query tuning in sql server

Process of each stage of SQL Server Query Processing Unlike other programming languages, SQL is most characteristic of code processing. In programming languages with large numbers, the code is processed in the encoding order, but in SQL, the first clause to be processed is t

data: Select [All | distinct] column1, column2, column3 ..... From tablename1 [, Table2, table3. ..] [Where…] [Group by column_name] [Having...] [Order by column_name [DESC | ASC] Common set functions: Sum (); AVG (); min (); max (); count (); SQL Server supports five constraints: Default constraint (default constraint), primary key constraint (primary key constraint), check constraint

Due to the diversity of business logic, it is often required to query data in different databases in SQL Server, which results in the requirement of distributed query.Now I will be in the development of several types of queries summarized as follows:Version 1.access--Establish a connection serverEXEC sp_addlinkedserver--The name of the linked

where UserName like ' Zhang [0-9] sister '/' Zhang [A-z] sister '/' Zhang [0-9a-z] sister '; [A-z] The default collation is case-insensitive, so the case can be written out ^ (non): select * from Users where UserName like ' Zhang [^0-9] sister ' (middle not number)/not like ' Zhang [0-9] sister ' (do not take ' Zhang [0-9] sister ' data); Note: 14.null Value Processing ①sql null cannot be calculated with =/!=; ②is null/is NOT NULL; ③ any value with

keysRow: sqlserver2000 not supported Test data:A total of 3.2 million data, each page shows 10 data, respectively, 20,000 pages, 150,000 pages and 320,000 pages were tested. Page number, top scheme, max scheme, row scheme20,000, 60MS,46MS,33MS150,000, 453ms,343ms,310ms320,000, 953ms,720ms,686ms is a paging scheme that uses a program to stitch SQL statements.User-mentioned SQL statements do not need to writ

SQL Server query performance optimization analysis transactions and locks (2 ). Step 1: Execute Example 2 and Example 3 code in the query analyzer. (This is the example in the previous article SQLSERVER query performance optimization analysis transactions and locks (2) -- Ex

maintain consistent performance. The syntax change tells the optimizer to ignore all parameter values, just determine optimize for unknown and omit the parentheses and variable names. Determining optimize for will cause Parametercompiledvalue to disappear from the Showplan XML output, just as parameter sniffing (sniffing) did not occur. Regardless of the parameters passed, the final plan will be the same, and may give more predictable query performan

SQL server implements recursive query. This example describes how SQL server implements recursive queries. We will share this with you for your reference. The details are as follows: Sometimes recursive queries are required for tree-structured data. After searching for the d

Copy Code code as follows: /*01. Introduction to 02.sql XML: --by Jinjazz --http://blog.csdn.net/jinjazz 05. 06.1, XML: Ability to recognize elements, attributes, and values 07. 08.2, XPath: Addressing language, lookup similar to Windows directory (go to the wall if you don't use the dir command) 09. 10. Syntax format, which can be combined as a condition: 11. "." Express oneself, "..." Said the father, "/" said the Son, "

I believe that you will often encounter the problem of exporting SQL Server query results to Excel. If the number of export times is small, simply "Save Results; 1.1 prepare the query statement 1.2 select a database and start the Import and Export wizard 1.3 select a data source 1.4 select a target 1.5 1.6 1.7 1.

value is 0, which means that the maximum number of connections for SQL Server is 32767 by default.Get the maximum number of connections currently set:Select value from Master.dbo.sysconfigures where [config]=103How to monitor the number of SQL Server connections/* Query the

SQL Server database paging query has been a short board of SQL Server, idle, come up with several methods, assuming that there are table article, Field ID, year ... (other omitted), Data 53,210 (customer real data, quantity is not large), paging

(*'freetext_string' [] []) Example:　　　　Search Image FieldIn the field of the image type of SQL Server 2005, not only can you store graphics files, but you can also store many file types such as executables, music files, text files, and so on. SQL Server 2005 supports full-text search for the contents of some files

@num intSet @num = 1;WhileBeginIf @num%2=0BeginPrint @numEndSet @num [Email protected]+1EndThings: The ability to guarantee a large number of operations in a batch, if there is a failure, you can return to the original state. Ensure that the operation is correct.Only if the data changes, it will trigger things, that is, to increase the deletion.Classification:Explicit transactions (manual write required)Implicit transaction (MSSQL Default, no manual required)Begin tryBEGIN Tran-Set the point of

On an old Web server, the website ASP + SQLServer2000 was used. Since year 56, it has been used smoothly, so it has not been handled properly. On an old Web Server, the website ASP + SQL Server 2000 was used. Since year 56, it has been used smoothly, so it has not been handled properly. A few days ago, I found that t

In SQL Server, the optimizer dynamically determines a low-cost connection policy between two tables based on the table or index structure and table data. SQL Server has three connection policies: Nested Loop Join, Merge Join, and Hash Join. Nested Loop Join: The optimizer selects a table with a small amount of data as

Tags: SQL Server database queriesRecently has been studying the blog, in fact, is now a popular self-media, it is interesting that the netizens have written their own blog, the establishment of a small station, and now went to the platform for others to work free, but also enjoy themselves, do not know what the situation.Blog information:Topics: Learning topics related to reading notes.Web site: Use a. NET

The following table lists all keyboard shortcuts provided by the SQL Server Query analyzer. Activity shortcuts Bookmarks: Clear all bookmarks. CTRL-SHIFT-F2 Bookmarks: insert or delete bookmarks (switch ). CTRL + F2 Bookmarks: Move to the next bookmarks. F2 function key Bookmarks: Move to the previous bookmarks. SHIFT + F2 Cancel

Recently, I have just received a copy of Microsoft SQL Server 2008 English version of the book from the most valuable expert project group-"Inside Microsoft 2008:t-sql Querying" (http:// www.microsoft.com/learning/en/us/book.aspx?ID=12804locale=en-us), roughly turned over and found a lot of changes in content, both new chapters, but also based on

server through sp_addlinkedserver Use steps Creating a linked server from sp_addlinkedserver Example: Exec sp_addlinkedserver ' Remotelinkmasterdb ', ', ' SqlOleDB ', ' 172.21.1.1\mydbinstace ' Create a linked server with sp_addlinkedsrvlogin using an account, password Example: Exec sp_add