An SQL join clause combines records from two or more tables or views.

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1answer
278 views

Visually create a join using PHPMyAdmin

I recently started using SQL Server 2008 express and it has a really nice joins interface, whereby you can visually create a join. Is this possible on PHPMyAdmin?
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2answers
628 views

Right Full Outer Join Query

I came across 1 query which is Select * from R Natural Outer Join S Where R=(A,B) has tuples {(1,2),(1,2),(3,4)} and S=(B,C) has tuples {(2,5),(2,5),(4,6),(7,10)}. To implement this I created 2 ...
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1answer
4k views

Using multiple PIVOTs JOINs and GROUP BYs for advanced report generation

I've developed a timesheet recording system, that allows users to record: A Period of time (9:00 to 12:00) What they did during that time (DutyActivity: 1 hour report writing, 2 hours training) ...
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1answer
282 views

Postgres planer JOIN removal

I have two tables, one contains a lot of rarely update data, and one contains a little of frequently update data. Every record in second table has corresponding record in the first, like following: ...
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3answers
1k views

Grouping results to get unique rows after multiple joins

this is my first question on dba.stackexchange, hopefully it will be worth it. I am usually a bit more active on Stackoverflow as I am a developer. disclaimer : I don't have full control over the db ...
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1answer
328 views

Simple select statement not returning correct data

I am trying to return data, where I want the item name (items.name), vendor name (vendors.name), url of the price (prices.url), and the price (prices.price) from 3 different tables (items,vendors and ...
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2answers
3k views

SQL Server Join/where processing order

After reading Slow SQL query, not sure how to optimize, it got me thinking about the general performance of queries. Surely, we need the results of the first table (when other tables are joined) to be ...
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6answers
13k views

Is it possible to mysqldump a subset of a database required to reproduce a query?

Background I would like to provide the subset of my database required to reproduce a select query. My goal is to make my computational workflow reproducible (as in reproducible research). Question ...
6
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1answer
585 views

Why can't we perform joins in a distributed database like Bigtable?

From this answer to What database does Google use?, BigTable is not a relational database. It does not support joins nor does it support rich SQL-like queries. Is this obvious? I do not ...
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3answers
2k views

Column name naming conventions and best practices

I would like some expert opinion on best practices when it comes to column naming. The background is that according to Wikipedia, the following syntax, SELECT ... FROM Employees JOIN Timesheets ...
3
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2answers
335 views

How do I calculate working business minutes?

I'm working on business inteligence reports and one of my task is to create reports for time tracking. I have to report on business minutes (10 hours per day) within business week (monday to ...
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3answers
2k views

Optimizing query using view on EAV structure

An application is writing into a database that follows an EAV structure, similar to this: CREATE TABLE item ( id INTEGER PRIMARY KEY, description TEXT ); CREATE TABLE item_attr ( item ...
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2answers
5k views

What is more efficient, a where clause or a join with million plus row tables?

We run a website that has 250MM rows in one table and in another table that we join it to for most queries has just under 15MM rows. Sample structures: MasterTable (Id, UserId, Created, Updated...) ...
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1answer
453 views

SQL Server: join two tables with “valid-to” dates

I have two tables like so: T1_Key, T1_Data, T1_ValidUntil 1 A 2000-01-01 1 B 2000-06-30 2 C 2005-05-31 3 D 2004-12-31 3 E ...
2
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1answer
513 views

SQL Return Count of Answers with 0's for Choices from another table

My question went dead after one unhelpful answer on SO here I need this to be optimized because it will be called often. It is going into a stored procedure. I am given @slide (tblILDSlide.id) and ...
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3answers
119 views

Can I automate the “on” statement from MySQL queries?

Background In the process of QA/QC, I am writing lots of queries with multiple joins. I am using MySQL. I would like to know how (if) I can simplify join statements, e.g. by setting default fields ...
4
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3answers
2k views

Query to normalize table/combine row text

I have a table (call it oldTable) with columns like so: ID (int),Rank (int),TextLineNumber (int),SomeText (varchar) The primarykey is multi-part: ID+Rank+TextLineNumber. I'm trying to ...
6
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5answers
18k views

Matching single column against multiple values without self-joining table in MySQL

We have a table that we use to store answers to questions. We need to be able to find users that have certain answers to particular questions. So, if our table consists of the following data: user_id ...
7
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1answer
198 views

Are relations slower than a big, inefficient table?

I've been asked in my job to violate the first normal form (repeating groups across columns, using empty / null values) several times, "for the sake of computer processing power". In a nutshell, a ...
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3answers
1k views

How do I join two tables on two different instances of DB2?

There are two instances of DB2 running on the same machine. One has a table aliased to the a table in the other one. Is there a way to do this in DB2 or does it have to be done via an external tool? ...
13
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2answers
897 views

Peculiar Oracle outer join syntax case

I have seen the following in a query that was supposed to be ported from Oracle outer join syntax to SQL standard outer join syntax: SELECT ... FROM A, B, C, D, E WHERE A.A_ID = B.A_ID AND B.B_ID = ...
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3answers
194 views

Are there any database engines which will intuit the join condition based on the existing foreign keys?

It seems strange to me that, when I've defined a foreign key, the engine cannot use this information to automatically figure out the correct JOIN expressions, but instead requires me to re-type the ...
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8answers
19k views

What is the difference between an INNER JOIN and an OUTER JOIN ?

I am new to SQL and wanted to know what is the difference between those two JOIN types? SELECT * FROM user u INNER JOIN telephone t ON t.user_id = u.id SELECT * FROM user u LEFT OUTER JOIN ...
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3answers
254 views

What does the output of a JOIN statement look like?

I've been wanting to use joins for a while, but I'm having trouble visualizing the output so I know how to put it to use. Let's say I have 2 tables: CREATE TABLE Cities ( id INT UNSIGNED PRIMARY ...