sql query analyzer 2017

It is understood that the vast majority of developers have a thorough understanding of indexing, limited to the fact that most daily work has no chance, and there is no need to care about or understand indexing, when a query is too slow, you can create an index based on the query conditions. When another query is slow, you can create an index, or directly send th

. 21. Use select top 100/10 Percent to limit the number of rows returned by the user or set rowcount to limit the rows to be operated. 22. Before SQL2000, do not use the following words: "is null", "23. Use Query Analyzer to check the SQL statement Query plan and evaluate and analyze whether the

the lock time. 21. Use select Top 100/10 percent to limit the number of rows returned by the user or set rowcount to limit the rows to be operated. 22. Before SQL2000, do not use the following words: "Is null", " 23. Use query analyzer to check the SQL statement query plan and evaluate and analyze whether the

It is understood that most developers have a smattering of understanding of the index, limited to most of the daily work no opportunity, what is not necessary to care about, understand the index, it is really a query too slow to find the query conditions to build an index on OK, which day again a query slow, and then establish an index is, Or simply send the enti

rows returned by the user or set rowcount to limit the rows of the operation.22, before the SQL2000, generally do not use the following words: "Is NULL", "23. Use Query Analyzer to view the SQL statement's query plan and evaluate whether the analysis is an optimized SQL. Th

be operated.22. Before SQL2000, do not use the following words: "is null", "23. Use Query Analyzer to check the SQL statement Query plan and evaluate and analyze whether the SQL statement is optimized. Generally, 20% of the Code occupies 80% of the resources, and our optimi

because a small data type is more efficient.When data type conversion is required in the query, the execution time is increased, so the conversion of data type is avoided as much as possible.If you cannot avoid it, you need to carefully define the conversion of the data type.This article is the first of this series of tutorials, followed by more "How to write Better SQL

/* Use ms SQL to implement the T-SQL code for Distributed Query of heterogeneous databases */ Exec sp_addrole server 'Ms _ SQL ', '', 'sqloledb', '2017. 18.9.20'Exec sp_add1_srvlogin 'Ms _ SQL ', 'false', null, 'sa', 'capec '/* C

Myth 1. An index is established on a table and an indexed column is used at query time, and the index is bound to take effectFirst of all, it is wrong to make it clear that the SQL Server query optimizer is a cost-based optimizer that determines whether to use an index, what type of index to use, and which index to use, through a series of complex judgments.

rows to be operated.22. Before SQL2000, do not use the following words: "is null", "23. Use Query Analyzer to check the SQL statement Query plan and evaluate and analyze whether the SQL statement is optimized. Generally, 20% of the Code occupies 80% of the resources, and ou

set rowcount to limit the rows to be operated. 22. Before SQL2000, do not use the following words: "Is null", " 23. Use query analyzer to check the SQL statement query plan and evaluate and analyze whether the SQL statement is optimized. Generally, 20% of the Code occupies

the cursor. Optimistic read-only value When nolock is specified, the table with the specified prompt is read-only in the cursor. 16. Use profiler to track the query, obtain the time required for the query, and locate the SQL problem. Use the index optimizer to optimize the index. 17. Pay attention to the difference between Union and Union all. Good union all 18.

] ( [ID] [int] IDENTITY (1, 1) not null, [UnqValue] [uniqueidentifier] not null, [IntValue] [int] NOT NULL ) ON [PRIMARY] GO Alter table [dbo]. [tabTest] WITH NOCHECK ADD CONSTRAINT [PK_tabTest] PRIMARY KEY CLUSTERED ( [ID] ) ON [PRIMARY] GO Alter table [dbo]. [tabTest] ADD CONSTRAINT [DF_tabTest_unqValue] DEFAULT (newid () FOR [unqValue] GO Create index [IX_tabTest_unqValue] ON [dbo]. [tabTest] ([unqValue]) ON [PRIMARY] GO Declare @ I int Declare @ v int Set @ I = 0 While @ I Begin Set @ v

= @ I + 1 End Then we execute two queries and view the execution plan. (The query plan can be opened in the query menu of the query analyzer. At the same time, The GUID of the first query on the graph is obtained from the database, you can set this paramet

submitted to the storage engine for execution and caching. The approximate process is as follows: execution plans are at the heart of performance, and the storage engine accesses and returns data to the client based on the execution plan, and a good execution plan can efficiently and quickly complete the data request, while an unreasonable execution plan can increase the run time of a simple request from a few seconds to a few hours. and execution planning is also a core tool for analyzing perf

or set rowcount to limit the rows to be operated. 22. Before SQL2000, do not use the following words: "is null", "23. Use Query Analyzer to check the SQL statement Query plan and evaluate and analyze whether the SQL statement is optimized. Generally, 20% of the Code occupie