Structured Query Language (SQL). For questions about the language, not Microsoft SQL Server (tag sql-server).

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Postgresql Database on external HD

I'm completely inexperienced with PostgreSQL, but have to do some work on it, and I have been googling for a solution for almost two days. I hope someone here can help me out. I have a PostgreSQL ...
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1answer
365 views

How to remove object from json array?

My table: CREATE TABLE items ( id BIGINT PRIMARY KEY NOT NULL, name VARCHAR, images json ); images format: [ { "id": "owner", "full": "<url>", "thumb": "<url>...
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1answer
604 views

Merge 2 tables and fetch data one by one

I have two tables: product & offers. products has (prod_id, category_id, prod_name, brand, price, status) offers has (offer_id, prod_id, offer_type, discount_amt, validity) I want to display ...
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1answer
328 views

Full text search on multiple joined tables

I'm trying to set up a full text search in PostgreSQL but coming across the problem that the more tables I join to the query the fewer the results I get back. The tables I am trying to join are: ...
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1answer
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Cascading Inserts in MySql

I have a users table that has a one to one relationship to a user_preferences table (primary foreign key user_id). When a new row is added to the users table (new id added), is there a way to setup ...
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Is it possible to query value of SQLNET.EXPIRE_TIME parameter?

Can somebody advice whether it is possible to query for current value of SQLNET.EXPIRE_TIME parameter in Oracle 11 DB? Should select * from v$parameter return value of SQLNET.EXPIRE_TIME (if it ...
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2answers
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Identify rows that match on a key but differ in other columns [duplicate]

Supposed I have table temp A and table temp B: IF OBJECT_ID('tempdb..#A') IS NOT NULL BEGIN DROP TABLE #A END IF OBJECT_ID('tempdb..#B') IS NOT NULL BEGIN DROP TABLE #B END CREATE TABLE #A ( ID ...
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1answer
223 views

Entity ID field that can refer to multiple tables?

In designing both audit tables and notification tables, I've run into an issue where I need a row to refer to an entity in another table, but which table that entity is isn't always the same. For ...
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350 views

optimize the query with big and low cardinality

I have big enough dataset and few joins to get them all with help next query: SELECT DISTINCT c.c_id FROM c_active z1 INNER JOIN cs c ON (z1.cv_id=c.cv_id) INNER JOIN indi i ON (c.m_id=i.m_id) INNER ...
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1answer
385 views

Select post and concatenating all categories it belongs to

I have 3 DB tables POSTS +----------+----------+----------+ | id | title | content | +----------+----------+----------+ CATEGORIES +----------+----------+ | id | title | +---------...
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159 views

Embedded select with rank

I am having the hardest time following the tutorials on this site regarding ranking with MySQL. I have a larger problem than others seem to show. My table is constantly updating with single answers (...
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171 views

Allowing users to compile / run PLSQL and SQL

As a DBA - assuming my users are knowledgeable with PLSQL and SQL - why would I not grant my users privileges to compile and run their own PLSQL code. We have an MI database environment where the data ...
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Which schema is better for a shopping project? [closed]

I'm working on a business-to-customer project that has variety of product types. There are a few properties like name, description, brand_id that each product has but there are also many specialized ...
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1answer
836 views

Find columns with different values compared with a reference row

My table, MARC, has more than 200 columns with WERKS (plant) as the key. Most of the entries in MARC have values that come from a reference plant. So, usually, all the 200 columns will contain the ...
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1answer
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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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How to get dates between two dates from MySQL table?

I want to get dates between two dates from MySQL table EXAMPLE fromdate(2015-01-01 and so on....), todate(2015-01-10...and so on) are the columns i have to get dates between these two columns. ...
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1answer
77 views

Group when there are multiple items by a particular user within a certain timeframe [closed]

SELECT * FROM ( SELECT articles.id, articles.author_id, users.username, COUNT(articles.id) AS number_of_articles, GROUP_CONCAT(DISTINCT articles.id) AS articles_published FROM articles ...
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4answers
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Why should a key be made explicit?

I am very new to the subject of databases so this may sound ignorant, but I am curious why a key should be made explicit within a table. Is this primarily to tell the user that the given column value ...
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2answers
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Order by column should have index or not?

I have added indexes to table which are used for searching result. I am showing results by ASC or DESC order. So that column should have index or not? I have 2 more indexes on that table. How ...
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2answers
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Implementation of a many-to-many relationship with total participation constraints in SQL

How should I implement in SQL the scenario depicted in the following Entity-Relationship diagram? As it is shown, every A entity type occurrence must be related to at least one B counterpart (...
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1answer
23k views

Stored Procedure to return dynamically created table data

Quick back story, we are working with an outside vendor that has a survey system. The system is not necessarily designed the best in that when you create a new survey and the system creates a new ...
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2answers
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How does using separate schemas affect SQL Server 2008 performance?

I want to use separate schemas for objects with different purposes in our SQL Server 2008 database. Right now we use a fairly mind-numbing naming convention to indicate the purpose of a table or ...
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2answers
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Updating 700 million rows to same value

I've got a data warehouse (oracle) where I need to set a column to the same value for all 700 million rows. I don't have admin access, or access to an admin, so this needs to be accomplished with ...
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4answers
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How do I do a complex GROUP BY in MySQL?

I have a table that contains several keys into other tables (where each key is comprised of multiple columns). I would like to be able to group rows together that have an equal key, but I don't want ...
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6answers
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How do you submit a List of items to a Stored Procedure to limit results? [duplicate]

Possible Duplicate: Passing array parameters to a stored procedure Lets say you want to filter results by a List of uniqueidentifiers such that your SQL statement would read: WHERE CustomerID ...
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1answer
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Why not rebuild indexes with page count <1000?

I use Ola Hallengrens script for Index maintenance. Before I did that, I used the following query to see which indexes are fragmented most: SELECT dbschemas.[name] as 'Schema', dbtables.[name] as '...
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Database locking issues?

I have run into a transaction related issue on a SQL Server 2008 production database. A brief overview is that we have a website that has numerous concurrent users around the state, who do GUI type ...
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4answers
8k views

Do SQL Server stored procedures cache data results?

I have heard this from friends, but I never investigated whether this is true. Is it true that the data results of an executed query are stored in cache? I mean, if I have a stored procedure like : ...
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2answers
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Using totals on aggregates to improve performance

I have two tables: details and totals of these details. Details (Slow solution): select OrderId = r.OrderId , TotalQty = SUM(r.Quantity) , ...
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1answer
323 views

Table order in Join Query

if i say: Table1 left join Table2 is it the same as saying Table2 right join Table1 ? In other words, should i expect to get the same results from 2 identical queries where the only thing that is ...
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2answers
397 views

Why do we have SHRINKDATABASE command in SQL Server

I have read across the internet where Finest Developer says shrinkdatabse should be avoided as it causes increase in fragmentation and decrease in performance . I would like to know from you guys ...
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2answers
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Using Foreign Key and References for ON DELETE CASCADE in mysql

I was thinking that these two ways for creating foreign keys are the same CREATE TABLE child1 ( id int(11) not null auto_increment, parent_id int(11) REFERENCES parent_table(parent_id) ON DELETE ...
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7answers
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Database table and NULLs

I know that there have been many opinions/sides concerning NULL values in a database. I have not understood though what is the best practice for this. I.e. if I have a relational table with an ...
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2answers
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Create smaller row from alias and preserve column names

Using Postgres: SELECT users."name" AS "name" , array_to_json(array_agg(sites)) as sites FROM remodel.users AS users JOIN remodel.user_sites AS user_sites ON users.id=user_sites.user JOIN ...
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3answers
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“lock request time out period exceeded” Error When Trying to See DB Hierarchies

I'm having problems with a database. I can run basic queries, albeit much slower than normal. When I attempt to view the hierarchy trees for tables, views, or procedures in SSMS Object Explorer, I ...
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2answers
671 views

SQL Server configuration / specification recommendations and advice!

I am about to deploy a new server at work as follows: Dell T610 2 x Xeon 2.53 Quad core 24 GB RAM 1 x Perc H700 RAID controller with 1GB Non Volatile memory 8 x 300GB 15k SAS Hard drives I am looking ...
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1answer
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Optimizing concurrent updates in Postgres

I'm running concurrent Postgres queries like this: UPDATE foo SET bar = bar + 1 WHERE baz = 1234 Each query affects the fixed K number of rows, and I can't find a way to enforce the order in which ...
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2answers
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Combine two event tables for multiple timelines into a single result set

This question is an extension to a question I've previously asked that was overly simplified. The more accurate example is demonstrated in this SQLFiddle, where I demonstrate a working (but slow) ...
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1answer
110 views

Sort by number of related rows in referencing table

Let there be two tables: Users id [pk] | name --------+--------- 1 | Alice 2 | Bob 3 | Charlie 4 | Dan Emails id | user_id | email ----+---------+------- 1 | 1 ...
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2answers
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Using Same CASE WHEN Conditions For Multiple Query Columns

Is there a "better" way to rewrite a SELECT clause where multiple columns use the same CASE WHEN conditions so that the conditions are only checked once? See the example below. SELECT CASE ...
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2answers
6k views

COUNT of rows with parent id equal to the row we have with a parent id of 0 in one query

I'd like to do the following in one query using MySQL: grab a row that has a parent_id of 0 grab a count of all the rows that have a parent_id of the row that we grabbed which has a parent_id of 0 ...
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4answers
19k views

TSQL command to delete backup files older than N hours

Can anyone please help me with a TSQL commmand to delete backup files older than N hours?
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1answer
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Difference between count(*) and count(1) in mysql?

In MySql we can count the total number of records by using count(1) or count(*). Is there any technical difference between them?
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1answer
4k views

How do I make MySQL auto increment in random order?

I have a table that contains several keys into other tables (where each key is comprised of multiple columns). I would like to create a new column for each key that would be an integer such that ...
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1answer
14k views

oracle format specifiers: to_number vs to_char

SQL> select TO_NUMBER(123.56,'999.9') from dual; select TO_NUMBER(123.56,'999.9') from dual * ERROR at line 1: ORA-01722: invalid number SQL> select TO_CHAR(123.56,'999.9') ...
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2answers
31k views

How can I dynamically alias columns?

I have a table (not designed by me) which has 20 variably named columns. That is, depending on what type of record you are looking at, the applicable name of the column can change. The possible ...
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2answers
8k views

Migrate all databases from one SQL Server 2005 to another

We have a production SQL Server 2005 server on which we are hosting 200 databases. We want to host these databases on our new server. On new server SQL Server 2005 is installed and is ready. I want ...
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1answer
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the <set clause>'s <multiple column assignment>

I just know a little sql basics and need to write a plain sql syntax highlighter/checker So I'm fighting through the standard... I stumbled over somthing I'm not sure I understand it right, as I never ...
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1answer
367 views

Grouping() equivalent in PostgreSQL?

I have a SQL query that runs in MS SQL Server and it has grouping(), rank() and rollup() functions / keywords in it. The query is given below. How can this be translated to PostgreSQL? select top ...
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2answers
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How can i return the max of a sum by each team?

I have a lot of teams and i want to know the maximum of sum total of each team. This's my query : SELECT campaign_id, campaign_identifier, team, campaign_name, Month(...