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

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Question Regarding Full outer join and excluding null values from tables [on hold]

How to remove null value after joining 3 tables using full outer join?
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Why are correlated subqueries sometimes faster than joins in Postgres?

This relates to the dataset described in Postgres is performing sequential scan instead of index scan I've started working on adapting the import logic to work with a more normalised schema – no ...
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46 views

MySQL query too long to execute

I have one query that work pretty well: SELECT [MANY THINGS] FROM vehicule v0_ FORCE INDEX (PRIMARY) INNER JOIN categorie_vehicule c1_ ON v0_.idCategorieVehicule = c1_.idCategorieVehicule INNER ...
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aggregate on join latest value

This is a problem I often get stuck in and I hope there is a solution. Let's build an example: Table products: product_id, product_name Table Prices: product_id, valid_since, Price Lets say I ...
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PostgreSQL - Simple column binding

I have many tables of the same length (number of rows) that were previously ordered by some columns as they were being written on disk. My SELECT is of the form: SELECT t1.id, t1.value, t2.value, ...
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PostgreSQL seems to create inefficient plans in simple conditional joins

Consider these two queries: SELECT t1.id, * FROM t1 INNER JOIN t2 ON t1.id = t2.id where t1.id > -9223372036513411363; And: SELECT t1.id, * FROM t1 INNER JOIN t2 ON ...
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INNER JOIN for 3 tables [duplicate]

I am doing a small course in SQL during my academic degree, I am very new with this material. I saw Inner joinning 3 tables on StackOverflow, I tried to do INNER JOIN between my three tables, the ...
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40 views

Left Join Not returning rows when date is in range of longer than 1 day

How do I left join Table A and B? SELECT dev_hour.hour,rtdogs.delivery_date,rtdogs.delivery_hour,rtdogs.total_offer FROM ( SELECT hour FROM ( SELECT * FROM delivery_hour ) xx ...
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Most Recent order from multi join query

Here's the CTE version of the query, but it is returning multiple rows for the same customer. Not just the row containing the most recent open order date: with LatestOPenOrderDate_CTE AS ( Select ...
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1answer
61 views

Subquery can't find column from superquery's join

I'm running into some trouble with SQL: Basically I'm trying to get a result set back that contains a sum of ALL questions asked to employees (grouped by company) and also add the "onetime_items" ...
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34 views

Joining 4 tables of which one is unrelated

I have 4 tables as follows. I want to find a wholesum resultset, limited to 25 records, in the following way: Users from Table1 based on a condition And those Users should not be in Table2 [Non ...
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Get records with specific group name from table A and see if any exist in table B, if it does then add matching records in Table B to group

Let me start off by saying I am not a DB admin or a DB pro, I work with SQL as a php developer but that's about it. So I hope I can explain this properly and I hope one of you DB guys/gals can help. ...
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Fetch items where related rows has different values

I have table in MySQL called attributes, and other table, attribute_values, one attribute can have multiple values, values identified by context attribute and has value_c attribute wich contain value. ...
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43 views

MySQL FULL JOIN on same table

I have a table like this: And I want to get something like: fecha siguiendo seguidores 2016-01-02 430 1430 2016-01-03 450 NULL 2016-01-04 NULL 5000 ...
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1answer
43 views

Combining GROUP BY and JOIN

This seems like a really simple request, but I can't find the answer. I'll admit that I only have a very limited understanding of JOINs, so it could just be that I just don't fully understand the ...
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Natural join question, I have the answer, but I don't know why it's correct. Help?

So I have a relatively simple database schema. I'm not sure why the where clause in the answer magically makes the dept_name duplication problem go away. I'm new to all this and I'm sure the ...
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1answer
54 views

How do I join information schema to the table's data?

I need to join a table using it's column name from the INFORMATION SCHEMA. Is this possible? I actually found another way to work around it. I am using Innodb. For the structure it's kind of ...
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39 views

Join table into different columns

I have two tables (simplified). table1: - id (serial) table2: - table1_id (integer) - value (text) - type (integer) I want to join these two tables, but depending on the type, I want ...
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60 views

Perform join on multiple tables

I have three tables right now in a postgres DB: Artists ID Name Shows ID Date Venue Price Is_sold Ages Time Multi_day Pit Artists_shows ID Show_id ...
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38 views

Get rows with minimum value

I have tables company: company_id | - - - - - - - - - - - - - - 1 | 2 | employee: employee_id | - - - - - - - - - - - - 1 ...
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Union Query format in mysql

I am training in MySQL. I have database called ships. My goal is => For each class, define the number of ships of this class that were sunk in battles. Result set: class, number of sunked ships. Here ...
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1answer
63 views

NOT IN (together with join) query

I have two tables : Part, OrderLine: Part (PartNum PK, PartDesc, Price) OrderLine (OrderNum PK, PartNum PK, QtyOrdered) And I want to find out the parts that were not ordered. I think I have a ...
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Multiple WHERE conditions on same column =val1 but doesnt=val2 or val3

I am trying to filter a table which has NON-UNIQUE transaction id's, joined to a products table on 1 common column. The filter needs to be as follows: equal to :group1 AND NOT equal to :group2 AND ...
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51 views

Inner Joins between Subsets of the Same Table

All, I am trying to figure out the syntax for doing joins between subsets of the same table. I have: Employee ( EmpId PK , EmpFirst, EmpLast, EmpMid, DateHired, SSN, DateBirth, Gender, PhoneNum, ...
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Postgresql join removal

I just watched the very interesting video from Rob Farley "Designing for simplification" and I was wondering if the 4 rules given in the video for join removal also hold on PostgreSQL. If a view is ...
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Select another row if NULL

In a MySQL database I have these tables: Table 1: News news_id int (PK) category int (FK) rating tinyint Table 2: News Detail news_detail_id int (PK) news_id int (FK) language_code char ...
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72 views

How to optimise multiple joins with OR?

I need to extract some statistical information form drupal database tables. The problem with drupal is that it splits it's data for entities across multiple tables and getting simple information from ...
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Can we do a Join on SQL tables on M:N relationship?

hope this is not too dumb/simple. I have been practicing joins recently and I have never seen a join done between tables T1, T2 that are in an M:N (Many-Many) relationship. Instead, joins are made ...
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1answer
64 views

Join query returning 0 rows - impossible where

My query is performed from a php web request using a PDO prepared statement. My desired output is to list the top 10 brands which have the same transaction id as the 'selected' brand :brand by order ...
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1answer
112 views

Hash Join vs Hash Semi Join

PostgreSQL 9.2 I'm trying to understand the difference between Hash Semi Join and just Hash Join. Here're two queries: I EXPLAIN ANALYZE SELECT * FROM orders WHERE customerid IN (SELECT customerid ...
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54 views

Selecting Only One Record with Most Recent Date Using Table Join

I have a list of 463 CARRIER_CD. I am attempting to retrieve the most current BILL_DT for each of the 463 CARRIER_CD. I have uploaded the 463 unique CARRIER_CD to a database named edw_sbx_bt the ...
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I have following two MySQL queries and i want to execute it inside one procedure

Following query returns 10 rows of recipe id's i wants to pass first query's output which is of 10 rows to the second query and display the output of both the queries inside a procedure. Query 1: ...
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UNION or SELF JOIN?

I have a table to hold parent and child posts together. +------+----------------+--------------+-------------+------------+ | p_id | parent_post_id | child_status | post_status | post_title | ...
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Join on multiple columns with OR

I have a table of 1 million record to join another table with 100000 records. However, there are 5 potential keys (lets assume Account Number, email address, membership number, alternative email, and ...
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How to use COUNT() properly with a 3 table join

I have a database where I have driver details, their assigned routes and their stop locations. For each driver on the database I need to find the location (or locations, as it could be more than one) ...
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SQL queries to only show most recent purchase records for individual food items

I'm working with a food purchasing / invoice system in MS Access 2013 and am trying to create an SQL query that will return the most recent purchase price for each individual food item. Here is a ...
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Schema of equijoin in relational algebra

Why does equijoin return a schema consisting of all attributes from both relations (including intersection) when equality between them have already been established? That is, we know that for any ...
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1answer
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Cumulative data and dates - my joins aren't working

So I want to get cumulative data, for every day since a start date until an end date (or today). I have constructed a query that will get the data from a table, but for some reason, some dates are ...
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32 views

Join query with closest date in “ON” clause

I need to make an OUTER JOIN on two tables, based on 2 columns, first id an INTEGER id, which is pretty straightforward to use in the query, but the second one is a DATETIME, which doesn't actually ...
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Join query with different column types in “on” part

In need to make a JOIN on 2 tables based on columns which have different column types. On table A, I have a DATETIME field and, on table B, I have a DATE and a TIME field, which combined would match ...
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Return 2 columns from MySQL subquery?

I'm new in MySQL programing and I have one problem. I created this query: SELECT *, topics.createdate AS TopicCreateDate, (SELECT (SELECT username FROM users ...
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1answer
30 views

Efficiently perform multiple similar updates

I'm trying to extend some existing SQL (SQL Server) that builds a table of all items to act on using a number of queries. Some of these are very similar and costly, and I was hoping to get some advice ...
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1answer
202 views

SELECT values with a condition and JOIN

I am not sure that is a "SELECT/JOIN" problem but I really don't know how to formulate the question. Perhaps you could suggest a better title I have a table (table-a) with a list of items, I Want to ...
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71 views

MySQL optimizer won't use my index

With the following query: SELECT * FROM geoname LEFT JOIN alternatename ON geoname.geonameid = alternatename.geonameid AND alternatename.isPreferredName = 1 AND ...
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WHERE on SQL with JOIN on large tables

We have a set of large tables (millions of records) on a MySQL DB, having schema like so (simplified): T1: id, uid, rid, text1, text2, int1, int2, ... T2: id, rid, tag_id, created_at T3: id, ...
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Mysql FULLTEXT index not used in Many to Many table join search

I've got a set of data in the Books table, with BookID as the primary key. I've also got Subject and Location tables, each of which is joined to the primary Books table with a Many to Many table. ...
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SQL Query help: co-workers and employees from one query

I have two tables defining users and user employments. The user table looks like this: CREATE TABLE `user` ( `id` int(11) NOT NULL AUTO_INCREMENT, `username` varchar(255) COLLATE utf8_unicode_ci ...
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How can I select records which are between 2 dates based on a date in a field in PostgresSQL?

I have two tables: 1 with an Unique ID with the first time they visited (in date format) and a historical addresses table with the same Unique ID, a start field (date field), an end field (date ...
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Is it possible to stack similar columns from a subquery and join the other unique columns in one query?

I am fairly new to the sql world and have been struggling with a query. I have two subqueries that are generating tables with two columns. The first table is part # and model_countH. The second table ...
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Is it better to filter a small set of row with a BOOL or through a JOIN?

Let's say that I have a simple Books table: Books ----- id name description ... It's a pretty small table, at the moment with 60 records and it can grows, but slowly. On a webpage I want to show ...