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

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type recognition with MonetDB, *create* tables from CSVs

I am confused whether you can copy records into a new table in MonetDB. The official documentation seems to talk only about copying into existing tables. I have quite a large universe of billions of ...
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1answer
4k views

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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1answer
3k views

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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1answer
577 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
375 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
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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3answers
143 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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1answer
312 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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1answer
1k views

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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2answers
1k views

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
152 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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1answer
75 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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1answer
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What is the Difference between SQL Server 2008R2 and SQL Server 2014?

I want to take my project from SQL Server 2008 R2 to SQL Server 2014. But I want to learn what is T-SQL the difference between 2008 R2 and 2014 for Database Engine? I mean is there any end of life ...
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2answers
11k views

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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1answer
20k 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
2k views

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
5k views

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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6answers
4k views

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 ...
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1answer
3k views

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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5answers
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Database design: Dividing multiple identical tables, good or bad?

I am very new at SQL and databases in general. I only use them for the occasional homework so I haven't even tried to master them. I have seats at a theater, the seats are divided into 4 main areas ...
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2answers
394 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 ...
7
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1answer
296 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
2k views

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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4answers
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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
2k views

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
6k views

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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2answers
61 views

generate_series for multiple record types in postgresql

I have two tables that I want to query: pest_counts and pests which look like: pests id | name ---+-------------- 1 | Thrip 2 | Fungus Gnats pest_counts id | pest_id | date | count ...
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4answers
4k views

Checking if 2 tables ( on different servers ) have the same exact data

So it seems that the company who is hosting our SQL Servers has been having some trouble with the replication from the production server to the backup server... I believe some of the tables have been ...
6
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7answers
898 views

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
1k views

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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2answers
67 views

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) ...
5
votes
1answer
1k views

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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1answer
4k views

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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2answers
29k views

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
647 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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2answers
81 views

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, ...
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2answers
151 views

Get the last 5 distinct values for each ID

I'm working with PostgreSQL 9.4. I have a table that contains the following entries: id | postcode | date_created ---+----------+----------------- 14 | al2 2qp | 2015-09-23 14:46:57 14 | al2 ...
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2answers
119 views

Use column values in ORDER BY and LIMIT clauses

I have this table in a Postgres 9.3 database: I need to use the content of columns order and limit to sort and filter this table. The table will be sorted by column first_name. The final result ...
4
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2answers
6k 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
1k views

Do SQL Server Views update their data types automatically based on what tables feed them?

Someone mistakenly created a bunch of nchar fields in database tables. I noticed this, and after examining the issue, we're moving these fields to nvarchar types and trimming the values inside. In my ...
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1answer
2k views

SQL Server 2008 R2 Upgrade (Express to Standard) fails. No “Select Instance”

Hello there, i got stuck in the progress of upgrading 3 systems from SQL Server 2008 R2 Express Edition --> SQL Server 2008 R2 Standard Edition Problem: The Option "Select Instance" in the ...
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2answers
5k 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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2answers
2k views

SQL Server 2012 database backup successfully report but no backup file

I have created maintenance plan in SQL Server 2012. And every day, the maintenance plan should backup the database. There is no database backup file when I look in the folder where the backups must ...
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3answers
25k views

“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 ...
4
votes
2answers
218 views

Checking a wide table for nulls [duplicate]

Possible Duplicate: Test if any fields are NULL I am new here. I have a table with 70-odd columns. Is there a way I can check the number of rows with at least one null value in any column ...
4
votes
3answers
8k views

Why so many logical reads?

I have a very simple query that is showing in Activity monitor and other statistics as having the most logical reads on my entire DB server. SELECT MAX(RESULT_DATE) FROM TABLEX mm WITH (NOLOCK) JOIN ...
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1answer
12k 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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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 ...
3
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3answers
146 views

Choosing a PK: VARCHAR(2) or SMALLINT(2)?

Today we were discussing the following: Brazil has 27 states and each one has its own abbreviation (just like USA). So we've got RJ for Rio de Janeiro, SP for São Paulo, MG for Minas Gerais and so ...
3
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1answer
38 views

How to get 0 as array_length() result when there are no elements

I have a query like this: select id, array_length(users_who_like_ids,1) as ct from queryables order by 2 desc; But empty arrays (with no elements) sort on top. I'd rather have array_length() return ...