join

Mulitple full joins in Postgres is slow

I have a program to use the IMDB database and am having very slow performance on my query. It appears that it doesn't use my where condition until after it materializes everything. I looked around for hints to use but nothing seems to work. Here is my query: SELECT * FROM name as n1 FULL JOIN aka_name ON n1.id = aka_name.person_i...

MySQL - How do I inner join sorting the joined data

I'm trying to write a report which will join a person, their work, and their hourly wage at the time of work. I cannot seem to figure out the best way to join the person's cost when the date is less than the date of the work. Let's say a person cost $30 per hour at the start of the year then got a $10 raise o Feb 5 and another on Mar 1....

How do I do a left outer join in LINQ?

Can anybody explain in detail how to implement a left outer join in LINQ? ...

MySQL - Join as zero if record Not IN

To explain by example, take two tables, A and B Table A id foo 1 x 2 y 3 z Table B id aid bar 1 3 50 2 1 100 An example join SELECT foo, bar FROM a, b WHERE a.id = b.aid; Garners a result of foo bar z 50 x 100 What I would like to do is get all values of foo and for any instances where there isn't a...

Can someone recommend a good tutorial on MySQL indexes, specifically when used in an order by clause during a join?

I could try to post and explain the exact query I'm trying to run, but I'm going by the old adage of, "give a man a fish and he'll eat for a day, teach a man to fish and he'll eat for the rest of his life." SQL optimization seems to be very query-specific, and even if you could solve this one particular query for me, I'm going to have to...

mySQL Query JOIN in same table

Table structure goes something like this: Table: Purchasers Columns: id | organization | city | state Table: Events Columns: id | purchaser_id My query: SELECT purchasers.*, events.id AS event_id FROM purchasers INNER JOIN events ON events.purchaser_id = purchasers.id WHERE purchasers.id = '$id' What I would like to do, is obvio...

sql sum data from multiple tables

I have 2 tables AP and INV where both have the columns [PROJECT] and [Value]. I want a query to return something like this : PROJECT | SUM_AP | SUM_INV I came up with the code below but it's returning the wrong results ( sum is wrong ). SELECT AP.[PROJECT], SUM(AP.Value) AS SUM_AP, SUM(INV.Value) AS SUM_INV FROM AP INNER JOIN INV ON...

How can I join conditionally in LINQ queries?

If I have two tables; Drivers keyed by DriverId and Trips with foreign keys DriverId and CoDriverId, and I want to find all trips where a driver was either the driver or co-driver I could code this in Transact-SQL as select d.DriverId, t.TripId from Trips t inner join Drivers d on t.DriverId = d.DriverId or t.CoDriverId = d.DriverId ...

ERROR: there is no parameter $1 when creating view

When we try to create a view within a funcion we get ERROR: there is no parameter $1. This is the sample code. Begin CREATE VIEW artikelnr AS SELECT datum, 'uitgifte' as "type", CASE WHEN 'test'='test' THEN 0 END as "aantal ontvangen", aantal as "aantal uitgegeven" FROM uitgifteregel JOIN artikel ON artikel.artikelnr = new.artikelnr J...

Can I expect a performance gain from removing this JOIN?

I have a "items" table with 1 million rows and a "users" table with 20,000 rows. When I select from the "items" table I do a join on the "users" table (items.user_id = user.id), so that I can grab the "username" from the users table. I'm considering adding a username column to the items table and removing the join. Can I expect a decent...

SQL COUNT records in table 2 JOINS away

Using MySQL, I have three tables: projects: ID name 1 "birthday party" 2 "soccer match" 3 "wine tasting evening" 4 "dig out garden" 5 "mountainbiking" 6 "making music" batches: ID projectID templateID when 1 1 1 7 days before 2 1 1 1 day before 3 4 2 2...

SQL query using information from 4 tables (not all directly linked)

I'm developing a simple classroom system, where teachers manage classes and their subjects. I have 2 levels of access in my teachers table, assigned by an integer (1 = admin, 2 = user)... Meaning that the headteacher is the admin :) A teacher (of level 1) can have have many classes and a class can have many teachers (so I have 'Teacher...

SQL: How to join a view with a table?

UPDATED: I am using MySQL statement to create a view: I need to show Editors First Name, Last Name and the City if they shipped more than 50 books. The three tables I have are: create table editors ( ed_id char(11), ed_lname varchar(20), ed_fname varchar(20), ed_pos varchar(12), phone varchar(10), address varchar(30), ...

SQL Join to only the maximum row puzzle

Given the following example data: Users +--------------------------------------------------+ | ID | First Name | Last Name | Network Identifier | +--------------------------------------------------+ | 1 | Billy | O'Neal | bro4 | +----+------------+-----------+--------------------+ | 2 | John | Skeet |...

How do I join these queries?

query1: SELECT category.id, category.name, category.level, category.description, category.cat1, category.cat2, category.cat3, category.cat4, category.pri_color, category.sec_color, category.last_report AS report_id FROM category, reports_category_layout WHERE category.id = reports_category_layout.catID AND reports_category_layout.site_...

max count with joins

I have 3 tables: users: Id Login 1 John 2 Bill 3 Jim computers: Id Name 1 Computer1 2 Computer2 3 Computer3 4 Computer4 5 Computer5 sessions: UserId ComputerId Minutes 1 2 47 2 1 32 1 4 15 2 5 5 1 2 7 1 ...

Hibernate Criteria: Perform JOIN in Subquery/DetachedCriteria

I'm running into an issue with adding JOIN's to a subquery using DetachedCriteria. The code looks roughly like this: Criteria criteria = createCacheableCriteria(ProductLine.class, "productLine"); criteria.add(Expression.eq("productLine.active", "Y")); DetachedCriteria subCriteria = DetachedCriteria.forClass(Model.class, "model"); subCr...

SQL Select table1.columa as table1.columb

I am working on a database join and I want to do the following: Select tabel_one.id, tabel_one.title, tabel_one.content, table_two.value as table_two.key from tabel_one Join table_two ON table_two.id = table_one.id .... The Important part is: table_two.value as table_two.key Is there a way this could w...

Please explain me MySQL Joins in simple language?

Please explain me Joins in simple language? please do not post the weblink as i need how a developer gets it not how the author.. pls understand :) ...

When to use JOINs

It seems to me that there are two scenarios in which to use JOINs: When data would otherwise be duplicated When data from one query would otherwise be used in another query Are these scenarios right? Are there any other scenarios in which to use JOIN? EDIT: I think I've miscommunicated. I understand how a JOIN works, what I'm not s...