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

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4
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1answer
194 views

Select multiple columns from subquery - Connect by

I have a table which manages folder structure. Hence it has a parent-child relationship. We trigger a query to sum all documents in the complete heirarchy: SELECT folder_name name, ...
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1answer
30 views

Using a join operation with conditionals

I have two tables that I'm working with in my database. I am using SQL Server 2014. One is 'versions', that contains version_id, version_number, start_date, end_date and server_id. The other is '...
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1answer
54 views

MySQL Query fix and speed up

I'm newish to MySQL and a lot of my query is pieced together from this site and trial and error, so any help is appreciated. If I left out anything, or more detail is needed, I will be happy to give ...
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1answer
29 views

Multiple references to another table, but I don't know how many

I have two tables in a database, folowwing this model: scientists : id (int) | name (varchar) | surname (varchar) | publications (int) publications : id (int) | fulltext (varchar) I would like to ...
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0answers
36 views

How to avoid row locks on both tables joined in an update?

I have little knowledge about MySQL internals, but I'm experiencing that in a query like: UPDATE t1 JOIN t2 ON t1.id = t2.id SET t1.a = x, t1.b = y, [, ...] WHERE [ ... ] rows from both t1 and ...
4
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2answers
382 views

Outer self join filters vs subqueries

I have a table storing information about tickets. There is one record when ticket is sold and another when ticket is used. There is a column called TransType which is set to either 'sold' or 'used' ...
2
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1answer
51 views

Can I avoid a join for my select procedures?

Here is a really simple example of a select procedure I'd like to create, although it's only partly done (it's pretty self-explanatory): delimiter // CREATE PROCEDURE mysql.selectTables (_first_name ...
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1answer
27 views

How to return null values from a joined table if the matching row is missing?

Here is what I need to achieve: person_id last_name first_name region_id region name 1 barnum phineas 1 maricopa 2 loman ...
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1answer
25 views

Query to sort through history table

I have the above tables and want a query that will give the results as above. Basically I have a table of history where I want to display single row by adding two column that show prior Group from ...
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0answers
31 views

Groupwise max then join

I have a votes table that has many subitems. I have a subitems action table that records what action was performed by which user on which group, on which subitem, on which vote Users can either cast/...
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3answers
67 views

How should INNER JOIN query look?

I am trying to fetch some records using INNER JOIN. The problem is that I am not sure what's the best (recommended) way of doing it. What "pros" and "cons" have the queries shown below? All of them ...
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1answer
37 views

Help on joining 3 tables Oracle XE 11g

I am trying to return the first name, surname, subject and mark from the following tables: SQL> desc students; Name Null? Type ------------------------ -------- -------------...
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11 views

Find missing associations in many to many relationship [duplicate]

I have client and category tables with a many to many relationship via client_category_association. table: client id name 1 ek 2 do table: category id name 1 un 2 dos 3 tres table: ...
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1answer
28 views

Join second table based on third table with conditions

I"m using Doctrine for a website that has 3 tables to connect together. In simplest terms, they look like this Contractor - id - name ContractorJob - id - contractor_id - job_id - status Job - id - ...
0
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2answers
51 views

need help joining two tables with a having count clause

I am a network guy so I apologize for this.... I have two tables I need to join and pull names out of. pt_basic has the patient names and codes I need, ptc_diagnosis has their diagnosis. I need to ...
3
votes
1answer
89 views

DELETE rows which are not referenced in other table

I have two tables in a PostgreSQL 9.3 database: Table link_reply has a foreign key named which_group pointing to table link_group. I want to delete all rows from link_group where no related row in ...
3
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1answer
24 views

How does Hash Join works with relational operators other than equality operator?

I have been reading about Hash Join and how does it work in physical level. However, there is some thing that I don't understand (because of my lack of knowledge). This is the algorithm of Hash Join ...
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1answer
43 views

Galera MariaDB not joining with IST

Until now, I have a single MariaDB 10.1 node running as Galera Cluster. So, now I want to join the next one. systemctl start mysql initiates the snapshot state transfer (which takes about 10 hours ...
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1answer
61 views

Select column values linked to exact set of values in another column

Given the below chats_users table in Postgres 9.5, with integer columns chat_id and user_id, I want to find the chat_id associated with an exact set of user_ids, for example: user_id IN (1, 3) => ...
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1answer
66 views

Same query plan, different data set, very different query duration SQL Server 2012

This may be a terrible question, because I'm not sure how information I can include to help. We have data segregated by customer. One customer apparently has higher volume of data. The same query ran ...
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0answers
48 views

Inner join on array columns from 3 tables

I have 2 tables that are related between them using integer data which is stored in arrays. Data table telemetria_data.historico_354677050164513 CREATE TABLE historico_354677050164513 ( imei ...
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1answer
21 views

MAX and MIN for each car model

I have a problem with a query. I have a db with car and their spec, every model has a different car related to that model with its price. I want to create a query that gives me the min and max price ...
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2answers
68 views

How to avoid full table scan when using OR operator on an Index

Essentially, I want to get intersection between 2 tables based on matching IDs with the option of wildcard '*' to return all IDs: Select * from A a inner join B b on b.id = a.id or b.id = '*' ...
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1answer
45 views

Creating a view with a Left Outer Join and Where Condition

Let's say I have a User Table and a User Record table which lists Data Sources associated with that User. I want to create a (Sql Server) View that lists all the contents of a User, and an optional ...
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1answer
27 views

Teradata Join Syntax

I'm having a hard time doing what I want to do here, as SQL (and Teradata SQL on top of that) is not my main forte. I have two queries that I want to join together. I want everything that returns ...
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41 views

Query the database for particular value in a column

I have 2 tables which look like this: Table_1: Contains Item Details ------------------------------------------------------ Item_ID | Location | Arrival_Date | Postage_Date | ... -------------------...
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1answer
36 views

Select and Insert for all data - Need help querying [closed]

At a first glance, this is my query INSERT INTO T2 SELECT T1.*, T3.DATETIME, T3.STATEID FROM T1 WHERE T3.DATETIME BETWEEN '01-NOV-15' AND SYSDATE LEFT OUTER JOIN T3 ON (T1....
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1answer
33 views

Get a specific number of rows from parent table?

I have a parent table, foo, and a child table, bar, in a mySQL database. Each row in foo may have zero or more child records in bar. I want to get exactly 15 rows from the parent table, and all ...
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1answer
36 views

Query using joins [duplicate]

I have the table Vendors (VendorID PK, VendorName, VendorContactFName ,.....) I want to find out the VendorName and VendorContactFName for those Vendors whose Contact First Name is different from The ...
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2answers
99 views

how do I use a value from the select in a joined subquery?

I'm trying to avoid a stored procedure or bringing it into code but they may be my only alternatives. Here's my sql. Does anyone know any SQL voodoo that could make this happen without a stored ...
0
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3answers
106 views

Optimise MySQL SELECT with LEFT JOIN subquery

I have a query which combines a LEFT JOIN and subquery. The dataset is quite big and the time to execute the statement is over 70 seconds. SELECT s.siblings, l.id FROM `list` l ...
0
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1answer
58 views

How to group joined tables by aggregate function, specifically by average group-name type?

I'm trying to build a query selecting two columns (category types) from one table JOINED to another table-column displaying average grades as percentage number-types; here is my first attempt: SELECT ...
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1answer
26 views

right join leaving one row from right table

I am using MariaDB,in my sample database I am having two tables department and emp. I want to display all the department having less than 50 employees. In this case it should display all the ...
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1answer
60 views

How Can Get Random 2 rows FROM EACH GROUP FROM JOINED TABLE

EXAMPLE Table Dept: dept_id dept_name dept_status --------------------------------------- 1 Sales 1 2 Develpment 1 3 HR 1 ...
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2answers
69 views

How to prevent PostgreSQL from rewriting OUTER JOIN queries?

My query is: SELECT Acol1, Acol2, Bcol1, Bcol2, Ccol1, Ccol2 FROM tableA LEFT JOIN (tableB FULL JOIN tableC ON (Bcol1 = Ccol1)) ON (Acol1 = Bcol1) EXPLAIN ANALYZE gives ...
0
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1answer
26 views

Subquery uses ungrouped column “s.student_id” from outer query

I have the following tables: 1 teacher can have 1 or more students 1 student can have 1 or more homeworks I would like to know in a list of teachers, for each teacher if it has any student with ...
2
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1answer
51 views

SQLite JOIN … USING - rowid works, but then it doesn't

This works. SELECT * FROM Demographics JOIN MeasuresofBirthAndDeath ON Demographics.rowid = MeasuresofBirthAndDeath.rowid; This does not. SELECT * FROM Demographics JOIN MeasuresofBirthandDeath ...
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1answer
52 views

Join a calendar table and a transaction table

The database (DB2) in my company contain two table : Warehouse_transaction contain item_id, transaction_qty (negative or positive value), transaction_date ; Calendar contain all days between 2012 ...
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2answers
31 views

MySQL Union not showing 2nd query result set

I am doing a union of 2 queries and trying to fetch data on two different columns, however the union is not fetching the value from 2nd result set. Can you please guide me on this. select * From ...
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1answer
59 views

How to mount a query to join by searching by last date

I have the following tables: TB_PRODUCTS ID COD_PROD Name =============================================== 1 100 Video monitor 2 101 Keyboard 3 102 Mouse ...
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2answers
47 views

An aggregate may not appear in the WHERE clause

I'm attempting to execute the following query to return a data set where the Updated Date is the most recent. I'm thinking my joins are causing the issue, but I'm not sure, and have not made any ...
2
votes
1answer
24 views

ON clause of JOIN specific syntax?

I've been a bit curious about the syntax of the JOIN operation, especifically the ON clause where we set the condition. Let's say we are performing a join on an existing table and a table we have just ...
1
vote
1answer
45 views

Count instances of value from one column in another column located in another table

Let's say I have the following tables : Table 1 task | date 100 | 2016-01-01 101 | 2016-01-01 103 | 2016-01-01 Table 2 task2 | date 113 | 2016-01-01 113 | 2016-01-01 103 | 2016-01-01 ...
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2answers
113 views

Removing duplicate rows with two or more left join tables

With a query like this SELECT a.id, a.name, COALESCE( json_agg(b.*), '[]'::json ), COALESCE( json_agg(c.*), '[]'::json ), FROM a LEFT JOIN b ON a.id = b.a_id LEFT JOIN c ON a.id = ...
0
votes
0answers
24 views

Is joining two tables from the same DB faster than in separate DBs? [duplicate]

Would a query / view for joining two tables that reside in the same DB perform faster than one table from each DB in the same instance? I'm using SQL Server 2008 R2 and it's a simple inner join.
2
votes
2answers
56 views

Cross-product between table column and input values

I seem to be unable to write an SQL query, which computes the cross-product between a table column and a set of given input values. Something along the lines of: WITH {1,2} as Input Select * From ...
4
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1answer
93 views

Table Joined To Itself Appears Inefficient

My ultimate goal is to compare two rows (only two will exist) and for a specific type and determine if its rows values are greater than the other rows type values. The result I came up with seems to ...
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1answer
53 views

MySQL Query on bad designed table with multiple Selfjoins

i have to create a report out of a bad designed database (I cannot change) It saves different Formulars into a form_values table ---+-------+-----------+------- id | value | form_item | entry ---+--...
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votes
4answers
453 views

Query to select max value on join

I have a table of Users: |Username|UserType|Points| |John |A |250 | |Mary |A |150 | |Anna |B |600 | and Levels |UserType|MinPoints|Level | |A |100 |...
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1answer
37 views

How to select rows based on other tables - MySql

I have tables like this: CheckTable (id) (user_id) [0] [403] UserTable (id) (username) [403] [hello] I want to select only the rows from the UserTable that do not have the user id row in the ...