 I created a table 'State' with 50 exact rows trying to relate (weddingState,contactState) in 'Wedding' table This is the statement that I created but it only joins the top WeddingState correctly - seems not to care about the INNER Join below it... SELECT * FROM weddings...
I am trying to understand how does joins work internally. What will be the difference between the way in which the following two queries would run? For example (A) Select * FROM TABLE1 FULL JOIN TABLE2 ON TABLE1.ID = TABLE2.ID FULL JOIN TABLE3 ON TABLE1.ID = TABLE3.ID And (B) Select * FROM TABLE1 FULL JOIN TABLE2 ON TABLE1.ID = T...
Scenario: Let's say I have two tables, TableA and TableB. TableB's primary key is a single column (BId), and is a foreign key column in TableA. In my situation, I want to remove all rows in TableA that are linked with specific rows in TableB: Can I do that through joins? Delete all rows that are pulled in from the joins? DELETE FROM ...
I am joining three tables (performing a full outer join) so that I can retrieve all the records from all the tables. Problem that I am facing is with the order in which I join tables. Table Information (1) If I join tables in TABLE1, TABLE2, TABLE3 sequence I get two rows for record with team B and Level 1. SELECT DISTINCT (CAS...
I'm using a SQL query that is similar to the following form: SELECT col1, col2 FROM table1 LEFT OUTER JOIN table2 ON table1.person_uid = table2.person_uid AND table1.period = table2.period And it's either way too slow or something's deadlocking because it takes at least 4 minutes to return. If I were to change it to this: SELECT col...
Example Problem: Entities: User contains name and a list of friends (User references) Blog Post contains title, content, date and Writer (User) Requirement: I want a page that displays the title and a link to the blog of the last 10 posts by a user's friend. I would also like the ability to keep paging back through older entries. ...
I am wondering how to differentiate all these different joins ... ...
I have two tables 1) Product 2) Categories Product table has a field called "CategoryID" and the Category table has a field called "CategoryName", ID, DateCreated, and a few others. I want to use LINQ to SQL to query all the Product rows as well as JUST the Category.CategoryName. This query will be used in a datasource and be bound to ...
What exactly does JPA's fetch strategy control? I can't detect any difference between eager and lazy. In both cases JPA/Hibernate does not automatically join many-to-one relationships. Example: Person has a single address. An address can belong to many people. The JPA annotated entity classes look like: @Entity public class Person { ...
Is there a limit to the number of joins permitted in a JPA/Hibernate query? Since Hibernate doesn't automatically join, I have to explicitly specify the joins in my JPA/Hibernate query. For example, person has an address, an address has a state. The following query retrieves person(s) with address and state fully loaded: select p, a, s...
The DBA here at work is trying to turn my straightforward stored procs into a dynamic sql monstrosity. Admittedly, my stored procedure might not be as fast as they'd like, but I can't help but believe there's an adequate way to do what is basically a conditional join. Here's an example of my stored proc: SELECT * FROM table WHERE ( ...
Basically I have a mysql query something like the following: mysql_query("SELECT n.title, v.value FROM posts n INNER JOIN votes v ON n.id = v.id"); And what I need to do is to grab the title from the posts table and the current vote value from the votes table. At the moment, votes aren't stored into the votes table unless a vote happ...
I have an app where I want to link an instance of a model to another instance of the same model via another model (i.e. Task1 > Relationship < Task2) and am wondering if I can use has_many :through for this. Basically, the relationship model would have extra information (type_of_relationship, lag) so it would be ideal to have it as a jo...
I am a somewhat experienced Rails developer and I thought I would try out ASP.NET's version of MVC. In doing so I also decided to try Linq->Sql... I am a bit confused about the way Linq->Sql handles joins. A trivial example of my schema is : books: id title categories: id name books_categories: book_id category_id Simply dragging...
I've embarked on a project which is encouraging me to expand my knowledge of SQL. I've already learned quite a bit, but I've gotten myself to a point where I can see a problem, but I don't know enough to properly research a solution. I've hit SO, Google, and the MySQL docs, but either I'm asking the wrong questions or I don't know how ...
I am trying to stick to the practice of keeping the database normalized, but that leads to the need to run multiple join queries. Is there a performance degradation if many queries use joins vs having a call to a single table that might contain redundant data? ...
Imagine the following tables: create table boxes( id int, name text, ...); create table thingsinboxes( id int, box_id int, thing enum('apple,'banana','orange'); And the tables look like: Boxes: id | name 1 | orangesOnly 2 | orangesOnly2 3 | orangesBananas 4 | misc thingsinboxes: id | box_id | thing 1 | 1 | orange 2 | 1...
Ok, this is a dumb thing that I'm sure I've done dozens of times but for some reason I can't find it. I have an array... And want to get a string with the contents of that array separated by a delimited... Where is the .Join() method that I can't find? (This is .Net 2.0, I don't have any LINQ stuff) Thank you! ...
I have a Task object that has a collection of Label objects ... in the database the tables are called Task and Label. There are a variety of ways to search for a Task, so using LINQ, I construct my LINQ query in an expression tree ... similar to the below code sample: IQueryable<Data.Task> query = ctx.DataContext.Tasks; if (crit...
Hi, I wrote a query select u.user, g.group, u2g.something from users, groups, u2g where users.u = u2g.u and groups.g = u2g.g that returns data like this: user, group, something ---------------------- 1 , 3, a 1 , 5, b 2 , 3, c 3 , 3, d 4 , 5, e now I would like to limit this query in such a way th...