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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Run and Save multiple SELECT statements

Within a Postgres function I would like to run a number of SELECT commands. For each SELECT command I would like to output written to separate text files. What is the best way to implement this? ...
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88 views

Is there any performance difference between a group by statement and nested select statements in sql?

I am curious to know about the differences between using group by statement and nested selects to achieve the same result. for example consider I have two tables such as the following: tblPurchase ...
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46 views

How to sum the buy order and sell order in one row per each ticker

I have a table containing some trading information of several tickers and I would like to divide the data into sum(Amount) for buy and sell separately, grouping by each ticker. I have one table ...
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60 views

How do I select the value with SERIAL data type in postgres [closed]

I want to know how to select values from a column that has SERIAL data type. I already try to do that but the output is like this 'Resource id #3', and not just '3' I use SERIAL so I dont have to ...
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89 views

SELECT query with referenced subqueries

How does one reference the currently-grouped by field in a subquery? Consider a table with the following data: Client Status Size 1 A 500 1 B 1500 2 ...
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12k views

MySQL: split value in column to get multiple rows

I have some data in a table like so: product_id categories 10 9,12 11 8 12 11,18,5 I want a select statement that would produce this output: product_id ...
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109 views

Get all items from list table which don't have a successful log entry for 'sent' in log table

How might one retrieve items that when joined either don't have a specific field (sent), or if they do have that field (sent) then they have an additional field (failure_reason) as well for every sent ...
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3answers
100 views

prepared statements are not inserted

i am new to JDBC and trying following code. Could not find the error in it try{ Connection con = ConnectionProvider.getCon(); stmt=con.prepareStatement("insert into ...
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53 views

Should the value of a select max be indexed when the where clause is already indexed

I have a customer_orders table in a schema designed to be shared between multiple companies. Each customer_order has an invoice number that should always start at 1 and increment based on company ...
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299 views

Conditionally limit MySQL SELECT query

My goal is to select rows from a mysql table, but according to certain column. Normal SELECT would be: SELECT ti.id, ti.userid, ti.date, ti.duedate, ti.datepaid, ti.subtotal, ...
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289 views

Order of where clause evaluation

If I have a MySQL table which has content from the last 3 months I actually do the following: SELECT SQL_BUFFER_RESULT SQL_CACHE count(id) cnt FROM `mDelivered` where _campaign = 2 and `session` = ...
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MySQL: Join one Row in a table with two Rows in other table

In my MYSQL Database COMPANY. I have two tables, like below in my diagram (arrow shows relations): `users` `user_login` +--------------+ ...
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108 views

SQL and Multiple Indexes

Consider the following table: i | a | b | c -------------- 0 | 1 | 2 | 3 1 | 4 | 5 | 6 2 | 7 | 8 | 9 3 | x | y | z The table, in the end, will have several thousand rows, and even more columns then ...
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4k views

How can I select the latest record having one state where no later records exist with any other state?

I want to select the last record (by datetime) having a given state where no later records exist with any other state for each given "widget". widget state timestamp ------ ----- ...
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3answers
225 views

How can I select data and the total to cursors?

I have a table like this: ID | Name ------------ 1 | AA 2 | AA 3 | AA 4 | BB I want to select all rows where Name like 'AA' in a cursor and get the count from this result in another ...
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47 views

MySQL: Select two values of two columns and compared their values exchanging them each other

I need to find a way to select one random row where the subscriber is not also leader (in the same or any other row). Something like this: (just to have an idea) SELECT `leader`,`subscriber` FROM ...
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54 views

Efficient way to get last 10 rows of each group in SQLite, can CTE help?

Consider there is a table of job runs history with the following schema: job_runs ( run_id integer not null, -- identifier of the run job_id integer not null, -- identifier of the job ...
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66 views

How to find the price based on the given range

Here i need to find the price of the qty based on which price range the qty lies. In the first date(2015/01/01) 5 quantities have been sold and we made entries from (1 to 5) ,On second day for 10 ...
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34 views

Select Unique Fields with Max Values in Each?

I have a table with names, numbers, and timestamps on the data. I want to know how to select a unique instance of each name based on how recent the timestamp is. Addy (text), NW (number), UDate ...
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40 views

Granting Select access to all tables within a specific Database in MS SQL

I have a server that has multiple databases that are contained within that same server/project. I am using MS SQL Server 2012. I have a special role set up with 3 users that are apart of that role. I ...
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48 views

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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53 views

Prioritizing values in select statement in ORACLE

Due to the JOIN for the communication method (Phone, email etc) we get alot of duplicates because a company can have multiple communication methods (CICM.CLIENT_VALUE). My question is... Is there a ...
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543 views

Lock mysql table to prevent select and insert at the same time

I know this question has been asked earlier and I have also read the documentation. But I guess I'm stupid not understand. I have a code that inserts a row and the row should be unique in several ...
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67 views

Select not repeated results from same tables in different databases

I have 3 tables in 3 different databases which are exactly the same. I'm trying to sync from this 3 databases to a master database as shown in the picture below: Right now I am running the same ...
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92 views

Select last record from my table [closed]

I am new to SQL and PHP. I'm having a problem with selecting the last record from my table. I run the following query: SELECT * FROM 2521118 ORDER BY id DESC LIMIT 1 My table name is 2521118 and ...
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150 views

If in mysql I have string `xxx yyy` - how can I SELECT this if user input `xxxyyy`?

My online-shop in PHP (OpenCart). On site we have product-search. For example product have name iSport 220, and if user search input string is iSport220 we must show this product. And vice versa. ...
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411 views

SQL Server user cannot select from a table it just created?

I'm having trouble understanding permissions in SQL Server (in this case SQL Server 2012, but not sure how version-dependent this issue is). I can create a database, create a login/user on master, ...
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120 views

The cost of left out join versus a select [closed]

I'm currently working with Ebean for database abstraction. My test database is Postgresql 9.3 I turned on logging for the SQL queries to test some code behavior. So, assume 2 tables, OneToMany ...
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83 views

Select range of non-identical date from different table

On MySQL5 with innoDB, I have sensor data in multiple tables, all with an ID and a DATETIME field, like so (two tables shown, but there are more). The IDs and DATETIMEs are not identical between ...
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142 views

CONCURRENT SELECT's SLOW … LOCK IN SHARE MODE

My Table has 25 Million rows total and 6 million rows satisfying below where clause. Select 1: select max(stamp) from Table where type = "string" LOCK IN SHARE MODE ; 6000+ seconds Select 2: ...
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72 views

Replace nested “select with count” with outer join? is this possible?

SELECT c.classid , c.classname , (select count(s.id) from students s where s.classid = c.classid and status = 'failed') as noOfFailed, (select count(s.id) from students s where ...
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1k views

Select rows from table where each row refers to a different schema

I have customer table in public schema. And I have a schema named after each customer. Each customer schema contains different tables like portals, plugin, ... When I want to select portals used by ...
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59 views

Searching a database safely using SELECT

I have a site that allows users to search the database for several items. However I am not that good with SQL and I have read that allowing user to type in boxes that then use "SELECT-statements" is ...
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299 views

How to make a single row result query to return multiple rows

I have the following WITH SQL Query which does select a set of filling stations along a route within the distance of 1000m. To have the measurement in meter I cast the geometries to geography. I also ...
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85 views

4 tables, find department with the highest average salary [closed]

ABC is an organization operating in a certain country. Below are the data for the database that manages the information on this organization's employees: employee(employee_name, street, city) ...
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21 views

Selecting one variant out of different similar results

I have a table that looks as follows: Book Format Contents A html ... A markdown ... B html ... C markdown ... I want to return only 1 version of a book. ...
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765 views

Processlist show most of the queries are sending data for select query

I have faced some problem like sending data state in processlist. In my application I used parallel processing which send 50 count at a time, and that will do some MySQL database operation (select and ...
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1answer
26 views

Copy every entry from TableA to TableB where the ID is in a textfile containing a list of IDs

I have a text file (or an xls) with a 35k lines, each containing a single ID. I'm required to copy every entry of TableA to TableB where the ID is in said list. Would it be best if I'd create a new ...
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332 views

Columns count in SELECT query and SQL Server buffer cache

Let's assume that I have a table with 30-50 millions records. It has ~40 columns. Currently when I request data it always requests all columns because of legacy ORM that we use. I know that if we ...
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321 views

Select all results from two independent tables

I have two tables: Comments -------- id comment_content time_stamp Activities ----------- id activity_content time_stamp And I would like to combine the results from both, ordered by their ...
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27 views

How can I get all rows of data not included in a TVP

I am trying to do the following: declare @domains DomainNames; declare @CompanyId int declare @CompanyName varchar(255); declare @deletedList DomainNames; set @CompanyId = 239; set @CompanyName = ...
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1answer
143 views

Select * from (every table in an subselect)

I was trying to get an select * from (for column table result) every table_name with the result bellow, how can i achieve this? (SELECT a.table_name FROM all_cons_columns a JOIN all_constraints c ...
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1answer
456 views

Mysql Select vs Select SUM performance

I need to check whether the surfer has alrady voted this can be done using Method 1 Select record_num FROM table where etc etc. i.e. SELECT record_num FROM content_votes_tmp WHERE up = 1 AND ip ...
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176 views

Select latest record for each ID

I have three tables that contains data as below: Users Id Name Other_Columns --------------------------- 1 John Blah 2 Ricky Blah 3 Stella Blah 4 Bob Blah Saldo Id ...
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357 views

What's the difference between INSERT … SELECT and SELECT INTO

Let's say I have a table item and an other one versionned_item. From time to time, I want to copy data from item to versionned_item. What I did is WITH subset AS (SELECT ...) INSERT INTO ...
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2answers
21k views

SQL insert into … values (…, select(…))

I am trying to insert 25 users, user1...25 into Members with the same GR_ID = 2 with command: insert into MEMBERS (GR_id, username) values (2, (select username from USERS where username like ...
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226 views

MySQL select with left join query

I have following code. select class.name as classname, class.hours as hours, teachers.first_name as teacherFirstName, teachers.last_name as teacherLastName from teachers,class left join ...
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33 views

Get the most present elements from many fields

Here is my table: id|item0|item1|item2 --+-----+-----+----- 1 | 10 | 12 | 12 2 | 12 | 68 | 13 3 | 15  | 13 | 10 I just want to get the most present number of all itemX columns. The query ...
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68 views

Selecting 3MB (or more/less) data from database server

I installed PostgreSQL Server on my Windows 7 machine. I created database and a simple table, and populated the table. Now I want to connect through the network with my Postgres server and select a ...
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71 views

MySQL locking tables / rows on select statement

I have a web app that does an addition to a field based on a user input. So say for example User-A inputs 7, my web app would first query the contents of the field for the current number in there, ...