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

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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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Mysql join non-unique columns

I have two tables, want to join them by an non unique column. CREATE TABLE `order_item` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `soi` char(1) DEFAULT NULL, `product` char(4) DEFAULT ...
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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 ...
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1answer
21 views

DB2 LUW: how to influence query planner's choice of join

Suppose I have two tables, A and B. They "share" the same primary key, which is indexed in both tables. Table B also has a timestamp column which is separately indexed. I do a subselect on B using ...
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SQL Update column with data from another table

I am working on complicated problem, but I will simplify it to this problem. I have two tables A [ID, column1, column2, column3] B [ID, column1, column2, column3, column4] and i want to update ...
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1answer
50 views

How to make an union on 2 joined tables without affecting the sum on the column? [closed]

I have the following tables: cant: id CANT_VAL COD_VAL fk_id_chest c1 c2 18059 18.56 R12 1 100 11 18060 11 R10 2 200 22 18061 15 ...
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1answer
40 views

Using group by on several tables with problems [closed]

I have a poorly-designed table in an Oracle database like this: sr: id an_rap 21 2015 rap: id cf 28185 123-123 ch: id fk_id_rap FK_ID_SR 12348 28185 21 dma: ch_id ...
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1answer
23 views

How can I group two joined tables

How can I group (by) two joined tables (in an Oracle database) like this: cant: id CANT_VAL COD_VAL fk_id_chest 18059 18.56 R12 1 18060 11 R10 2 18061 15 ...
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1answer
31 views

How can I group (by) two joined tables [closed]

How can I group (by) two joined tables (in an Oracle database) like this: cant: id CANT_VAL COD_VAL 18059 18.56 R12 18060 11 R10 18061 15 R11 col: FK_ID_COL_DMA ...
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2answers
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Join subquery by year and month

I want to collect data from differed tables grouped by year and month. I'm using subquery for each sub data. Using mysql. SELECT YEAR(td.db_date) AS stat_year, job.total_jobs FROM ...
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1answer
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Trying to get all checkins open during day at specific times

Db structure looks somewhat like this. id, transdate, opentime, closetime 1 2015-11-02 2015-11-02 17:51:00 2015-11-02 18:51:17 2 2015-11-02 2015-11-02 17:58:00 2015-11-02 19:26:52 3 ...
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1answer
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Using inner join to get data from multiple tables [closed]

I have 5 tables: A (a_id, a1, a2) B (b_id, b1, b2, a_id) C (c_id, c1, c2, b_id) D (d_id, d1, b_id) E (e_id, e1, e2, d_id) Here is some information table b have a_id match with table a (a_id). ...
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Why does SemiJoin node receive so bad statistic even after runnning ANALYZE

PosgtreSQL 9.4 I have two tables: CREATE TABLE home_transactions( id serial NOT NULL, transaction_id integer ); CREATE TABLE transactions( id serial NOT NULL, user_id, amount numeric(13,4) NOT NULL ...
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1answer
381 views

SQL80001 - incorrect syntax near ')'

In the below code (that I've inherited), I'm getting the message "SQL80001 - incorrect syntax near ')'", the error being on the third line from the bottom with the + sign. I've looked at THIS SO ...
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1answer
55 views

Why does STRAIGHT_JOIN consume more CPU?

Why does STRAIGHT_JOIN consume more CPU than a regular JOIN? Do you have any idea? When I use STRAIGHT_JOIN on one of my queries, it speeds up the query like from 12 seconds to 3 seconds. However, ...
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limit aggregate function across join

I have a facts table, and each fact has one-or-more distributors in fact_distributors. A distributor is an entity, and for reporting purposes entities are grouped together into an entity_group via ...
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How can I combine join and random choice from one table but 2 conditions?

I want to choose 200 entries randomly from a table However, I have two conditions the first 100 should be white and the other black. How can I join them? One possibility to do is to run following ...
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1answer
72 views

Sum of values for each row

SELECT ratings.programme_id, programme.programme_name, ratings.ratings FROM programme INNER JOIN ratings ON ratings.programme_id = programme.programme_id I have two tables a and b a has id and name ...
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1answer
81 views

MYSQL join on subquery optimization

This is a distilled version of the query that I am trying to run: SELECT * FROM table1 t1 INNER JOIN (SELECT * FROM table2 WHERE foo = 'bar') t2 ON t1.id = t2.id; The above query is incredibly ...
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3answers
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Performance impact of NOT using a foreign key (many dedicated 1:many key-key tables vs non-fk generic key-key table)

We're using a lot of association tables to manage 1:many relationships among a variety of different objects in our system. To illustrate the question, two examples would be: users, events, ...
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1answer
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Adding a second Group By column slows query down

I have the following query: SELECT 'TEXT', 'TYPE', 'DESTINATION', 'HEADLINE', 'COUNTRY_ID', 'COUNTRY_CODE' UNION ALL SELECT Data_1.TEXT, Data_1.TYPE, Data_2.Destination, Data_2.HEADLINE, ...
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Performance inner join vs left join involving parallelism

I have a query which takes about 8 hours to finish. Simplified, the query looks something like this: SELECT [Some attributes, inconsequential] FROM RBM.Financial_Events RFE INNER JOIN ...
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1answer
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Syntax error in UNION ALL [closed]

I have syntax error in UNION ALL line 8.. what is the mistake? I'm using mariadb, (Innodb) SELECT 'Süre Bitiş Tarihi','Tc Kimlik No', 'Kullanıcı Soyadı, Adı','E-posta', 'Telefon','Diğer ...
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Materialized View - vs. New Calculated table for performance [closed]

I have a problem - I'm trying to de-normalize data tables in a data warehouse in preparation for use in the Business Intelligence/ Presentation layer. By denormalize I mean create a series of joins. ...
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1answer
78 views

Improve execution time of query in POSTGRES with multiple joins

I'm having the trouble with the following query due to the growing size of the database ( websites is around a million rows, misspelled goes up to a couple millions ) It can reach up to 165 seconds ...
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2answers
73 views

Improving performance on a join query

I have the following MySQL query that I am attempting to run against a set of tables prepopulated with data: $sql = sprintf(' SELECT video.id, video.name, video.created_at, video.duration, ...
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2answers
160 views

Efficient way to join two tables with one to many relationship

This is interview question asked to me in interview and i was not able to answer. Please help.. What is the most efficient way to join two table with one to many relationship between them
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1answer
55 views

Joining 3 Tables

I have 3 tables as per below: **ATTRIBUTE TABLE** PeopleAttrCODE PersonCODE AttributeCODE Value 1 1 End Date 20151231 2 1 Start Date ...
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1answer
35 views

Update rows in a table with an index column starting from 0 with consecutive numbers

I have a few tables in a Oracle db with some "rule": The INDEX_COLUMN must start from 0 and must be consecutive numbers and the column NRCRT must start from 1 and also consecutive numbers. I've made a ...
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1answer
72 views

How to match column names and values from joining and related tables?

I have the following DB structure: cars: id make features: id name cars_feature: id car_id feature_id value I want to be able to select all cars with all features and return results with ...
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Access (Jet) SQL: DateTime stamps in TableB flanking each DateTime stamp in TableA

First Words You can safely ignore the sections below (and including) JOINs: Starting Off if you just want to take a crack of the code. The background and results just serve as context. Please look at ...
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1answer
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How do I make this Postgres view that performs a join updatable?

I've got two tables, products and subscriptions: CREATE TABLE products ( id bigint NOT NULL, title character varying(75), description text, manufacturer_id bigint, created_at ...
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Joining one table with multiple tables for aggregate functions possible?

I am trying to get this seemingly simple looking query to work : SELECT c.id, c.name, count(chc.id) as contacts_count, count(cha.id) as addresses_count FROM (customers c LEFT JOIN ...
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1answer
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How do I get only those values that has related elements from other table?

I have three tables for a social network: companies, users and countries. Users belong to Companies and Companies have a Country. All tables have their own id column. Table users has a company_id FK ...
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2answers
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Is there any way to force MySQL use Hash Join instead of Nested Loop Join?

According to the document MySQL Explain Output format, MySQL resolves all joins using a nested-loop join method. Is there any way to force MySQL to use a hash join?
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Whats the difference between the following queries? Getting the top 3 salaries for different department

I am practicing SQL and came across this issue. I am trying to find the top 3 salaries for each department. The table structure is basic with one employee table with columns ...
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1answer
78 views

Receiving duplicate results in one condition of JOINED query

I always end up here when Googling for solutions, so I thought I'd cut out the middleman since I'm unable to fix this via searching/forums. It's my first time posting, so please forgive any faux pas ...
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2answers
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sql problem with multiple linked tables

I have an Oracle db and the following tables: raportor: id id_pct_lucru 58382 327342 ses_rap id an status 1 2012 I 21 2013 I 41 2014 D ch_trat id fk_id_raportor ...
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1answer
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Is it possible to JOIN to a Primary database from a Replication instance?

I have a database on a Replication server that doesn't exist on the Primary server. There are stored procedures on the Replication server's DB that join to tables in other databases on the ...
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2answers
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Help finding join without predicate

Much like a related question by swasheck, I have a query that historically has suffered from performance problems. I was looking through the query plan on SSMS and noticed a Nested Loops (Inner Join) ...
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1answer
27 views

what better way to multiple ON conditions

I've got a table called Customers. And a table Users. (MySQL 5.3) Customers: customerID|customerName|accountManagerID|attendantID 123 |Google |456 |789 124 |Apple ...
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2answers
3k views

how to join table from different database with different Users of database?

I have Two database called. Database1: host: 127.0.0.1 user: root1 pass: root1 dbname: db1 Table 1: Category ID INT(11) Primary Key Name VARCHAR(255) Database2: host: 127.0.0.2 ...
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1answer
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Improving SQL Query joins performance

We have been using SQL Server 2014 for our project as a backend source. We have been performing various joins on the tables. We came across a question in one to many and many to one relationship in ...
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Is it correct, order of where clause doesn't matter when it is used with join?

I have question on execution of queries in which join is used with where clauses. I read this question on join with where conditions. I tried options like disabling rules and checked actual query ...
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88 views

Count for many-to-many relationship

I have the following tables: surveys properties owners_properties owners ---+------------ ---------- ------------+--------- ------ id | property_id id ...
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Reason of poor performance of ANSI joins in Oracle 9i

Please before flagging as duplicate, read the last paragraphs. In an Oracle 9i database this query runs in 0.18 seconds: select count(*) from dba_synonyms s,dba_objects t where ...
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59 views

SQL Server - Update using Join in Merge

Scenario : I need to update values in a table by joining it with another temp table. But I am using a Merge statement to check various scenarios and update the values in the table when the condition ...
0
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1answer
23 views

SQL query with multiple many-to-one joins [closed]

I want to select a count of all surveys where the survey.property.address.city == "Garrison". I have the following tables (stripped for your convenience): surveys properties ...
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1answer
34 views

Join MySQL Lookup tables

I have the following MySQL tables: games genres game_genres Games can have many genres (action, fighting, horror), so they're in a lookup table with game_id and genre_id. When I pull in my list of ...