DO NOT USE this for questions targeting Microsoft SQL Server, use the tag sql-server instead. "SQL" is an acronym for "Structured Query Language", it is used in relational database management systems (RDBMS) to query, update, delete, and insert data as well as modify the structure of the database. ...

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2answers
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Subqueries' aliases same as main queries' aliases

I have an SQL query whose aliases are the same as some of its subquery's aliases. For example: select * from ROOM r where ... ( select * from ROAD r ...
9
votes
2answers
8k views

Efficient query to get greatest value per group from big table

Given the table: Column | Type id | integer latitude | numeric(9,6) longitude | numeric(9,6) ...
9
votes
2answers
4k views

foreign key constraint violation issue

I have identified 3 situations. A student with no enrollments. A student with enrollments but no grades. A student with enrollments and grades. There is a trigger on the enrollments table to ...
9
votes
2answers
4k 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 ...
9
votes
2answers
3k views

SQL Server's READ COMMITTED SNAPSHOT vs SNAPSHOT

I was researching the differences between SQL Server's READ COMMITTED SNAPSHOT and SNAPSHOT isolation levels and came across the following resource: Choosing Row Versioning-based Isolation Levels ...
9
votes
2answers
10k views

Slow Performance Inserting Few Rows Into Huge Table

We have a process that takes data from stores and updates a company-wide inventory table. This table has rows for every store by date and by item. At customers with many stores, this table can get ...
9
votes
5answers
547 views

Efficiently Filter Large Set With Disjunctions

Let's say I have a single table CREATE TABLE Ticket ( TicketId int NOT NULL, InsertDateTime datetime NOT NULL, SiteId int NOT NULL, StatusId tinyint NOT NULL, AssignedId int NULL, ...
9
votes
2answers
2k views

Treating certain Arabic characters as identical

In Arabic we have characters like ا (alef) and أ (alef with hamza). Users write them interchangeably and we want to search them interchangeably. SQL Server treats them as separate characters. How ...
9
votes
5answers
4k views

Group By hour over large dataset

Using MS SQL 2008 I am selecting an averaged field from 2.5 million records. Each record represents one second. MyField is an hourly average of those 1 second records. Of course the server CPU hits ...
9
votes
0answers
4k views

Fast SQL query with * but extremely slow with specific columns? [closed]

We have a query that we're running on SQL Server 2008 in the Management Studio. I can't give the exact query details, but let's say it's equivalent to this: SELECT * FROM MyView a (nolock) INNER ...
8
votes
5answers
3k views

Why is the SELECT clause listed first? [closed]

I'm not sure if this question is on-topic - if not, feel free to close. Also, if it'd be a better question for another StackExchange site, I can ask it elsewhere. I was wondering why SQL places the ...
8
votes
3answers
1k views

SQL Database Structure for RESTful API

I am creating a RESTful API. I am struggling to decide on the best way to design my database tables around my resources. Initially, I though a table per resource would be a good way to go, but I'm ...
8
votes
3answers
3k views

Does disconnecting the network stop a query?

I recently executed an update query against 100,000 records. I realized I'd made a mistake while the query was running and quickly unplugged the network cable. Does the update query stop ...
8
votes
3answers
987 views

SQLITE: A problem of tags and products

I'm searching for a way to create a query to do the following: Let's consider 3 tables: products: List of products tags: list of tags tag_ties: table used to associate a tag to a product Let's ...
8
votes
6answers
426 views

Backing up SQL DB more frequently

I currently have a scheduled task that fires off each night at 2 AM that calls SQLCMD.exe and passes it a .sql script to run for the backup (shown below). We're a pretty small company with growing ...
8
votes
5answers
3k views

Query Running Differently on SQL 2005 vs SQL 2008R2

At my office, we have a query that is pretty ugly, but runs pretty well in production and in the development environment (20sec, and 4sec respectively). However in our testing environment it takes ...
8
votes
6answers
5k views

Find “n” consecutive free numbers from table

I have some table with numbers like this (status is either FREE or ASSIGNED) id_set number status ----------------------- 1 000001 ASSIGNED 1 000002 FREE 1 000003 ...
8
votes
2answers
11k views

How do I show the binlog_format on a MySQL server?

How do I show the binlog_format on a MySQL server? And if I dont like it how do I set it to XX permanently? Where XX is STATEMENT, ROW or MIXED.
8
votes
2answers
35k views

Returning a result set with multiple rows based on max date

I have a child table that is something like this: [Cust Date Table] | Customer ID | Some Date | Balance | +-------------+------------+---------+ | 1 | 2012-04-30 | 20.00 | | 1 ...
8
votes
5answers
4k views

Oracle sort varchar2 column with special characters last

How can I sort in Oracle a Varchar2 or NVarchar2 column to be in my own custom defined order. Or are any existing options available that will put letters first, then numbers, then all special ...
8
votes
6answers
3k 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 ...
8
votes
3answers
767 views

Worse performance on a new server

We've been on a dedicated server (single quad-core, 6 GB RAM) and are moving to a new dedicated server (2x hex-core, 32 GB RAM). Both are Windows Server 2008, SQL Server 2008. The performance on the ...
8
votes
4answers
178 views

SQL Server 2005/8 Query Optimisation Hints

I'm looking at educating a team on writing better SQL Server queries and was wondering what people's best hints were for improving performance. For instance I once had a DBA who insisted that ...
8
votes
2answers
233 views

Are “out of the row” fields read when a clustered index is used?

I know that when VARCHAR(MAX)/NVARCHAR(MAX) columns are used the data is stored out of the row - the data row will have a pointer to another location where the 'large value' is stored. I have the ...
8
votes
4answers
2k views

How to check if a subquery has exactly one distinct result and a specified value concisely?

I found myself writing the following: select 'yes' where exists(select * from foo where val=1) and not exists(select * from foo where val<>1); and wondering if there is a more concise way ...
8
votes
3answers
19k views

How to do a case sensitive search in WHERE clause?

I want case sensitive search in SQL query. But by default, MySQL does not consider the case of the strings. Any idea on how to do a case sensitive search in SQL query?
8
votes
4answers
11k views

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 ...
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votes
3answers
2k views

SQL Server - Multiple running totals

I've got a base table with transactions and I need to create a table with running totals. I need them to be per account and and also have a few running totals for each account (depending on the ...
8
votes
3answers
3k views

Is there a standard implementation of a Users Database?

I need to implement basic personalized user functionality for my website. Is there a standard structure for databases of this type? Like is it common practice to have all user info and data in a ...
8
votes
4answers
959 views

overstating field size in database design

I have some fields for my tables that are strings and at the moment, most of the field size have pretty high character limits. For instance, 100 char for the street name. Is there a penalty for using ...
8
votes
2answers
193 views

Non-Clustered Indexes - keys and nonkeys

I just want to make sure I'm on the right track with these concepts, so any feedback would be greatly appreciated. Here's my theory from the query I've just optimised, through a process of trial and ...
8
votes
2answers
370 views

Do agile software development approaches apply to SQL?

I would like to learn if agile software development methods/principles/patterns are valid to SQL programming as well. If yes, where would be a good place to start learning about that? Are there any ...
8
votes
3answers
6k views

How to Best Implement nearest neighbour search in mysql?

So, in short, What should be the data type of latitude and longitude? What SQL command I should call to get the first 100 nearest restaurants for example? Detail: I have 100k biz record each with ...
8
votes
3answers
2k views

What are the alternatives for an ORDER BY clause in a View?

This question just had to be in this site :) ORDER BY is forbidden to use in a view, as I understood because of the possibility for multiple order by's when using this view. I know that there are ...
8
votes
3answers
3k views

Oracle: How do I query a Hierarchical table?

Background This is for the construction of some views we'll be using for reporting. I have an table of locations, the key fields being "location" and "parent". The structure that these two fields ...
8
votes
3answers
2k views

Deleting all duplicates

I am trying to delete all the duplicates but keeping single record only (shorter id). Following query deletes duplicates but take lot of iterations to delete all copies and keeping original ones. ...
8
votes
4answers
2k views

How can I optimize this MySQL query further?

I have a query that is taking a particularly long time to run (15+ seconds) and it is only getting worse with time as my dataset grows. I have optimized this in the past, and have added indices, ...
8
votes
5answers
210 views

What is the best way to find out how many records do not have a proper phone number in SQL Server?

I have a field that people historically could use to freely supply a value. I need to identify the records which do not have an appropriate value so I can clean them. I've been looking around in SSIS ...
8
votes
2answers
593 views

function hangs with null case operation

I created a function that accepts a start and end date, with the end date being optional. I then wrote a CASE in the filter to use the start date if no end date is passed. CASE WHEN @dateEnd IS NULL ...
8
votes
3answers
5k views

How to boost performance of virgin queries in MS SQL Server?

I have ASP.NET web site that does it's own independent caching of data and data does not change for long periods of time, so it does not need to query SQL Server second time with same query. I need to ...
8
votes
3answers
2k views

Is there a way to programmatically script all objects associated with a given table?

I know that in SQL management studio I can right click a table/trigger/key and script object as.... Is there a way to do this programmatically, given an object's name? If so, is there a way to find ...
8
votes
1answer
421 views

Why is SELECT * much faster than selecting all columns (in a different column order) by name?

On a table with columns a,b,c,d,e,f,g,h,i,j,k I get: select * from misty order by a limit 25; Time: 302.068 ms And: select c,b,j,k,a,d,i,g,f,e,h from misty order by a limit 25; Time: 1258.451 ms ...
8
votes
1answer
778 views

Deleting large amounts (4 million rows) of mysql data efficiently, on a very regular basis

We have a mysql table that at any given time has about 12 million rows. We need to delete old data to keep the size of the table somewhat manageable. Right now we are running this query daily, at ...
8
votes
5answers
833 views

SQL Server 2008 and extended properties [closed]

In SQL Server, what do you guys use extended properties for? Some articles and blogs are suggesting they be used for self-documentation of the database and its objects but I can't see this being used ...
8
votes
3answers
6k views

When should indexes be dropped and recreated?

We are constructing a data warehouse that initially will be 1 TB and will grow around 20gigs every month. For certain tables we are doing daily ETL processes and others we are doing weekly/monthly. ...
8
votes
2answers
4k views

How to retrieve foreign key constraints data

I'm looking for a query allowing to retrieve foreign key infos (each line: referrencing table & field, referrenced table & field) of an entire schema. I've found this, but does not gives all ...
8
votes
2answers
2k views

How to delete a procedure which name is ambigous?

I am using informix... I dont know how i did it, but there are two procedures with the same name in my database. When i try to remove them with a DROP PROCEDURE myProc; then i get a error message ...
8
votes
1answer
2k views

Deadlock when update different rows with non-clustered index

I'm solving a deadlocking issue while I noticed the lock behavior is different when I use clustered and non-clustered index on the id field. The deadlock issue seems to be solved if clusted index or ...
8
votes
5answers
7k views

Use of HAVING without GROUP BY in SQL queries

In order to use HAVING in SQL queries , must there be a GROUP BY to aggregate the column names? Are there any special cases where it is possible to use HAVING without a GROUP BY in SQL queries? ...
8
votes
1answer
881 views

IO_STALL question and understanding

I am collecting IO_STALLS from sys.dm_io_virtual_file_stats every 5minutes and then doing a delta to see which files are being affected most by IO. In one 5min period I get a delta of 5826331 ms ...