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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What does the term “projection” refer to in an SQL query (or view definition)

In Oracle's document The Query Optimizer, under View Merging, I found the following information The view merging optimization applies to views that contain only selections, projections, and ...
1
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1answer
59 views

Can I parse a text value from a specific column in a query (MySQL)?

I was playing around with Sakila and I ran across the actor_info view and one of its columns is film_info which is a detail of all the movies one actor has worked in. For example a query would be: ...
0
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1answer
155 views

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? ...
0
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2answers
91 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, ...
1
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2answers
297 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
676 views

Insert into table select * from table vs bulk insert

I just wanted to know that SQL Statement INSERT INTO TABLE1 SELECT * FROM TABLE2, will work same like bulk insert ? If no, Is there any way exclude index while inserting records. Process is inserting ...
0
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1answer
69 views

How do I perform a query on a dynamic list of tables?

I have a database named as ( conntrack ) with unknown amount of tables.I have a static table "tabidx" which has one column "date". The following table is static and its name is tabidx which provide ...
0
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3answers
138 views

DISTINCT Role in SELECT

EDIT: @Moderators: Please delete this question. I still feel that it is unclear what I am asking. Maybe I could have used some Venn diagrams in order to describe the problem. The COUNTs do not seem to ...
0
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1answer
55 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 ...
1
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1answer
90 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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2answers
43 views

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 ...
1
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1answer
28 views

select group by with multiple AND conditions on the same columns

I've an sql table like this: SID|SERVICE_SID|ATTRIBUTE_SID|VALUE 1 2 5 "VAL1" 2 2 4 "VAL8" 3 2 3 "VAL4" 4 11 5 ...
0
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1answer
13 views

Numeric cell with 0 not null

I have the following query (in a Oracle Database): SELECT SUM (CANTITATE) FROM ANEXA2A_TABEL2_ROWS WHERE TIP_ACTIUNE = 'COLECTATE' AND TIP_AMB = ...
1
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1answer
59 views

how to cache a subset for cascading select queries in mysql

Here is another database problem I stumbled upon. I have a date-range partitioned MyIsam look-up table with 200M records and ~150 columns. On this Table I need to perform cascading SELECT-Statements ...
0
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1answer
32 views

Grant Select on some columns for specific user

I have a windows group with 20 people and all 20 people in the group were revoked access for some columns in the table. Now I need to add the select permissions for 2 of the users in this windows ...
0
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2answers
37 views

Why does “DELETE WHERE (VARCHAR)=0” execute successfully?

DELETE FROM stats WHERE name=0 "name" is type VARCHAR(64). The above resulted in all records in the table being deleted, instead of just the 10~ that should have been affected. Only that many were ...
0
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1answer
87 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 ...
0
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1answer
133 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 ...
3
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1answer
7k views

how to fetch different data on compare rows of two tables

I have two tables in my database, one is user_app table in which user info are stored, table are as: +--------------+--------------+------+-----+-------------------+-----------------------------+ | ...
1
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1answer
62 views

Oracle: guaranteeing unmodified database state with queries?

If the first word of a SQL statement is either WITH or SELECT, is the statement guaranteed not to change the state of the database? i.e. is this loop "safe"? read SQL string if string begins with ...
-1
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1answer
51 views

SELECT rows with duplicate values

I have a table of names in mysql InnoDB as Firstname Lastname Steve Ross John Doe J. Doe Mike Ross Michael Ross Roger ...
1
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2answers
99 views

How to select data in the same table on different rows that are empty?

I use this select on my SQLite database: SELECT attributeX FROM table GROUP BY attributeX HAVING COUNT(attributeY) = 0; My table: attributeX (type integer) | attributeY (type text) ...
1
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1answer
532 views

MySQL Count rows from another table for each record in table

SELECT student.StudentID, student.`Name`, COUNT(attendance.AttendanceID) AS Total FROM student LEFT JOIN attendance ON student.StudentID = attendance.StudentID I am trying to count the last ...
0
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1answer
200 views

MySQL - How to replace a given value from multiple columns when using SELECT?

I need to SELECT a set of rows of a given table whose structure looks like - 1º line is the name of columns A01 A02 A03 A04 A05 ... A200 99999 99999 10 753 99999 ...
2
votes
2answers
557 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 ...
2
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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 ...
1
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1answer
99 views

Reference column alias in same SELECT list

I'm converting an old MS-Access-based system to PostgreSQL. In Access, fields that were made up in SELECTs could be used as parts of equations for later fields, like this: SELECT samples.id, ...
0
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0answers
148 views

I want to rewrite my MySQL query so that FIND_IN_SET doesn't do a full table scan unless necessary

I want to rewrite my MySQL query so that the last table join doesn't do a full table scan unless necessary. Here's what I mean. Under certain conditions I don't need to select any rows in that join ...
0
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1answer
47 views

on every row on SELECT Query must lookup to other table

I'm working on Login/Logout System and I'm facing this problem regarding on SELECT Query. I have 2 tables namely dtr_tbl and shift_tbl. In dtr_tbl are the logs of the user(login/logout time details) ...
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2answers
48 views

SQL SUM of different product groups in one query?

I have a table with the following columns: PRODUCT_ID | PRODUCT_NAME | GROUP_ID | GROUP_NAME | PRICE GROUP_ID and GROUP_NAME are not UNIQUE. Can I make a selection which just returns each GROUP_ID ...
0
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1answer
74 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: ...
3
votes
3answers
97 views

How does like query work with indexed table

I am working in Spring-java and mysql. I have to query the table of size 100k records. Table has say 10 columns. And In my sql select query I have to make like queries with %text% search on say 4 ...
0
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1answer
50 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 ...
2
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1answer
168 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 ...
0
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1answer
28 views

Padding MySQL queries

I'm trying to retrieve logs of our plant where a certain event has occurred. At the moment, I can query the actual event by using an alarm_code field. However, I'd also like to include about an ...
0
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1answer
89 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 liked server databases. From what I have found online the only proper way to query a linked server is to use ...
0
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0answers
44 views

What is the difference between normal Select query and a Select query inside Common Table Expression(CTE)? [duplicate]

I'm having a table 'Products' and if Execute this query SELECT TOP 1000 [ProductID] ,[ProductDesc] ,[ManufacturingDate] ,[ExpiryDate] ,[Price] FROM ...
10
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4answers
4k views

Benefits of using backtick (`) in MySQL queries?

In MySQL we can create queries with or without the backtick (`) symbol. Example: SELECT * FROM TEST; SELECT * FROM `TEST`; Both works fine in mysql-console. Is there any technical difference ...
0
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1answer
60 views

Slow query while selecting a higher offset from millions of rows

I have sort of security log files containing millions of rows. On my current testing I imported the data for one month which is the sum of ~14,000,000 records. The table contains several set of fields ...
0
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1answer
513 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 ...
0
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0answers
34 views

How to fetch data on a single column from a table having composite key [duplicate]

I am working on a messaging application, where the users can have a group conversation with multiple recipients. So in my database, I have a table called user_message where user_id and message_id is ...
0
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2answers
53 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 ...
2
votes
1answer
185 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
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3answers
666 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 ...
0
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0answers
119 views

SELECT from Function that return CURSOR

I would like to select from a function that return a SYS_REFCURSOR Type value. for example : CREATE OR REPLACE FUNCTION my_funtion ( my_param IN VARCHAR2) RETURN SYS_REFCURSOR IS ...
0
votes
2answers
64 views

How to split a row in a result into mutliple rows

I have the following query: SELECT vs.MonthName AS Month, vs.Region, vs.Category, CAST (MIN (a.TotalAmount) AS money) AS ActualAmount, MIN (a.TotalCases) AS ...
1
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1answer
72 views

How to insert the gathered dates into another table using INSERT SELECT in MySQL?

insert into rfdate (date) select adddate('1970-01-01',t4*10000 + t3*1000 + t2*100 + t1*10 + t0) selected_date from (select 0 t0 union select 1 union select 2 union select 3 union select 4 union select ...
0
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0answers
42 views

Use join to aggregate data from various normalized tables

I have a database as follows: tbl_clients (Primary Key: client_id, Foreign Keys:place_id,district_id,zone_id,country_id) tbl_places (Primary Key: place_id) tbl_districts (Primary key: district_id) ...
26
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1answer
4k views

USING construct in JOIN clause can introduce optimization barriers in certain cases?

It was brought to my attention that the USING construct (instead of ON) in the FROM clause of SELECT queries might introduce optimization barriers in certain cases. I mean this key word: SELECT * ...
0
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0answers
23 views

Need help on transferring data from a PostgreSQL database to a future (to be decided) database!

(English isn't my native language) I'm doing an internship for school and my task is to theoretically describe the best way to transfer the data from their current database (PostgreSQL) that they have ...