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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How do I read Query Cost, and is it always a percentage?

I'm currently studying for SQL 70-433 (the Microsoft Certification exam), and I'm getting very confused about the "query cost" performance metric. According to any documentation I could find via ...
14
votes
4answers
1k views

Is table aliasing a bad practice?

I remember learning to do this in a DBMS course for Master of Information Services students. To save yourself some typing, you can type: SELECT t1.id, t2.stuff FROM someTable t1 ...
11
votes
1answer
295 views

Why does subquery use parallelism and join doesn't?

Why does SQL server use parallelism when running this query which uses a subquery but it doesn't when using a join? The join version runs in serial and takes around 30 times longer to complete. Join ...
8
votes
3answers
6k views

Are individual queries faster than joins?

Conceptual question: Are individual queries faster than joins, or: Should I try to squeeze every info I want on the client side into one SELECT statement or just use as many as seems convenient? ...
8
votes
6answers
4k 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 ...
7
votes
2answers
957 views

How to find parent rows that have indentical sets of child rows?

Suppose I have structure like this: Recipes Table: RecipeID Name Description RecipeIngredients Table: RecipeID IngredientID Quantity UOM What are some good ways for ...
7
votes
4answers
2k views

Multiple operations using WITH

Is there a way to execute multiple operations using the WITH statement? Something like WITH T AS ( SELECT * FROM Tbl ) BEGIN OPEN P_OUTCURSOR FOR SELECT * FROM T; SELECT COUNT(*) INTO ...
6
votes
1answer
744 views

adding an order by to this query returns faster than without, why?

Any ideas on why adding a sort to this query returns considerably faster than without the order by? I would expect the opposite so what could make this happen? SELECT TOP (500) ...
5
votes
2answers
1k views

Slow ORDER BY with LIMIT

I have this query: SELECT * FROM location WHERE to_tsvector('simple',unaccent2("city")) @@ to_tsquery('simple',unaccent2('wroclaw')) order by displaycount I'm happy with it: "Sort ...
5
votes
1answer
2k views

Send email when certain Data is being inserted in MS SQL Server

I realize that there is an integrated email notification system in SQLServer, where I can configure it to send an email using my organization's Exchange server. I want to use that to send email on ...
5
votes
5answers
604 views

SQL Server Backup Process Tuning

I am working for a small company that has 20 full time web sites. And another 20-30 micro sites. We are having issues with the sites freezing every day after the SQL Server Agent backup is running. ...
5
votes
1answer
458 views

Dealing with temp tables when I have not control over db variables

I have no control over things like tmp_table_size and max_heap_table_size, and so as our tables grow the time taken by queries requiring temp tables is growing geometrically. I am wondering if there ...
4
votes
2answers
444 views

Order of columns in a compound index in PostgreSQL (and query order)

I have a table with 50K rows. It is actually a PostGIS table. The query has 4 parts (1 mandatory) (3 Optional) intersection box (a geography rectangle) with 4 lat,long (I use st_intersects) ...
4
votes
4answers
4k views

Executing a very large SQL file

I have a 830mb .sql file which is a scripted DB. I wish to execute this SQL so it will create and insert data into a database on a hosted server. I cannot get it to open in SQL Server Management ...
4
votes
1answer
7k views

Syntax of INNER JOIN nested inside OUTER JOIN vs. query results

TLDR; If you look at the 2 execution plans, is there an easy answer to which is better? I purposefully did NOT create indexes so it's easier to see what's happening. Following up on my previous ...
4
votes
1answer
15k views

temporary table inside procedure oracle

I'm in a situation right now. I'm migrating several procedures from Mysql 5.0 to Oracle 11g. Mysql procedures allow me to: 1. Create temporary tables 2. Insert data into temporary tables / Query these ...
4
votes
3answers
605 views

Full Text Search With PostgreSQL

i have a table with this rows: Stickers ------------------------------------------------------ ID | Title |Keywords (ts_vector) ------------------------------------------------------ ...
4
votes
1answer
443 views

How to Update same table on deletion in MYSQL?

In my Database I have a table: Employee with recursive association, an employee can be boss of other employee. Following is query I used to create table: CREATE TABLE IF NOT EXISTS `Employee` ...
4
votes
3answers
1k views

How can I write a proper query to JOIN all of these tables without duplicates?

Let's say I have four tables: TABLE: players COLUMNS: id, first_name, last_name TABLE: passing_stats COLUMNS: id, year, passing_yards (several other passing columns) TABLE: rushing_stats ...
4
votes
2answers
362 views

Running different instances of SQL Server from different networks on one box

I want to be able to run SQLSMS and select an instance to connect to but the instances are on different networks. I remotely log on to our server and from there, I want to be able to access our ...
4
votes
3answers
5k views

Stored procedure executes too long

We use SQL Server 2008. When I am watching in SQL Server Profiler I found some queries that take for example 20 seconds. The same query (in a stored procedure) when executed in SQL Server Management ...
3
votes
1answer
1k views

PostgreSQL list of integers separated by comma or integer array for performance?

As per subject, I have a field which is varchar in which i store some numbers separated by commas. The list grows and shrinks based on clients choices. I then use it in queries to check if a ...
3
votes
1answer
2k views

Moving postgresql data directory

I moved postgresql's data directory by following the following steps: Stop postgres cp -a source_data_directory destination_data_directory export PGDATA=destination_data_directory Changing data ...
3
votes
2answers
770 views

How to split a string to and get info from another table in mysql

I have a system to assign score for each sentence stored in a column: TABLE 1: word_scores word score this 3 is 4 a 5 test 1 another 0 sentence 8 TABLE 2: ...
2
votes
2answers
71 views

Call UPSERT function multiple times to different inputs

I have a function: merge_vehicles(vid, cid, vname, reg_no, name, name_1st) Can i call it multiple times on inputs like (2335, 55, '246BDH', '246BDH', '811', 1), (2336, 55, '038THX', '038THX', ...
2
votes
1answer
154 views

Select data based on records created_at column

I have two tables Keywords, ProjectReports: http://sqlfiddle.com/#!15/06ae3/1 As you can see in that example everything works fine, but I want to get more data from those 2 tables and I don't know ...
2
votes
2answers
522 views

Speed up bulkinsert on sql server

We're doing some testing and this involves adding 10.000 rows every 10seconds in a table that has 4 int columns and one of them is clustered index. When we run the app the first bulkcopy takes around ...
2
votes
2answers
425 views

Optimize simple query using ORDER BY date and text

I have a query to a table in Postgres with an order based on a date field and a number field, this table has 1000000 records The data types of the table are: fcv_id = serial fcv_fecha_comprobante = ...
2
votes
3answers
3k views

In Microsoft SQL Server 2008, syntax generates the error “The Parallel Data Warehouse (PDW) features are not enabled.”

I have the following virtual column generated from an aggregate over a sorted partition, MIN(picture_id) OVER ( PARTITION BY [360_set] ORDER BY picture_id ASC ) However, when I execute that, I get ...
2
votes
1answer
7k views

Multiple “GROUP_CONCAT”s with WHERE clause

In a table as id name type info 1 BMW car yes 2 Reno car no 3 IBM electronics no 4 Sony electronics yes 5 Mazda ...
2
votes
1answer
363 views

Restriction on self referencing on insert in MYSQL?

How to restrict insert on adding self referencing rows in a recursive relation table (a table contains foreign key points itself). mysql> SELECT * FROM Employee; ...
2
votes
2answers
2k views

Querying a database efficiently for a huge chunk of data

Here is my query SELECT * FROM ( SELECT a.*, rownum rnum FROM ( SELECT id, data FROM t ORDER BY id ) a ...
2
votes
2answers
2k views

CREATE INDEX for long columns

I am looking for alternative to create index on long column: create table line ( field_key integer not null, value varchar(4000), ... ); create index key_value_idx on line ...
2
votes
1answer
370 views

Is staggering reindexing jobs a good strategy?

I have inherited a server with 35 databases and a job that reindexes all tables on all databases (using sp_MSForEachTable). It's taking over 14 hours to complete and is now blocking other processes. ...
2
votes
1answer
419 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 ...
2
votes
2answers
400 views

Check Index Fragementation Query

I'm completely stumped. I'm a relatively new SQL Server DBA so I'm at a loss with the following situation; hoping maybe someone had an idea. I have a new production SQL Server (Windows Server ...
1
vote
1answer
74 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 ...
1
vote
1answer
202 views

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 ...
1
vote
1answer
2k 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 ...
1
vote
1answer
1k 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 ...
1
vote
1answer
203 views

SQL from/where or join?

I was wondering performance wise what would be faster a join or a from and where query. I am trying merge and update query but performance is terrible?
1
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3answers
1k views

sql server 2008 - controlling size of log file

I am getting this error. Msg 9002, Level 17, State 4, Line 2 The transaction log for database 'SalesDWH' is full. To find out why space in the log cannot be reused, see the log_reuse_wait_desc ...
0
votes
3answers
43 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 ...
0
votes
1answer
111 views

Select post and concatenating all categories it belongs to

I have 3 DB tables POSTS +----------+----------+----------+ | id | title | content | +----------+----------+----------+ CATEGORIES +----------+----------+ | id | title | ...
0
votes
1answer
112 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 ...
10
votes
1answer
12k 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 ...
10
votes
1answer
7k 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 ...
9
votes
2answers
3k 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 ...
8
votes
2answers
1k 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 ...
8
votes
6answers
2k 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 ...