sql query profiler

In this article, the main description of the various connections in SQL and the scope of use, as well as the further interpretation of relational algebra and relational algorithms on the same query in different ways.Introduction to multi-table connectionsIn a relational database, a query tends to involve more than one table, because few have a single table, and i

the operation, all of which provide favorable evidence for optimizing the query. 1th, the 3 diagram IO overhead is relatively large, the 2nd graph estimates the number of rows is larger, and then according to other information, the first thought should be to build the index, not the words to change the query.Let's take a look at what optimization information the Database Engine Tuning Advisor can give us, and sometimes it can help us provide useful i

------------------------------------------------------------------------------------------------------------------------Displays the disk activity volume generated by the transact-SQL statement.Set statistics Io on-- Disable the disk activity volume generated by the transact-SQL statement.Set statistics Io off-- Display [return detailed information about statement execution and estimate the resource require

SQL query operation process and SQL operation processHere we can see the Query Processing of SQL in the book. In SQL, the query is achieved through the select statement and some auxilia

sqlpassion Performance Tuning Training Planindividual study translation, if there is falsehood, please do not hesitate to point out, thank you. Week 1:sql Server How to execute a query　　Before we go into the intricacies of SQL Server performance tuning, I'd like to start by enumerating how SQL Server executes a

+ @WHERE -- ----Execution statistics EXEC sp_executesql @COUNTSQL, N ' @RECORDCOUNT INT out ', @RECORDCOUNT out -- ----Count pages SET @PageCount = CEILING (@RecordCount * 1.0/@PageSize) -- ----Query statement DECLARE @SQL NVARCHAR (2000) DECLARE @ORDERBY VARCHAR (100) SELECT @ORDERBY = ' ORDER by Tbsdinfo. Iscommon desc,tbsdinfo.commontime Desc,tbsdinfo. Createtime DESC ' IF (@PAGEINDEX =1

1, first to understand what is called the implementation plan?An execution plan is a query scheme that the database makes based on the statistics of SQL statements and related tables, which are generated automatically by the query optimizer, such as an SQL statement that searches for 1 records from a 100,000-record tab

Date formatting statement and SQL Server statement during SQL Server Query The default datetime format of the Chinese version of SQL Server isyyyy-mm-dd Thh:mm:ss.mmm For example: select getdate() 2004-09-12 11:06:08.177 I sorted out the date format conversion methods that may be frequently used in

Article 1: how to optimize slow query SQL statements in MySQL56-Introduction to slow logs: in actual log analysis, there are usually a large number of slow logs, at the same time, there will be a large number of records for the same query. here we need to find the most problematic and optimized log in the actual log analysis, generally, the number of slow logs is

In programming languages with large numbers, the code is processed in the encoding order, but in SQL, the first clause to be processed is the FROM clause. Although the first SELECT statement appears, but it is almost always processed.Each step generates a virtual table, which is used as the input for the next step. These virtual tables are unavailable to callers (client applications or external queries. Only the table generated in the last step will b

Tags: databaseSQL databases T-SQL statement queryData files for attached databases650) this.width=650; "src=" https://s3.51cto.com/wyfs02/M01/96/06/wKiom1kcDfOB6lJHAAtJeP4PO9c190.jpg "style=" float : none; "title=" 1.jpg "alt=" Wkiom1kcdfob6ljhaatjep4po9c190.jpg "/>The category in the query table is the fruit of the factory date after 201-04-01650) this.width=650; "src=" Https://s3.51cto.com/wyfs02/M02/96/0

First of all, let's look at one of the steps here that translates into banner, which requires pivot, step-by-step Then look at the overall query results for the two query methods after the main table join So take a look at the latter query method is also through the industry after the conversion to do the join execution plan, you can see only the Word table

Recursive queries using CTE (common table expressions) ---- SQL Server 2005 and later versions A common table expression (CTE) has an important advantage: It can reference itself to create a recursive CTE. Recursive CTE is a public table expression that repeats the initial CTE to return a subset of data until the complete result set is obtained. When a query references recursive CTE, it is called recursive

Hibernate native SQL query Multiple table Association, SQL statement to pay attention to the problem@for ever 2009-9-4System environment:MySQL5.1Hibernate3.3The assumption is as follows:The entity classes Question and answer correspond to the data table Question and answer respectively.and the fields of table question and answer are mostly the same, and the numbe