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. ...

learn more… | top users | synonyms (1)

2
votes
1answer
10k 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 ...
5
votes
1answer
169 views

Practical application of EXISTS vs. LEFT JOIN to find addresses for delivery

Our end users have many ways of shipping product to our customers. They can use the customer address in one table ([customer]), a specific delivery address in another ([dropship]), or yet another ...
0
votes
2answers
810 views

How to mix pairs of rows without JOIN (in a temporary table)?

I have a TEMPORARY table containing pairs of key/value as id col1 col2 type pair 1 key1 key2 key 1 2 value1 value2 value 1 3 key3 ...
0
votes
1answer
682 views

Optimising MySQL query with lots of self-joins

I have an entity_relationship table that describes relationships between entities. Each relationship will have 2+ entities involved. In some cases it can be said that one entity is a constituent of a ...
0
votes
2answers
825 views

how to select * from XML where id=1?

declare @xml xml, declare @num int set @num = 1 set @xml = ' <row> <Id>1</Id> <name>reza</name> </row> <row> <Id>2</Id> ...
3
votes
2answers
210 views

Query taking too much time

My query is taking too much time to execute. Please help me here. mysql> explain select pcm.catalog_id from cat_produ_catal_map_defer pcm, cat_catal_catal_map_defer ccm, cat_catal_defer c ...
1
vote
1answer
151 views

Transposing data

I have a table with 31 columns which contain values for each day in a month and I want to create a tranpose table like the example below. Real data in the database is really big so I don't expect to ...
3
votes
1answer
232 views

Bayesian ranking

I have the following table in my database: ╔════════╦═════════════╦═══════════════╗ ║ Name ║ total_stars ║ total_reviews ║ ╠════════╬═════════════╬═══════════════╣ ║ Item A ║ 27 ║ ...
3
votes
1answer
3k views

How to re-assign two variables in a conditional UPDATE

Consider a simple update as SET @var1 = 20; SET @var2 = 26; UPDATE table1 SET col1=IF(@var1>50, @var1 := @var1-col4, @var1 := @var1+col5), col2=IF(@var2>50, @var2 := @var2-col6, @var2); ...
5
votes
3answers
2k views

“AT TIME ZONE” with zone name PostgreSQL bug?

I was answering this stackoverflow question and found strange result: select * from pg_timezone_names where name = 'Europe/Berlin' ; name | abbrev | utc_offset | is_dst ...
1
vote
1answer
358 views

How to re-arrange rows to best fit within groups?

I categorized a table with the method introduced here to categorize my items to folders with a limit size of 100. mixing_order id num_items cat order_in_cat cumulative_sum folder 1 ...
4
votes
1answer
344 views

Specifying the node to connect in db2

I have 2 nodes in my db2 catalog. How would I include the node on which I want to connect inside the db2 connect paramters? Node 1 entry: Node name = DB2HOST1 Comment ...
3
votes
3answers
1k views

How to delete large amount of data from a sql table?

We ran out of disk space and we have a table with about 10million records. We'd like to delete the old records which are about 2million. What are the impact of just deleting these using a simple ...
4
votes
1answer
465 views

Why does WAITFOR (RECEIVE FROM QUEUE) show up in the monitor incorrectly?

I kick off the following command in my app: WAITFOR (RECEIVE CONVERT(int, message_body) AS Message FROM MyQueue) When I run `sp_who2 active', I get Status=SUSPENDED and Command=DELETE Note: ...
13
votes
2answers
410 views

Does firing off an indefinite WAITFOR increase the log file size?

In the last release of my app, I added a command that tells it to wait when something arrives in the Service Broker queue: WAITFOR (RECEIVE CONVERT(int, message_body) AS Message FROM MyQueue) The ...
-1
votes
2answers
430 views

Oracle SQL Query/SubQuery Single column with mutilple data [closed]

Id File-Name Descrption 1 yyyy Started 2 yyyy incompleted 3 rrrr Started 4 tttt started 5 uuuu started 6 rrrr completed 7 tttt completed 8 uuuu ...
3
votes
1answer
469 views

How to categorize rows by SUM of a column in mysql?

I have a table as id num_items folder 1 4 2 33 3 74 4 41 5 24 6 34 7 46 8 55 9 11 I want to assign folder number to rows but limiting the number of items in each folder (e.g. ...
1
vote
1answer
248 views

MapReduce performance on a single PC [closed]

I have heard that Hadoop has better performance than MySQL. Until now, I have used relational databases so this is really new technology for me. I have a 6 core PC. Suppose I have a table with 20 ...
1
vote
0answers
349 views

big mysql database optimization

My Joomla mysql database has about 3.4 million rows in content table. It is just static article. Very slow and often use out of resources. To speed up it, I segmented it into 6 sub-tables and added ...
1
vote
2answers
385 views

Automatic create SQL database and table relationship

For SQL Server 2008, what is the best way to automatically "draw up" the Database relation ship and table relationship too? Is there any way to visualize database with this.
2
votes
2answers
558 views

Combining two similar SQL queries

I'm using the following SQL query twice with different values of limit. In my case, 40 and 100, though it doesn't really matter. My question is - can I combine these two queries into one query? It ...
0
votes
1answer
3k views

How to UPDATE a column to SET previous row value to NULL cells?

I have a table as id value 1 music 2 3 movie 4 5 6 book 7 8 Some values are missing, and I want to assign the value of previous row to produce id value 1 music 2 music 3 movie 4 ...
1
vote
1answer
109 views

How to aggregate datapoints in a table?

Suppose I have following table - CREATE TABLE data_points (t DATETIME PRIMARY KEY, value INTEGER); I want to aggregate the data by calculating average of every 10 points in the table. i.e. If ...
0
votes
1answer
133 views

clustered index - data warehouse

My source data comes from multiple OLTP databases where the primary key is an identitiy column. We anticipate adding data centers and/or splitting the databases by product. Currently i have one system ...
3
votes
1answer
1k views

Profiler TextData output is null

I am doing a trace on a database and dumping the trace realtime into a table. The reason I'm doing a trace is I want to see all the queries that are being executed against the database. ...
2
votes
2answers
934 views

How to GROUP_CONCAT between given rows?

I have a table as id diary 1 breakfast 2 walk 3 start 4 office works 5 office projects 6 end 7 taxi 8 start 9 preparing for meeting 10 doing the meeting 11 end 12 night I want ...
0
votes
1answer
233 views

avoid insert xml duplicate data

how can to prevent duplicate inserts for every Execute? insert into IQ (XMLDT)values('<row>sdsdf</row>')
6
votes
1answer
981 views

ANSI/ISO plans for LIMIT standardization?

Are there currently plans to standardize one best way of limiting the number of results returned by a query? The stack overflow question at Is there an ANSI SQL alternative to the MYSQL LIMIT ...
1
vote
1answer
1k views

Splitting a column to normalized table

I have a de-normalized table as Original De-Normalized Table id text 23 first,second|third,fourth,fifth|sixth I want to normalize the database to create the following tables Table 1: (Split by ...
3
votes
2answers
10k views

How to Drop Database in Single_User Mode

How do I drop a database which shows DatabaseName (Single User) as its name? When I try to delete it, I get the following error: Alter failed for Database 'DatabaseName'. ...
0
votes
2answers
478 views

Merging multiple databases as separate schemas in PostgreSQL

I have to combine data from 4 different databases. Each having its own design. What i want to do is to Create a new database with my desired schema. and one schema per (to be merged) database Then ...
1
vote
3answers
557 views

Which RDBMS has the most advanced “table-valued” functions?

Every Database Management System focuses on specific features and applications. I am using mysql, probably as it is popular and satisfies common needs. However, I came across a problem, which needs ...
2
votes
2answers
610 views

Reordering data in a table

I have a table that stores sensor data (in SQLite) and looks like this; TABLE Timestream: idTimestream PK autoincrementing integer, time int not null, value float not null, idSensor integer not ...
3
votes
2answers
1k 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: ...
0
votes
2answers
209 views

How can I optimize this query and support multiple SKUs?

My current query only can select one SKU at a time. I can leave salesite_id constant. If there is a way to also have varying salesite_ids that would be good too, but not necessary. Also any ...
4
votes
2answers
2k views

How do you set the pagesize, codeset and table space when creating a database in DB2?

I want to create a database in DB2. I found some information on this page I want to use only some options which are explained on the page: PAGESIZE CODESET TABLESPACE Then, I want to ...
0
votes
1answer
253 views

How can I use “select distinct” and have a range for my rows? [closed]

I wrote this code in PL/SQL developer and was wondering how I could have one row per range of t.ttt in the select distinct columns. Here's the SQL: select count (t.aaa), sum (t.bbb) from xxx t where ...
2
votes
2answers
4k views

How do I force a JOIN to use a specific index in MySQL?

I have a query that JOINs 2 tables; lineitem and part, select sum(l_extendedprice* (1 - l_discount)) as revenue from lineitem force index for join (l_pk), part where ( ...
2
votes
1answer
418 views

Help with SELECT queries

I need help with some queries. I struggled do find out how to do it, but I think I finally caught on or at least got the results I was looking for in the database. These are the tables (given by my ...
1
vote
3answers
698 views

Usefulness of a multi-attribute index

If an index has more than one attribute in it, is there any speed gained in a select statement whose where clause uses one of the attributes in the index? For example, take a table T with an index on ...
1
vote
1answer
265 views

SQL Server - Ignoring object dependencies to copy a DB (despite some column referenced in a sproc no longer existing)

First of all apologies for the novel but there's a lot to explain... We have over 100 databases for our product, 1 per server, each of which has variations on other ones (ideally they should all be ...
4
votes
0answers
135 views

How to Audit for Access with Cross Database Ownership Chaining

I've just joined the data team of a new company and we have a large SQL Server environment (100+ instances) and cross database ownership chaining is on by what I gather is a necessity. I'm looking for ...
13
votes
2answers
19k views

MySQL: Tree-Hierarchical query

SUB-TREE WITHIN A TREE in MySQL In my MYSQL Database COMPANY, I have a Table: Employee with recursive association, an employee can be boss of other employee. A self relationship of kind (SuperVisor ...
1
vote
2answers
880 views

list tables that are missing primary/foreign key in postgresql database

I've seen a ton of queries to list primary and foreign keys but how can I query for tables missing primary and foreign keys? PostgreSQL 8.4 and 9.x versions
2
votes
2answers
125 views

Joining 4 tables and 2 counts

I have four tables. UserMaster ---------- UserKey - PK UserName UserID - UNIQUE UserLogTransaction ------------------ UserID - FK:UserMaster.UserID LoginTime LogoutTime CallCenter ---------- ...
4
votes
1answer
3k views

query to identify all data types used in postgresql database tables

I don't want to know all data types, just all data types used in my database. Can this information be queried? PostgreSQL 8.4 and 9.x versions I currently need to know all data types for over 200 ...
3
votes
1answer
4k views

DB2 Defining remote database alias

I'm using DB2 9.7.0.3 for AIX. I want to select data from a remote database, also running DB2 9.7.0.3 for AIX, and insert it into the local database I'm connected to. I believe the query for this ...
2
votes
2answers
482 views

Execution plan flips Filter and Execute Scalar when using the PK, causes cast to fail

I have some data tables that where imported in from a flat file source so everything is varchar(max) except FileRecordID which is a int that hold the row number the data came from in the flat file ...
3
votes
1answer
5k views

Get week/month data

There is a table (MySQL). It's simplified structure: day DATE val INT UNSIGNED I need the average val for: every week containing a date from the table; every month containing a date from the ...
3
votes
2answers
691 views

How to concatenate a column after x rows?

I have a table with columns object varchar(255), frequency tinyint(3) unsigned, I want to concatenate the objects if the sum of frequencies reach a value. Currently I am doing this in PHP as .. ...