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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Gets records by max date and hour

I have this query: "SELECT * FROM `" . $table . "` WHERE STR_TO_DATE(data, '%d/%m/%Y')=(SELECT max(STR_TO_DATE(data, '%d/%m/%Y')) FROM " . $table . ") AND hour=(SELECT MAX(hour)-".$delta_hour." ...
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228 views

Getting the top count of records from a table for each month and user

I have a table where translations are stored along with the user_id and when the translation was added. I want to create a query that shows the 'Translator of the month' (the person who did the most ...
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46 views

SQL SELECT - adding field to SELECT with JOIN is changing the results

I have a SQL sentence with JOIN, running on mysql 5.5.16: SELECT DISTINCT (ot.orders_id), ot.value FROM orders_status_history osh INNER JOIN orders_total ot ON ( osh.orders_id = ot.orders_id ) WHERE ...
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3answers
614 views

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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36 views

Select and sum from related columns

I have table with the following columns: date (month), hours/days (31) and daily tasks (31) Columns: date day1 day2 day3....task1 task2 task3.... Records: june 4 6 2 .... run walk ...
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2k views

How to select only first column dynamically on mysql

I have to select only first column. Because of i dont want to select all columns like SELECT * FROM table. But my first columns may vary like following: id article_id user_id product_id page_id etc.. ...
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81 views

Name for SELECT equivalent of UPSERT

UPSERT means INSERT and\or UPDATE, is there a standard name for a sproc that will INSERT if necessary and then SELECT? e.g. I want to get the IS of a row that matches fields and give me the ID, if ...
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4answers
50 views

Null Or Multiple Parameters When Querying

I have a stored procedure that has a parameter that must take a comma delimited varchar list of values that can be turned into a table of values or can be NULL, such as @Values VARCHAR(10) = NULL ...
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1answer
2k views

Select records in one table but not in another, when the second table is not matching on primary key

I have two tables from which I need only the results that appear in one table (list) which do not appear in the second table (cardinal). The list table's primary key is sku, and the table has a ...
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8answers
7k views

Is select * still a big no-no on SQL Server 2012?

Back in the days of yesteryear, it was considered a big no-no to do select * from table or select count(*) from table because of the performance hit. Is this still the case in later versions of SQL ...
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0answers
27 views

Multiple selects ordering desc from single table

I'm trying to do multiple selects to give multiple ordered columns. I'm struggling to get the below mysql query to achieve the output I want. SQLfiddle: http://www.sqlfiddle.com/#!2/a1002/3 ...
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666 views

how to grant select access my sql server

when I exec the syntax to gain the access I get an error that I cant grant permissions to my self. any Ideas please!
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27 views

Is a commit or abort more costly for a prepared select?

I have found that selects will actually generate WAL records upon commit. Are there other costs to committing a select? Are there costs due to an abort? If so, which has more? What would be the ...
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0answers
45 views

Will a serializable read only deferrable select block?

I'm unsure from the documentation and wiki if a serializable read only deferrable select, a SELECT preceded by SET TRANSACTION ISOLATION LEVEL SERIALIZABLE READ ONLY DEFERRABLE, will block a ...
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1answer
25 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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1answer
20 views

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

I wanna ask how to select coloum 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 input ID like when ...
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0answers
11 views

How can I check the size of my SELECT query? PostgreSQL

I know how can I check the size of my database, called test: SELECT pg_database.datname,pg_size_pretty(pg_database_size(pg_database.datname)) AS size FROM pg_database where datname='test'; Now, I ...
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2answers
38 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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41 views

Using the “Select Top (100) percent vs. Select * , or selecting any column” [closed]

I wrote the first query below that I was hopeing to give me the exact same results that the 2nd query does, but it seems there is one recrod different: SELECT DocumentSourceName FROM ...
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2answers
366 views

`Select` query take 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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1answer
150 views

Restrict access to rows by usename

In my database i store data of different users (e.g. addresses or invoices) in the corresponding tables. I want to make sure that a logged in user only has access to it's own data in the tables (so ...
0
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1answer
34 views

How to get desired type of records for desired number of times in oracle

I want to get get 6 "double_scoring" records and 4 "singe_scoring" records from my Profiles table based on SCORING_RULE column values. Can you please let me know how can I do this with SELECT query ...
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1answer
61 views

Mysql Select table records which have not been updated since last month

I have a table names 'scoredata' having fields id, lessonid, levelid, studentid, addedate in which score for each day will be entered by the admin. I want to select only those studentid whose score ...
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2answers
72 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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1answer
73 views

Select historical prices for an exact datetime - MySQL

I have a price_list table where I store historical prices for each item. columns are - id, name, price, start_date, item_id When a price is changed, a one new row is inserted with a current ...
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1answer
51 views

Running queries directly on DB2 databases

Just have a general query, if it is really fine or safe to run long select queries on RDBMS production Databases specifically DB2? If NO, what are the major risks and issues in executing select ...
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2answers
2k views

How to select specific rows if a column exists or all rows if a column doesn't

I'm writing a script that gets a count of rows for a few tables, however for some tables I want to only get a count of rows where a flag is set (in this case active=1). Is there a way I can do this ...
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4answers
3k views

Recursive self joins

I have a comments table, which can be simplified down to this: comments ======= id user_id text parent_id where parent_id is nullable, but might be a key for its parent comment. Now, how can I ...
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1answer
27 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, ...
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1answer
20 views

How to return a result set from oracle procedure ?

How can i return a result set from a stored procedure in oracle ? suppose i want to return a table from a simple select statement such as this : Select * from tblTest I tried this but this seems ...
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2answers
129 views

multiple select query for the same tables with union [closed]

Using below query i want to find out the top number of students from each catagory(SC,ST,OBC,etc) on plus2percentage basis. eg i want top 3 students from SC catagory, top 2 from ST and Top3 from OBC. ...
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2answers
76 views

Multiple SELECT vs single SELECT over TCIP

My question is a performance one: I need to select roughly 400+ rows, i know their ids. currently i loop in code and fire off multiple queries over tcp/ip - because its easy: ... select [columns] ...
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1answer
44 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
2k views

Getting unique names when the IDs are different (DISTINCT ?)

I've got this table: id | name 1 | John 2 | John 3 | Peter 4 | Mike 5 | Mike And I want to get the unique names, getting the latest one in the list. I could go for: SELECT DISTINCT name ...
4
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0answers
193 views

SQL Server Deadlock - Two SELECT Exclusive Locks on Exact Same Index and Key

How is the deadlock graph below possible? How did two SELECT statements simultaneously acquire an exclusive lock on the exact same resource? The exclusive locks were on the primary key index for ...
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1answer
140 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 ...
2
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1answer
54 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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25 views

SQL Get result as a column

Is it possible to get a result as a column? The SELECT query will only need to return one record, however, at the time of querying the database it will not know what attributes are in the table, and ...
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0answers
145 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 ...
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1answer
2k 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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1answer
62 views

ORDER BY that doesn't contain repeating values

Relevant SQL Fiddle (postgres 9.2) How do I state a SELECT .. ORDER BY .. that avoids having repeated values for a column? That is, for rows of the column "rank" (1,3,3,1) how do I get a result so ...
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9 views

Improving the performance of this select query [duplicate]

i have two tables TABLE 1 and TABLE 2 And i am running this select query to fetch the data , it takes long time to run SELECT TABLE1.* , TABLE2.COL1 , TABLE2.COL4 FROM TABLE1, TABLE2 WHERE ...
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2answers
88 views

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: ...
2
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2answers
122 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) ...
0
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1answer
37 views

Design for hierarchical embedded database

The goal is to construct a hierarchical database of Objects having the following format: TypeA -> ObjectA [values, contains ObjectB*, ObjectC*, etc.] TypeB -> ObjectB [values, contains ...
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106 views

select specified number of unique IDs where second column is unique

Look at the following example starting from the top row (id=9) and work your way down, selecting a limit of 4 rows that have sec's that we have not yet seen. We "select" id=9 because we don't yet have ...
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1answer
122 views

How to improve the performance of this select query?

I have two tables: TABLE1 and TABLE2. And I am running this select query to fetch the data. It takes long time to run: SELECT TABLE1.* , TABLE2.COL1 , TABLE2.COL4 FROM TABLE1, TABLE2 WHERE ...
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1answer
52 views

Low-level relational operators from SQL

I have been asked to outline the sequence of commands using low-level operators (join/project/select) that are used in the following SQL statement; SELECT d.name, k.city FROM DOG d, KENNEL k WHERE ...
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52 views

SELECT, PROJECT, CARTESIAN PRODUCT and JOIN

I have the following tables; DOG +----------------------------------------------+ | Name Type Age Kennel_name Owner_name | +----------------------------------------------+ ...
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3answers
64 views

How to create an Access query to find # symbol into a field?

It seems easy but I'm missing something. I have a MySQL database that is connected from access through ODBC connector. I'm looking for the fields where there are # symbol but I'm getting zero ...