An acronym for "Structured Query Language" (it's not the name of a specific DBMS product), SQL can be used in relational database management systems (RDBMS) to query, update, delete, and insert data as well as modify the structure of the database. It can also be used to manage schemas and data ...

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Figuring out database timezone

Does anybody know of a way to alter a time zone on a SQL database? Is there any tool that could find the objects using the date and time?
3
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2answers
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Can the sorting from an ORDER BY statement be saved explicitly with only one UPDATE statement?

I have this table: SELECT * FROM items id | item | position ---|-----------|---------- 1 | USB cable | 0 2 | SD card | 4 3 | Mouse | 2 4 | Keyboard | 0 5 ...
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6answers
508 views

Check if DISTINCT is really necessary

I have a query in mysql as follows. SELECT DISTINCT `tableA`.`ColA`, `tableA`.`ColB`, `tableB`.`ColA`, ... FROM `tableA` LEFT JOIN `tableB` ON `tableA`.`colC` = `tableB`.`colA` WHERE ...
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3answers
13k views

Notification on long-running query or deadlock in SQL Server 2008 R2?

I'd like to know if there is a way to send a notification on deadlock? If so what queries would be required. I understand that SQL Server takes care of deadlocks, I simply would like information on ...
2
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2answers
425 views

Full Name search query

We currently have a solution for this in production, but it's pretty bad. I'd like a fresh perspective on it please. We have a PERSON table with an ID, LAST_NAME, FIRST_NAME, MIDDLE_NAME, and ...
4
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1answer
538 views

T-sql: Select most specific match from table

Apologies for the horrible title. I couldn't come up with a better way to briefly describe the problem. Here's the scenario: Users can set up service instructions to be attached to a work order ...
2
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1answer
5k views

How to display a number with fixed number of digits before the decimal?

I am looking for result 0123.56 and the following query should have worked. SQL> select to_number(123.56,'0999.99') from dual; select to_number(123.56,'0999.99') from dual * ERROR ...
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1answer
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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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5answers
575 views

EXISTS clause in SQL

I have following requirement: main_set table has all the ids, user_input table has all user entered ids. I want result of ids that exist in user_input table. If nothing in user_input table then I ...
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1answer
263 views

Optimising a sql correlated subquery statement

I am updating a column on tableA with data from tableB like this: update tableA set bKey = select bKey from tableB B where B.colB = tableA.colB bKey has a unique index on tableB. Which is the ...
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3answers
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Query Performance Tuning

When you finish writing a query/stored proc/function, what's the most informative way to quickly get some performance parameters? Do you run the query and view the actual execution plan? If so, what ...
1
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4answers
274 views

Is there a DBMS that allows the “= NULL” syntax?

Inspired by a StackOverflow question (Why doesn't SQL support "= null" instead of "is null"?). Is there a DBMS that actually supports the = NULL syntax?
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3answers
285 views

Non-deterministic aggregated result

Why is my query non-deterministic? I have query that do the following: select sum(float1*float2*coalesce(float3,1)) from table When I run this query I get a deterministic result, but it seems not ...
4
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0answers
160 views

Which SQL datatypes exist since when and in which RDBMS? [closed]

I found a general comparision of different SQL implementations that only covers some data types (BOOLEAN and TIMESTAMP) and a comparision of datat type support in different RDBMS from 2009 that does ...
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5answers
807 views

Advice with date column SQL Server 2005

I have two datetime columns in SQL Server 2005 that I need to query without the time portion of the datetime. Currently, my query looks something resembling this (just an example): WITH Dates AS ( ...
4
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1answer
699 views

How to get text for default language

I have so tables: and so data at Language table: and so data at Text table: I have to return text for requested language if it exists and text for default language if it does not exist. Is it ...
4
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3answers
354 views

Database Design Issues

My question consists of three parts: When can I be sure that my database design is perfect? Is returning to the database design to change some issues (i.e, adding new column, deleting a column, ...
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2answers
2k views

PostgreSQL: Using schema and table names from other tables?

Consider the situation where I have all my schema names in one table and all my table names in another table. Is it possible to do something like in the following? SELECT value FROM (SELECT ...
8
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3answers
752 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 ...
2
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2answers
1k views

How do I group results in batches of consecutive rows with the same 'module'

I'm looking for a seemingly very simple SELECT. I have a logging table LOGGING of which three columns are of interest to me: MODULE (text), PDATE (date), PTEXT (text). Actually, I care only about ...
4
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2answers
1k views

Estimate average and median efficiently in Postgres?

I have a Postgres database with tables in the billion scale. So any aggregate functions such as count() and avg(), as well as "order by random()" are very time consuming. Postgres has pg_catalog which ...
6
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4answers
251 views

Which SQL standard is most broadly and completely supported?

I want to concentrate on one of the SQL language specs for learning and reference purposes. Which version of the SQL standard is most broadly supported across DBMS'es so that I can focus my time and ...
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3answers
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when selecting from multiple tables I get a multiplication of the records

When executing this query below it takes too long. And the result is too much records, more than possibly in the database. The query should return around 117.000 records. That is the amount of ...
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3answers
62 views

SQL Server - Index Including PK

Lets assume we have a table as follows: PK -- nonclustered primary key Col1 -- unique clustered Col2 Col3 Is this index: nonclustered index on (Col2, Col3) any different from this index: ...
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3answers
658 views

Improving slow queries. Slow query log attached

Below is the Slow Query Log when my .NET application was running. Please let me know how to improve the performance of the queries: TCP Port: 3306, Named Pipe: (null) Time Id Command ...
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1answer
66 views

SQL query question

I want to find the records of August birthdays in own table.I'm using Datetime Field. Sample record: 01.08.2001 06.06.1985 26.08.1995 etc.. How should I do write a query? Regards,
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1answer
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SQL Server CTE problem

This question is in reference to my last question: SQL Server 08: Union over while I'm writing a CTE to do what was described in that question (find available time slots over a given number of days. ...
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1answer
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How do I convert this Access query for SQL Server? [closed]

I have a Query used in Access which does not work in SQL Server as it stands: SELECT mstPatient.PatientID, mstPatient.PatientID AS PKNO, ...
2
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1answer
382 views

SQL Server 08: Union over while

I've done some reading on this, and I keep seeing people say it's a bad idea, but hear me out! I have a stored procedure which needs to find a series of timeslots over a number of days. Due to the ...
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3answers
4k views

Performance difference for COALESCE versus ISNULL?

I've seen a lot of people use the COALESCE function in place of ISNULL. From internet searches, I've found that COALESCE is ANSI standard, so there is an advantage that we know what to expect when ...
12
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1answer
868 views

What does collation mean in database parlance?

I am learning sqlite from a book which has mentioned collation and collating sequence multiple times. What does it mean exactly in the database world ?
1
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1answer
478 views

IS_SRVROLEMEMBER returning NULL for valid non windows user

I have a service that executes a stored procedure to query the db for results. The stored procedure needs to use impersonation on the user who is logged in the client (since the service has its own ...
4
votes
2answers
1k views

Best way to evenly distribute data over partitioned tables

I am working with a database with roughly around 500MM records. We currently use a static partitioning method that partitions the data by an int identifier such at < 150MM goes on partition 1, > ...
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2answers
173 views

MySQL Query Optimization : Bets and Averages

I have the following selection string: SELECT * , AVG( `q1` ) AS betavg, COUNT( bet_id ) AS nr, MAX( q1 ) AS qmax, (MAX( q1 ) - AVG( `q1` )) AS diff FROM jos_bet_1x3_best GROUP BY `bet_id` HAVING ( ...
1
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1answer
111 views

I need help migrating data through databases

i've a web page with some data about the users. Recently I made a complete change and start developing a new portal and of course a new DB structure. My question is what's the best way to migrate my ...
7
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3answers
4k 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 ...
4
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3answers
1k views

MySQL Query Optimization : Indexing and Pagination

I'm adding pagination to my 'latest news' php script and running in to an issue. SELECT sid, title, time, bodytext, author, url FROM news WHERE approved=1 ORDER BY time desc LIMIT $start, $limit I ...
2
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2answers
587 views

Slow Query logging everything

I have a mysql instance that is logging slow queries. I have it set to 1 sec, but I am getting back lots of these:(example) Query_time: 0.000237 Lock_time: 0.000064 Rows_sent: 0 Rows_examined: ...
3
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1answer
516 views

A question on MySQL SELECT Algorithm/Function

Let's say I have 100,000 rows in a table, and each of the rows has a boolean value. Only ten of these rows have a value of 1, the rest are 0. How would MySQL perform a SELECT on only the rows with a ...
6
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3answers
231 views

Find material for improvement in Microsoft BI

Which websites, books etc. can you recommend me to improve my basic knowledge in Microsoft Business Intelligence 2008, SSAS, SSIS and SSRS? Please remember that I'm a newbie in technical BI tool. If ...
6
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2answers
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How to use variables inside a select (SQL Server)?

If I want to compute a column and use the result in more than 1 column, how do I do this without making the computing twice? Example: SELECT LOWER(SUBSTRING([NAME], 4, 100)) + '@somedomain.com' as ...
6
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2answers
2k views

'Conversion failed' error with ORDER BY CASE expression

I have the following Stored Procedure that works great EXCEPT when I set the 'OrderBy' to 'OrderNumber'. I get the following error: Conversion failed when converting the nvarchar value 'SK11270' to ...
61
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4answers
9k views

Why use both TRUNCATE and DROP?

In the system I work on there are a lot of stored procedures and SQL scripts that make use of temporary tables. After using these tables it's good practice to drop them. Many of my colleagues (almost ...
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1answer
2k views

How to get query execution time and query result at the same time? [closed]

Is there any SQL query syntax that returns query execution time and query result at the same time?
2
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1answer
858 views

Can't retrieve data of countries and regions

Goal: Improve my sql ability by doing some coding and reviewing existing code. Problem: I have spent lots of hour to find a solution based of this question "3c. Some countries have populations more ...
3
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3answers
606 views

ts_rank massively slows my query, how can I improve performance?

Here's the table definition Table "public.kb_article_contents" Column | Type | Modifiers ------------+----------+----------- article_id | smallint | not null contents | text | not ...
10
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4answers
34k views

Can I see Historical Queries run on a SQL Server database?

Someone was running a query on our SQL Server database remotely and their system crashed. They have no backup of that query and want to see what was run on the server. Is it possible to find this ...
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2answers
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Prevent copying to temp table (sql)

I have two tables - comments and votes : comments(id, text, user_id, page_id) votes(id, value) There are 2,000,000 rows in the votes table. I created the following query: SELECT ...
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3answers
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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 ...
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2answers
84 views

Model of database management systems

Having just installed MYSQL server and client on my laptop with Ubuntu, I was wondering, (1) do all database management systems use the server-client model, regardless of whether they are actually ...