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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469 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 ...
3
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3answers
92 views

SELECT + INSERT or INSERT alone

I have an application where several devices send data every second to my server. On the database I have a table with the devices and another table with the data sent every second. The first time a ...
3
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2answers
113 views

SQLite Like clause match whole word only

I have a SQLite database with a table named: minecraft +----+----------------------+ | id | name | +----+----------------------+ | 1 | Pocket Mine MP | | 2 | Open Computers ...
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5answers
22k 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 ')'...
2
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5answers
402 views

How define select, if bridge pair may have 3 players?

Normaly a pair has 2 players, but if there is an odd number of players at the club, one 'pair' has 3 players. Table, members: pair, player_id 1 1 1 2 2 3 2 4 3 5 3 6 4 7 4 8 5 9 5 10 6 11 6 12 6 ...
2
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2answers
78 views

CTE To Use Alternate Select When Select Returns No Rows

I have created a involved CTE, no recursion, with multiple selects being done as it processes the business logic of the requirement. But I have been advised that the logic needed for the scenario ...
2
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3answers
2k views

How to query efficiently from Postgres to select special words?

Let's say that I have a table called words with very many records. Columns are id and name. In the words table I have for example: 'systematic', 'سلام','gear','synthesis','mysterious', etc. NB: ...
2
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4answers
416 views

WHERE NAME LIKE ( A SET OF NAMES )

I would like to drop all the jobs related to a set of specific databases. So I have added all the names into a table variable and I was trying to generate the scripts to drop the jobs. how can I ...
2
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3answers
348 views

Using expressions in the SELECT list to thin down a CASE statement

I have a query I'm working through rewriting - it has a huge bunch of case statements in the select list that all basically look like this: select Column1 = case when (Something = 2) and ...
2
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2answers
4k views

Insert into … (…) (Select…) on duplicate key update

Can you help me to solve a problem. The task is to insert a record in MySQL database. terms: If the record exists - to update the record. If the record does not exist - to create a new one. ...
2
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3answers
87 views

Platform independent select ordered by primary key

Is there a reasonably standard way to perform a select on a single table and have the result set ordered by primary key without having to specify the primary key condition explicitly? Ideally I wish ...
2
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1answer
3k views

SQL Select WHERE row updated

USE [RF_WORLD] GO /****** Object: Trigger [dbo].[lastdeathtrigg] Script Date: 08/20/2012 10:52:58 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO -- =======================================...
2
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1answer
753 views

How to avoid duplicating information in a series of nested SELECT statements?

I'm working on an SQL query that puts together customer history based on past purchases (the industry is venue ticketing). The report will be LARGE, something like 80-90 columns, with one column per ...
2
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2answers
2k views

Is there a benefit/drawback to adding LIMIT 0,1 when performing SELECT on unique key field?

I am using a MySQL database and perform many select like these: SELECT MyField FROM MyTable WHERE MyKey = 'some_value'; The purpose is to retrieve a field a value if the corresponding row exists. ...
2
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2answers
2k views

How expensive are SELECT FROM LIKE statements from a design perspective?

I have a situation running out of control regarding an ever increasing number of small static files I need to access randomly in a large directory structure. I MUST reduce the number of those files ...
2
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2answers
190 views

How do I set the isolation level for SELECT statement?

Using PostgreSQL 9.5 I would like to make sure that when I run a SELECT statement I get consistent results, i.e. if the table is modified while the SELECT is running, I want to get the state that was ...
2
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2answers
2k views

MySQL - How to check whether all values of a given SELECTed row are equals? [closed]

Using MySQL, how can i SELECT all rows whose values are equals ? For instance, suppose a SELECT of a given table as follows COLUMN_A COLUMN_B COLUMN_C ... COLUMN_N 1 2 4 ...
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3answers
1k views

How to speed up a multiple select query

EDIT - Putting my whole stored procedure: I have the below stored procedure: CREATE PROCEDURE [dbo].[data_Update] @Owner NVARCHAR(255), @ID VARCHAR(255), @Division VARCHAR(255), @Manager ...
2
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1answer
25k views

Select Multiple Values from Same Column; one sql statment

I am looking to return a list of users from a database. There are hundreds of users in the db. Each user has it's own unique user_id. All of the values that I am trying to return reside in the same ...
2
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2answers
2k views

Select rows with repeat data within certain timeframe

As a follow-up question to my previous question on difficult row categorisation, I have another problem which I'm sure will be easily solvable. After this I plan on reading a good book or two on ...
2
votes
2answers
105 views

Select random rows up to a limit

SELECT * FROM my_players WHERE player_type = 'IF' ORDER BY cardweight / rand() DESC limit 3 That is my current query, What I am trying to do is select random rows for which I have the * in my query, ...
2
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2answers
92 views

Query to know who paid more than 10k

I have a table with payment informations, like this: ID COSTUMER_ID DATEPAID AMOUNT 1 1 2012-01-01 50 2 1 2012-02-01 100 3 1 2012-03-01 70 4 2 ...
2
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3answers
82 views

Generate a list from columns that do not contain a zero for each row

I have a table TAB1 in an Oracle database: +----+----+----+----+----+----+ | ID | C1 | C2 | C3 | C4 | C5 | +----+----+----+----+----+----+ | 1 | 1 | 0 | 3 | 0 | 5 | | 2 | 11 | 22 | 0 | 44 | ...
2
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1answer
566 views

Difference data between adjacent rows

I have a table (called Visits) with ReqTime DATETIME NOT NULL column AND Duration INT UNSIGNED column. Duration should be set to the difference of ReqTime for two adjacent rows. But Duration is not ...
2
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3answers
6k views

Select query takes more time than it should

I have a MySQL database table with nearly 23 million records. This table has no primary key, because nothing is unique. It has 2 columns, both are indexed. Below is its structure: Below is some of ...
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2answers
2k views

Optimized query to fetch a record from 10 million entries

A table has 2 fields | UniqueKey | TimeStamp | ------------------------- | xfsddddq | 1024125412 | | xfstttdx | 1024125413 |< | xfsdxxau | 1024125415 | Estimated, there are 10 million ...
2
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1answer
3k views

MySQL error in where clause : Unknown column

When I try to execute the query below, I receive the error message: Unknown column 'have_discount' in 'where clause' My query is: SELECT DISTINCT(MP.item_id), item_title, item_user_id, ...
2
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2answers
74 views

Are these extra Index fields needed?

I've designed a table as below for users who register a quiz: CREATE TABLE `registered_quiz` ( `rq_id` smallint(5) unsigned NOT NULL AUTO_INCREMENT, `user_id` smallint(5) unsigned NOT NULL, `...
2
votes
1answer
814 views

T-SQL, show a set of rows (specific column) as a field, for a better desc, please see the table relationship

I have been having a problem for quite a while now, that I can show with a sample of 5 tables (I'm actually dealing with more than 5!): -------------------------------- shipments ...
2
votes
2answers
359 views

How do redundant indexes impact query performance?

The indexes are affecting the ADD/UPDATE operations however I was wondering whether the redundant indexes will affect the SELECT query performance or not? How the redundant indexes are handled by ...
2
votes
1answer
231 views

Query table A for any rows that are like any search term in table B

I need some help writing a select statement (I still don't think in sets!). Here's the scenario: I have table A with column "Name varchar(20)". I have table B with column "SearchTerm varchar(20)". I ...
2
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3answers
112 views

Poor performance of JOIN, WHERE, ORDER BY combination (MySQL)

Goal: select 10 most recent rows from posts which are related to a specific user. There are two tables: posts (~5,000,000 rows) and relations (~8,000 rows). posts columns: --------------------------...
2
votes
2answers
97 views

Search multiple values in multiple columns

I have a table results with this fields: id results_id number_one (int) number_two (int) number_three (int) number_four (int) number_five (int) Each number_* column can contain a number from 01 to ...
2
votes
2answers
1k views

SELECT and UPDATE in a single query while updating selective fields of duplicate records only

I have a MySQL table named Contacts_table with, say, the following contents: ID NUMBER NAME CITY 001 2222222222 John Doe Los Angeles 002 ...
2
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1answer
8k views

MySQL query to evaluate ranges in date and time elements of a datetime column separately

TABLE EventID, EventTime (DATETIME) 1 2013-09-29 23:55:00.0 2 2013-10-01 00:05:00.0 3 2013-09-29 23:55:00.0 4 2013-09-29 23:45:00.0 5 2013-10-02 23:05:00.0 6 ...
2
votes
2answers
2k views

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 ...
2
votes
1answer
130 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. ...
2
votes
1answer
894 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
votes
1answer
253 views

Search within same ID across several rows

My table has the following structure: +----+---------+------------+-------------+ | id | word_id | meaning_id | sentence_id | +----+---------+------------+-------------+ | 1 | 1 | 15333 | ...
2
votes
1answer
106 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 ...
2
votes
2answers
122 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 ...
2
votes
1answer
482 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 ...
2
votes
1answer
8k 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. ...
2
votes
2answers
125 views

“For each group of results fullfilling condition X, select only result with smallest column value A”

I have a table with data and dates like so: DECLARE @p TABLE (P_key int, P_Data char(1), P_ValidUntil datetime) INSERT @p VALUES (20, 'T', '2003-02-28') INSERT @p VALUES (21, 'U', '2005-05-31') ...
2
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1answer
49 views

How to JOIN a table with a name that equals to a determined value in MySQL?

The model of the (PHP & MySQL based) Zend Framework 2 application I’m currently working on contains a inheritance similar to the one described here. To map this to the database I’m using the ...
2
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1answer
43 views

Join two SELECT results with the same post_id value

I need to do a query to the MySQL database of my site built in WordPress / WooCommerce. The 'wp_posts' table keeps products, articles and more. Every row in 'wp_posts' has a 'post_id' to connect '...
2
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1answer
42 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 ...
2
votes
1answer
189 views

Alternatives to Linked Servers (Allow Inline SQL with Parameters)

I am trying to find a solution to execute inline SQL with parameters against some linked server databases. From what I have found online the only proper way to query a linked server is to use ...
2
votes
1answer
491 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
votes
1answer
307 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), ...