A core SQL statement, SELECT retrieves data from one or more tables or other sources of row set data such as views or table-valued functions.

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How to use OR in query with priority?

In a simple query like SELECT * FROM table WHERE id='x' OR id='y' How to give a priority to get only one of the WHERE clauses? I mean getting rows with id='x'. Only if there is no row, get row ...
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1answer
12k views

How do I select items from a table where a single column must contain two (or more) values?

I have a MySQL database table that references different words and their locations in documents. I want to return the IDs of documents that contain all of the words. Here is an example table. docid ...
2
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1answer
114 views

How to select nodes where all children is satisfied?

I have a tree structure of light bulbs. I want to turn on all the light bulbs starting from the leafs of the tree. A light bulb cannot be turned on unless all its immediate children are turned on. ...
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1answer
707 views

How to add additional tables/fields into a query with multiple inner joins?

Given this query (many thanks to RolandoMySQLDBA from question Select records that do not have associations outside a certain list), how do I add other fields from other tables into my result? SELECT ...
2
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1answer
187 views

Search within same ID across several rows

My table has the following structure: +----+---------+------------+-------------+ | id | word_id | meaning_id | sentence_id | +----+---------+------------+-------------+ | 1 | 1 | 15333 | ...
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1answer
95 views

JOIN 2 tables, and query data from them 3 times

Basically I have 2 tables: post_meta and posts. post_meta has a post_id, key and value: post_id key value 6343 make Chevy 6343 model Volt 6794 make Chevy 6794 model ...
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2answers
118 views

HELP with SQL WHERE syntax

I have to pull out a range of entries of a database, all based around two pieces of data. In itself thats fine. An example of the data is: Record ID Tags 1 1423 Day, Sun, Warm 2 ...
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1answer
424 views

Select consecutive number of rows starting from some number

What I need is to select 100 consecutive rows from a table, starting at some defined point without ordering data. As far as I can observe, inserted data to a table is stored in no order but is ...
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1answer
4k views

How to COUNT number of rows with LIMIT?

I want to catch X rows, thus, I set LIMIT X; but how can I simultaneously count the total number of rows too? Currently, I use two separate queries to do so as SELECT COUNT(*) FROM col WHERE CLAUSE ...
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1answer
5k views

Oracle error “too many values”, must be solved with nested SELECTs

I have hit upon a "too many values" error in Oracle, when working with some intricate nested SELECTs. A simplified description of my problem, on a toy problem describing the hierarchy in a company. ...
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1answer
30 views

How to Choose Between VALUES and SELECT for INSERT?

This answer raised the question for me how to choose between VALUES and SELECT in such a function . Using PostgreSQL 9.4.3 on x86_64-unknown-linux-gnu, compiled by gcc (Debian 4.9.2-10) 4.9.2, 64-bit: ...
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1answer
32 views

I want to select all records for those persons who have one or more entries that equals zero dues

DUES_TABLE ID LNAME FNAME DUES DATE 3456 Smith Bob 12.50 2014-10-01 3456 Smith Bob 0.00 2014-11-01 3456 Smith Bob 12.50 2014-12-01 9450 Jones ...
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1answer
273 views

MySQL - Get Minimum Value, Data From Multiple Tables

Good evening all, first post on the DBA forums. I am having real issues working out how to accomplish a seemingly simple task within MySQL as a model for PHP code later on. I am not exactly a MySQL ...
2
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1answer
110 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), ...
2
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1answer
232 views

PostgreSQL WHERE clause with two OR'ed conditions, priority to first

I'm storing user data (username, email, password hash) in PostgreSQL, and I can only enforce uniqueness on username. I'd like to let users provide either their username or their email when they login. ...
2
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1answer
161 views

Select query - group by and sub group by

CREATE TABLE [dbo].[temptable] ( [Id] INT NOT NULL PRIMARY KEY IDENTITY, [uid] INT NOT NULL, [pid] INT NOT NULL, [event] INT NOT NULL, [timeStamp] DateTime NOT NULL ) I want ...
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2answers
497 views

Why does MySQL fail to use an index effectively when LIMIT offset is large?

I do not understand when querying 5 rows from a table of 500,000 rows, the following query takes 0.00sec: SELECT id, username FROM Users FORCE INDEX (PRIMARY) ORDER BY id LIMIT 20,5; But querying ...
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1answer
2k views

Postgres nested hstore select query

I have a carts table with items hstore column. An example entry in this column is: carts.items row#1 = { "1614" => {:quantity=>"100", :price_cents=>1655}, ...
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1answer
1k views

How can I make a select statement get blocked?

Hello I am trying to intentionally make a SQL select statement get blocked by another simple SQL delete or update statement, for the purpose of learning. I prefer only InnoDB tables. To prepare the ...
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1answer
424 views

select count(*) in mysql 5.5 innodb— rewrite advice?

I need advice on how to rewrite a select count(*) query for innodb tables mysql 5.5. in new environment its very slow... select count(*) from mails3 join questions using (question_id) where ...
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1answer
3k views

MySQL Explain: Using index, using temporary, using filesort. Can this query be improved?

I'm working on a event tracking system which uses a handful of lookup tables as well as the primary logging table. In a report I'm writing, an object can be selected to view statistics against. The ...
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2answers
489 views

How can we automatically replace a table with a view for a specific user?

We currently have some reports that query a specific table, but one of our users wants the ordering to be different. I don't want to go through and fix each of the reports, because that's rather a ...
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2answers
57 views

Cannot build correct SELECT in MySql

Please help me to create a correct MySql query, which I failed to do. I have 2 tables in our DB: CREATE TABLE IF NOT EXISTS `user_audit` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, ...
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1answer
41 views

Insert into a DB that was selected via other DB?

I have a table that stores what database should I use for a given device( specified by its IMEI), like this: imeiDB( IMEI VARCHAR(15), db VARCHAR(100)); Let's say I have the database ...
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2answers
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MySQL - SELECT on MyISAM Table on index - Does table size (rowcount) matter?

I was arguing with a coworker if SELECT * WHERE t BETWEEN ? AND ? on a MyIsam table where t is an index is significantly slower for huge tables. The hypothetically returned dataset is always the ...
2
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1answer
212 views

Better way to select from nested tables in PostgreSQL

I have the following schema with millions of rows in the match table and each match have two sides (away and home). I want to create a view which shows the most significant data regarding the matches ...
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1answer
461 views

How to speed up slow query using GROUP BY and CASE?

I'm not very experienced with MySQL and and trying to figure out how to speed up a slow query using GROUP BY and CASE statements. CASE 1 -- GROUP BY and CASE SELECT SQL_NO_CACHE m.id, m.sku, ...
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2answers
61 views

How can I simplify this UNION?

Here's the case - I have the following query: SELECT DISTINCT post_id FROM ( ( SELECT DISTINCT rp.post_id, pm.meta_value AS premiere_date FROM wp_related_people AS rp JOIN ...
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1answer
2k views

Mysql search matching multiple values in multiple columns

I need to speed up a search. Currently we let our users input a name: John Doe Then in Java we split that string to create multiple values (or "terms") ["John", "Doe"] and loop through the terms ...
2
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2answers
209 views

Why is this MySQL SELECT performing so slowly despite indexing?

I have a large MyISAM table A (500m entries) that connects two other tables B,C with a n:m relation. So my table A looks like this: CREATE TABLE `A` ( `id_b` int(10) DEFAULT NULL, `id_c` int(12) ...
2
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1answer
513 views

How can I use running total aggregates in a query to output financial accumulations?

I am attempting to write a query that will be consumed by a SSRS 2012 report. Given a paid invoice, with a certain set of account allocations towards which the money paid towards it must be saved, I ...
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2answers
116 views

Get count of processed queries

I have been searching a while to find a way to retrieve the amount of queries my postgres database is processing and responding to. I found various statistics about disk I/O, insert/update statistics ...
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2answers
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To select from all tables inside the schema in PostgreSQL

Is it possible to select from all tables inside the schema? I got all the table names from select table_name from information_schema.tables but I am unable to use it to do my query.
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1answer
2k views

Selecting minimum value using a subquery

I need to write a query to grab the lowest price from each merchant and output the price link (p_link) and some other information such as merchant name + rating. We have a table for prices ...
2
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1answer
427 views

Help with SELECT queries

I need help with some queries. I struggled do find out how to do it, but I think I finally caught on or at least got the results I was looking for in the database. These are the tables (given by my ...
2
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1answer
3k views

Simple Oracle query hangs depending on WHERE clause

Not used to using Oracle, but we have a large database where a non-unique query like SELECT * FROM employees where department = 'HR' is working, results list up no problem. But when I do ...
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1answer
399 views

select for update gives error on indexed column

here is my code: mysql_query("start transaction"); $q="select max(id) from test for update"; $r=mysql_query($q); $row=mysql_fetch_array($r); for ($k=0;$k<100000;$k++) { $q="insert into test values ...
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1answer
419 views

Does mysqlhotcopy block SELECT statements from different clients?

I would like to create a backup of different MyISAM tables on a server using mysqlhotcopy. These tables are about 6GB in size. I would like to know, does mysqlhotcopy block users from SELECTing ...
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32 views

How to order by fields of joined table while selecting for update?

For selecting some rows of table Fwt_Chipkarte for update I use the following SQL statement (IBM DB2): SELECT o.Archiviert, o.Id, o.IdComm, o.Kartennummer, o.Konto, o.LetzteAenderung, ...
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0answers
425 views

mariadb out of memory crash

I have recently migrated from mysql (5.5.36 MySQL Community Server (GPL)) to MariaDB (10.0.10-MariaDB-1~wheezy), along with switching my cloud hosting provider. Both machines have 2GB RAM and 1GB ...
2
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1answer
4k views

I have to update all the rows of a Column in a table. Here is my query

So My tables are People: People_name(VARCHAR 100), People_id (INT, PRIMARY KEY AUTO INCREMENT) Tracks: Track_id(INT PRIMARY KEY), People_id_references (int ,Foreign key references ...
2
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0answers
200 views

Get all comment.message, status.message, users.* and profiles.* where users.user_id exists in friend.friend_id or friend.user_id

I need some help building this query because it's a bit complicated at least for me. I need to get all comment.message, status.message, users.* and profiles.* where users.user_id exists in ...
2
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1answer
59 views

Select last row for a certain group

I have two tables: Table users columns | type | notes --------|--------|------- id | bigint | PK ... | ... | ... Table events columns | type | notes ...
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4answers
17k views

Retrieving row count without using Count function

I wrote a query below which shoots me a syntax error why would it do so, SELECT MAX('Row') FROM (SELECT ROW_NUMBER() OVER(ORDER BY ID DESC) 'Row' FROM USERS) Error Desc: Incorrect syntax near ...
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2answers
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How to delete rows from a table when we're joining and return data?

I have two queries: The first one is as below: SELECT * FROM batch bp INNER JOIN sender_log sl ON sl.id=bp.log_id AND bp.protocol='someprotocol' The second query is used to delete rows: ...
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Manage select results in sql

We need to manipulate a set of records returned from a select query. This can be done in : Either by saving the whole record to a table variable and then do the required process. We can do like this ...
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3answers
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Select query to retrieve values even if are null

I need some help in a query. Need to retrieve data from 1 table, even if one of the field has null value. Here's an example: Select name, SUM(credit) as credit From expenses Where name like ...
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2answers
52 views

Select rows from T such that sum(T.quantity) is greater than an argument

TLDR: I need a way to limit my select such that only rows needed to fill my new order are returned. Hey, I'm looking for a better way to do a query on the simplified toy table below. Right now I do a ...
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2answers
781 views

How to count the rows from 1 table but from two different column

SELECT distinct Major, COUNT(Major) AS MajorCount FROM [College Management System].[dbo].[ApplicantCourseDetails] group by Major SELECT distinct MinorI, COUNT(MinorI) AS MinorCount FROM [College ...
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1answer
7k views

Postgres: How to insert row with autoincrement id

There is a Table "context". There is an autoincrement id "context_id". I am using sequence to retrieve the next value. SELECT nextval('context_context_id_seq') The result is: 1, 2, 3,...20.... But ...