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

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6
votes
1answer
1k views

How can a fill factor of 0 or 100 be the same?

As of my understanding, Fill factor of 80 implies that 20 percentage of each leaf-level page will be empty to enable future growth. I can't correlate how fill factor of 0 and 100 can be the same! Am I ...
25
votes
2answers
7k views

Check existence with EXISTS outperform COUNT! … Not?

I've often read when one had to check existence of a row should always be done with EXISTS instead of with a COUNT. Yet in several recent scenarios I've measured a performance improvement when using ...
2
votes
4answers
2k views

When do I use another type index than integer? (eg string) [integer vs string index]

I was reading about relational databases like sqlite and I always see the schema for user storage like: UserID (index) | Username | Password but wouldn't it be actually much faster to use Username ...
6
votes
1answer
246 views

Database restructure - beneficial?

I have a table for email messages. Then, I have a table that has the message parts. The Parts table contains a field_id, message_id, and data At the time I used Parts to name the table and ...
2
votes
2answers
14k views

Get username and/or IP address responsible for a query

I use the following query to find performance improvements in queries: SELECT TOP 20 SUBSTRING(qt.text, (qs.statement_start_offset/2)+1, ((CASE qs.statement_end_offset WHEN -1 THEN ...
8
votes
1answer
2k 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 ...
0
votes
1answer
386 views

RTF to Plain-Text? [closed]

Did you ever get the library from this post? We have a need to convert whole, large, whole tables worth of RTF information into something usable and would rather not reinvent if possible. Converting ...
3
votes
0answers
235 views

How can I search values, considering occurences, on more than one term in SQL Server CE?

I have a rather complex SQL query, that I actually received help from this SE site to come up with parts of. This query is designed to take a search term and search all relevant values in a database (...
3
votes
1answer
548 views

Cumulative Game Score SQL

I have developed a game recently and the database is running on MSSQL. Here is my database structure Table : Player PlayerID uniqueIdentifier (PK) PlayerName nvarchar Table : GameResult ID ...
5
votes
4answers
16k views

Difference between Full backup and Copy-only full backup

I saw in this link that full backup does not truncate the log. So what is the difference between full backup and copy-only full backup? For the log backup there is copy-only backup which prevent the ...
-6
votes
2answers
221 views

Inserting images in database [closed]

How can the images be inserted in a table? Var binary is not working in structured query language command prompt,what can be the syntax?
2
votes
2answers
193 views

MySQL #1064 error on line 2 [closed]

I'm quite new on learning SQL and I seem to be running into an issue with the following code: CREATE TABLE `read` (`order` NOT NULL UNIQUE AUTO_INCREMENT, `title` VARCHAR(50) NOT NULL, `url` ...
4
votes
1answer
328 views

What is the name of this type of query, and what is an efficient example?

The purpose is to find a parent, given it's children. For example, say you have a marketing package (aka a "combo"), and want to match it based on the products in it. Example table/data: create table ...
1
vote
1answer
978 views

Alter table move taking long time

I'm currently trying to compress a table in Oracle with the following statements: ALTER TABLE MYTABLE COMPRESS FOR OLTP; ALTER TABLE MOVE; My question is: the MOVE operation is taking forever and ...
1
vote
2answers
2k views

Obvious inefficiencies in this Netezza query?

Why might this query be taking nearly 2 hours to run when similar queries complete within a minute? CREATE TABLE T3 AS SELECT A.*, COALESCE(C.FIELD1,0) AS FIELD1A, COALESCE(...
1
vote
2answers
410 views

Most efficient way to perform table operations (spec. drop) on tables having table names that match a certain criteria

I am performing a schema dump of certain tables. This accompanied by dropping the tables that will be dumped. For example I need to drop all tables that start with, let's say, "SRC_". You guys think ...
1
vote
1answer
122 views

InnoDB query duration inconsistent

I am running a series of UPDATE commands on a nearly empty InnoDB table, and around 1 out of every 20-30 queries will inexplicably take 10 times as long as the others. For example, the first 20 ...
-8
votes
1answer
9k views

Using inner join to get data from multiple tables [closed]

I have 5 tables: A (a_id, a1, a2) B (b_id, b1, b2, a_id) C (c_id, c1, c2, b_id) D (d_id, d1, b_id) E (e_id, e1, e2, d_id) Here is some information table b have a_id match with table a (a_id). ...
4
votes
1answer
540 views

Splitting a table based on enum value

I am re-designing our company database, and am wondering whether or not to split this table up into two (or even three) different tables based on the type field. Prospects can become clients, and in ...
3
votes
3answers
14k views

Bulk update of all columns

I am wondering if PostgreSQL has an update query somewhat like their insert values syntax. I have an updated set of data in this form currently: INSERT INTO bought_in_control_panel(ID,PARENT_ID,...
-4
votes
0answers
120 views

Multi-row INSERT rejected? [closed]

What's wrong with my query? :( USE tempdb; IF OBJECT_ID('dbo.OrderTotals', 'V') IS NOT NULL DROP VIEW dbo.OrderTotals; IF OBJECT_ID('dbo.OrderDetails', 'U') IS NOT NULL DROP TABLE dbo.OrderDetails; ...
2
votes
1answer
1k views

Is it possible to reduce a group to a row based on some criteria?

I'd like to perform a select on a table involving a GROUP BY such that all rows that share the same set of identifiers are grouped together, but I want to reduce the group to one of the grouped rows ...
2
votes
1answer
122 views

Zero conversion in sql

Char convertion in Oracle have a pattern: to_char(number,'pattern') and provide option "s" to take sign to result, for ex: select to_char(10,'S999') from dual; will return +10, but when i check select ...
5
votes
2answers
372 views

One table used in two databases

I have a common product table in db1 and db2. I want to make it one table because it has one inventory (stock of products). What is the best solution to share product table among two different ...
0
votes
1answer
255 views

Update column value in entire database [closed]

In my database, I have around 30 tables, each with an emp_number (INT) column. How can I update the value of emp_number in all 30 tables?
-1
votes
1answer
102 views

How do I create a trigger that cascades new rows into another table?

I am having a table name link with two columns link1 and link2 and another table name hide with four columns hide1, link1,link2 and hide2. If i insert data into link table the data should insert into ...
2
votes
1answer
4k views

Extract MySQL information from a compressed tar.gz file

I have a back up-of a MySQL database which is contained in a .tar.gz file - I need to restore it. I've never had to do this before. The only way I can access the database is through phpmyadmin. There ...
1
vote
0answers
791 views

Creating view recursive query in Oracle DB results in ORA-00600 (ORA-600)

Hello Ladies and Gents, I've been trying to deploy a recursive query as a view in Oracle XE and Standard Edition, neither to much success. The query is located in this question here: http://...
2
votes
2answers
290 views

Changing ORDER BY direction causes performance issue

I use MySQL 5.6, and I have two tables each with 16M rows: CREATE TABLE IF NOT EXISTS `newsstudios` ( `id` int(11) NOT NULL AUTO_INCREMENT, `title` varchar(255) COLLATE utf8_unicode_ci NOT NULL, ...
0
votes
1answer
618 views

Does this error message indicate a SQL injection vulnerability?

I just took over management for a webservice and today I got a user report about this error. Now I'm no sql injection expert but does this error make this attack possible? Microsoft OLE DB Provider ...
1
vote
2answers
272 views

Is there any way to tell the number of matches found in a database value matched with LIKE?

Is there any way I can query a SQL-Server-CE database that will return the number of matches found in a cell value using LIKE (or MATCH AGAINST or any other method I'm not aware of, really)? EXAMPLE ...
4
votes
2answers
1k views

Multiple JOIN of 6 tables via 5 database instances

I'm currently reengineering my corporates user management and created a table which lists all users of all the 5 database instances. Next step is, that I need to write a query which shows me all the ...
7
votes
2answers
2k 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 ...
2
votes
1answer
14k views

MySQL Insert into table, where name = id, if not exist, then insert name and use that ID

I am producing a MySQL database that will store results for a particular sport. I have a table containing people, (PERSONID, FIRSTNAME, LASTNAME), another table containing animals names (ANIMALID, ...
8
votes
2answers
2k views

Convert units of measurement

Looking to calculate the most suitable unit of measurement for a list of substances where the substances are given in differing (but compatible) unit volumes. Unit Conversion Table The unit ...
0
votes
1answer
63 views

Wrong return results

I'm trying to grab all the rows that have a risk of critical or high, with the discription or synopsis or solution or cve like password. But it keeps showing all rows not just rows with a risk of ...
1
vote
2answers
766 views

Is it possible to build an UNDO framework for postgres?

I was thinking of a table which would automatically log all transactions made to other tables and the command to undo that modifications. So every time you issue an UNDO() command you would read the ...
-3
votes
1answer
174 views

What will the sql statement “DELETE FROM sales” do?

DELETE FROM sales; And if there are no other uncommitted transactions on the sales table. Which statement is true about the DELETE statement? It removes all the rows in the table and deleted rows ...
-1
votes
1answer
116 views

No predicate warning [closed]

I am getting a No predicate warning on this query. Can someone help? SELECT DISTINCT TOP 100 T0.nsid, T0.id, T0.version, ...
0
votes
1answer
480 views

How to profile a particularly slow or inefficient query

I'm currently writing queries for my database but this is the first time I've dealt with large data sets of any sort, and I'm now finding that I need to improve the performance of my queries. ...
0
votes
0answers
55 views

Any recommendation on tuning following query

My query has lot of select statements and unions. I think it is querying database multiple times and combining data. Is there a way we can eliminate multiple passes to the database? I would like to ...
0
votes
2answers
20k views

Query to search for a substring in xml

I use below query to search for a substring in whole xml(including node name and node value) SELECT * FROM tablename WHERE ( Charindex('abc',CAST([xmlcolumn] AS VARCHAR(MAX)))>0 ) I want an ...
1
vote
1answer
283 views

Relative cost of two similar queries involving XML columns

I have two queries as shown below which do the same thing. Here xmlcolumn is a column with datatype XML. I use these queries to search for a string anywhere in the XML column. I checked the execution ...
0
votes
1answer
570 views

xml queries with exist and contains giving unexpected results

I have a query as shown below. DECLARE @tbl TABLE ( id INT, col XML ) INSERT INTO @tbl VALUES (1,'<Root> <Row> <User>xyz</User> <Rowid&...
0
votes
1answer
217 views

Chaining System Query in MySQL

I have a table which maintains a user chain Here is the table structure +------+--------+ | id | user | +------+--------+ | 2 | 4 | | 10 | 4 | | 11 | 4 | | 1 | 2 | |...
2
votes
2answers
14k views

Dynamic Oracle Pivot_In_Clause

I'm kinda stuck. I want to do a user-role-relationship pivot table and my query so far looks like this: WITH PIVOT_DATA AS ( SELECT * FROM ( SELECT USERNAME, GRANTED_ROLE ...
2
votes
2answers
2k views

Query for master in Postgres replication

I'm trying to find out if there is a way to query for the master, from a slave PostgreSQL server that has been set up with server replication. From a slave, I can: SELECT pg_is_in_recovery() And ...
10
votes
6answers
41k views

Error 3154 while restoring a backup using WITH REPLACE

I have SQL 2012 with SP1 installed on my computer. I made a backup of a database test.bak. I have a database with the name test2 which is the same database, but the data changed. I want to restore ...
0
votes
3answers
2k views

Space used by databases file through linked server

I need to find out space used by database file for multiple databases through linked server(from one central server to multiple client SQL servers). I created view on client size, for all databases: ...
0
votes
2answers
1k views

SQL Server Maintenance Plan TSQL query to log the backup databases

Does anyone know how to use the TSQL task in SQL Server 2008 Maintenance Plan to log (insert) the databases that where backed-up? Imagine a Maintenance Plan that does the backup for DB1,DB2 and DB3. ...