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

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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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4answers
888 views

Self Join? Or am I wrong?

We have a table that we use to store customers and items. We need to be able to find customers that have bought one item and have not bought another item: customer item Sally 1 Sally ...
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38 views

Help on MySQL joins

I'm building a system to monitor currency prices. Part of my database structure looks like this: My system is trying to pull the api ticker for each exchange with this query: SELECT distinct ...
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1answer
2k views

Merging tables, but ignoring duplicate columns

I have two tables I want to merge: city1(id, city, state, zip, lat, lon, county) city2(id, city, state) The tables contain overlapping city and state, but not primary keys. I can't figure out how ...
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1k views

Left outer join not returning all rows in a grouping query

I'm trying to query all users to find the price of orders in the last month. I'm doing this on PostgreSQL. Here's a toy database to show my problem: I have a people table and an orders table. I'm ...
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1answer
201 views

SELECT query with DISTINCT on a table-structure for graphs is very slow

I have 2 tables where nodes contains about 60m rows and edges about 500m rows (both growing fast). These two tables represent a directed graph. CREATE TABLE edges ( node_from bigint NOT NULL, ...
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1answer
81 views

How to join by most recent preceding date?

Imagine I have a database with historic price data and a second table with dates Item | Price | Date Customer | Item | date ------------------------- --------------------------- ...
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267 views

Select Information from All Tables [closed]

EER Diagram Question List the customer number, customer name (first and last), order number, order date, employee number, employee name (first and last), product number, product name, and order ...
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1answer
55 views

(How) can I return the most specific row on a join?

I'm trying to work out a query that can parse through a table of prices (and exceptions to those prices) to yield the applicable price for a product, ideally using a join. I'm on PostgreSQL. For ...
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54 views

SQL JOIN excluding duplicate

I'm using PostgreSQL under ubuntu 14.04. I have two tables as below: create table material_base_name ( id bigserial, base_name varchar(50), constraint pk_materials_base_name primary key (id) ); ...
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1answer
60 views

Help with optimising a sql query on two partitioned tables

I have a SQL query that I am running on two very large tables in SQL Server 2012 Enterprise The two tables are ACKs and Logs. Both are partitioned on their time by day column with the appropriate ...
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3answers
455 views

SQL join with multiple columns as FK to same list table

I have a table that has 5 references to a list table for normalization of the first table. So in the table 1 a row looks line other columns..., reference_1, reference_2, reference_3, reference_4, ...
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71 views

MYSQL Tables Join Filtering For Favorites

I am in need of some help figuring out the best way to join separate tables I am using. I am essentially trying to output a list of schools (first table in MYSQL) where one column is an empty star ...
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60 views

Joining a column from another table with InnoDB engine

I'm using MySQL with InnoDB and I want to join the location column from products table into a productStock table. I have this table 'products' mysql> select * from products; ...
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2answers
113 views

Subquery or multiple left joins, or both?

I have two tables, for simplicity table1, with id as Primary key, and a field name, and table2 with the same. Each table has quite a few records, but during a complicated form process, the user is ...
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2answers
81 views

Combine two queries from 1 table, 1 to Many

I have the following queries select o.increment_id, o.customer_id, round(o.base_grand_total * o.base_to_global_rate,2) as revGBP, DATE_FORMAT(o.created_at, '01/%m/%Y') as 'MonthofOrder', from ...
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1answer
960 views

How to optimize a very slow query with joins and group by?

I have this GTFS database : All the ***_id columns are indexed, and there are foreign keys between tables (such as a FK on trips.route_id to routes.route_id). So basically the link between a stop ...
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3answers
3k views

Alternatives for a LEFT OUTER JOIN query

Problem I have a SQL statement with an LEFT OUTER JOIN which works fine on our Microsoft SQL Server. My problem is that i have to be compatible with H2 Database and this one got a bug with OUTER ...
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71 views

How to use join with this query? [closed]

This query is working fine, and giving the right result. In this query all columns are in one table, but now I have made some changes. Now columns named Semester and Major are in different Table ...
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1answer
86 views

SELECT count vs DELETE JOIN. Why/how are they different?

Can someone explain in what way these queries could be different and the results are not the same? > begin; Query OK, 0 rows affected (0.01 sec) >select count(*) from tableA a JOIN tableB ...
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1answer
196 views

Selecting most recent date when dates are stored in another table

Working in a MySQL database, I have tables set up like this: Table song_instances has song_id (int), meeting_instance_id (int) The meeting_instances table has columns meeting_instance_id (int), ...
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2answers
105 views

How are derived table implemented in MySQL

When MySQL makes a derived table as a result of SELECT (SELECT ...) etc or SELECT * FROM a JOIN (SELECT * from B) etc or SELECT * FROM (SELECT ...) Are these derived temporary tables created ...
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1answer
64 views

How to JOIN more than two tables?

Following is the schema of my Tables: Marks_Table (SubjectCode,TypeID,MarksObtd) Subjects_Table (SubjectCode, Subject) Types_Table (TypeID, Type) I want to Select the Marks_Table table with ...
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69 views

Drastic change in query speed when changing from Oracle 9i to ANSI outer join syntax

I am working on simplifying a query originally written for Oracle 9i. In the process I changed the join syntax from the Oracle 9i syntax to ANSI. The names of the tables and columns have been changed ...
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Packet and N-SubPacket Msql query ( same as catgeory and N sub catgeory )

First of i am PHP Developer , and working on huge project alone .i think i have made many mistake in creating table. and below is one of those. I am making packet type system when in my Packet Table ...
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72 views

mysql join not working as expected

i want to select schedule of specific teacher for a given day .... statement should assume that a teacher may teach in elementary and high school here is my statement `select class.name as ...
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3k views

Select all rows with multiple conditions in another table

Here is my simplified database scheme -- ----------------------------------------------------- -- Table `products` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS ...
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66 views

SQLITE table joining with group

MESSAGE TABLE USERS msg_id | msg_to | msg_from | msg_body | msg_date user_id | user_name 1 1 2 hi 22/1/14 ...
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1answer
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Join tables in two databases make query slow? is better to partition db?

I have a table1 in db1 and table2 in db2 on SQL Server 2008 R2. If I make a select query joining both tables, it's really slow to get the results. A simple query like SELECT * FROM db1.dbo.table1 ...
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1k views

Pivoting some row data into columns (SQL Server 2008 R2)

Sorry if this has been answered before but I'm exhausted and on a time line. Maybe I'm just an idiot. I'm designing a data export from One application to import into another. Full-Disclosure: I did ...
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2answers
99 views

JOIN on 3 tables being slow

everyone. Can't figure out what indices are missing or how to rephrase my query. I created about a milllion of test entries in each table to see performance. Query takes about 1.5 seconds which is ...
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1answer
175 views

queries for hierarchical data

This table is a questions and answers CMS and i want to know how data is fetched from these tables. +------+----------+-------+ | id | parentid | type | +------+----------+-------+ | 1 | 0 ...
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366 views

Speed up a MySQL BETWEEN query

SELECT dateToFind FROM table1 INNER JOIN table2 ON dateToFind BETWEEN dateFrom AND dateTo I need to improve the performance of this kind of query. I added BTREE indexes on dateToFind, dateFrom, ...
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Outer Apply vs Left Join Performance

I am Using SQL SERVER 2008 R2 I just came across APPLY in SQL and loved how it solves query problems for so many cases, Many of the tables I was using 2 left join to get the result, I was able to ...
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2answers
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“All joins can be rewritten to sub queries”, is this statement true?

I wonder if there any case that a join can not be converted to a sub-query. BTW: I am not discussing advantages and disadvantage of using sub-query or using join.
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1answer
5k views

CROSS APPLY versus INNER JOIN

I was reading a lot about CROSS APPLY versus INNER JOIN recently. I tried writing some queries and they both work in a similar fashion, the execution plan seems to be same as well. Maybe someone ...
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687 views

left join not working [closed]

CREATE TABLE `table1` ( `id` INT(10) NOT NULL ) ENGINE=InnoDB; CREATE TABLE `table2` ( `id` INT(10) NOT NULL, `value` INT(10) NOT NULL ) ENGINE=InnoDB; INSERT INTO table1 VALUES (1), (2), (3), (4); ...
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2k views

Joins in Update statement in sqlite

CREATE TABLE Table_1 ( Id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL , EmailId VARCHAR ) INSERT INTO Table_1 VALUES (1,'raj@gmail.com'); INSERT INTO Table_1 VALUES (3,'test@gmail.com'); ...
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1answer
110 views

MySQL Join, Force NULL Row

I'm having a bit of trouble figuring out how to do this -- I need to select all rows from table t1, join table t2 -- but include a null row from t2 for each record in t1 (even if rows match in t2). ...
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211 views

PostgreSQL SQL syntax - JOIN and substrings

I have a single table of hostnames and NFS exports, some but not all of which are related. Example entries: HOST VOLUME ----- ---------- host1 vol1 host1 vol2 host1 ...
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MySQL get values from the other table by using inner joins

In mysql I have 3 tables called as ps_product_lang ps_order_detail and ps_image here are the tables sample data === ps_product_lang === CREATE TABLE IF NOT EXISTS `ps_product_lang` ( ...
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1answer
43 views

Query Rows That Have a Following Row That Meets Criteria

Will try to do my best to explain this, as I don't really know how to word this to search for an answer. I'm a constantly learning but still newish SQL user who thus far has been able to solve most ...
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1answer
2k views

SQL Server Multiple JOINS with Table Value Function - query never ends

I have a query with 4 joins using a table value function to get the data and when I execute it the query never ends. Issue Details Table valued function: CREATE FUNCTION [dbo].[GetIndicator] ( ...
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1answer
185 views

If an INNER JOIN in a query returns no rows, do additional INNER JOINS add a significant performance overhead?

If I make a query as follows: SELECT * FROM TableA A INNER JOIN TableB B ON A.AID = B.AID INNER JOIN TableC C ON B.BID = C.BID Does the INNER JOIN with TableC add significantly to the performance ...
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1answer
656 views

Cartesian product of two tables not working as expected in MySQL but fine with SQlitee?

I was practising some sql joins and decided to create a schema online rather than using my local database on sql fiddle. My schema is pretty simple table 1 (5 entries): (emp->{id,name,dep}) table ...
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1answer
71 views

Understanding JOINs and why the syntax works the way it does

Heyo, I'm confused as to how this works: UPDATE original SET price=(SELECT price FROM new WHERE new.id=original.id) WHERE id IN (SELECT id FROM new); What it does is updating an original table ...
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100 views

Merge output of two Queries MYSQL

I have a mysql table with the following schema: +------------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | ...
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1answer
98 views

What column is this alias referring to?

I've read the following code a few times trying to figure out what it is doing. "A right outer join is that which returns the unmatched rows from the right tables with matched rows from the left ...
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1answer
5k views

MySQL: Which join is better between left outer join and inner join

Which join is better peforming if all of them provides the same result? For example, I have a two tables employees(emp_id,name, address, designation, age, sex) and work_log(emp_id,date,hours_wored). ...
2
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1answer
97 views

WHERE attribute having two relation lines in the same SQL

I have a database designed with tree tables: checklist (id, name) tag (id, name) checklist_tag (checklist_id - FK, tag_id - FK) Running this SQL: SELECT cc.id as checklist_id, cc.name as ...