how to tune sql query in oracle

Oracle experience 5 -- add, delete, modify, query, and @ oracle transaction processing @ Case Analysis1. add, delete, modify, and query DML (Data Manipulation Language-Data operation Language) in Oracle can be executed under the following conditions: insert Data into the tab

session is completed by alter session. If the session has no special settings, it will be consistent with nls_instance_parameters.The character set of the client must be the same as that of the server to correctly display non-ASCII characters of the database. If multiple settings exist, alter session> environment variable> registry> parameter fileThe character set must be consistent, but the language settings can be different. We recommend that you use English for language settings. If the char

also to reduce the duplication of shared memory information, Oracle can accurately count the frequency of SQL execution.2, where the condition order after the influenceThe condition order after the WHERE clause has a direct effect on the query of the large data scale. Such as:Select * from zl_yhjbqk where dy_dj = ' 1KV or less ' and xh_bz=1Select * from Zl_yhjbq

impact.Because it wants to globally coordinate the data cache and ensure that the cached data that is connected to each instance is consistent, the following three contradictions are magnified:1. Cache contention2. Excessive I/O3. LockThat is, if there is a problem with the RAC, the problem will be much greater, for example, if the SQL does not use binding variables to cause cache contention, it is more serious to use RAC.All in all, if your server's

Oracle archive data query (partition query) the SQL statement used to query 201212 month data records is as follows: SQL code www.2cto.com SELECT COUNT (DISTINCT (c. caller_nbr) AS emp_use_count FROM tab_pub_calllog c WHERE TO_CHA

Label:Pivot and Unpivot can be used in Ms-sqlserver 2005 and Oracle for Row and column conversions, but dynamic columns are not supported. Here, the case and then else end statements are used to implement the row and column conversions. How to implement dynamic columns at the bottom. Below is an example of a Student score table: ID Name Account Score 1 in three languages 602 Zhang Three Mathematics 653 Three foreign Languages 704 John Doe Language 805

; OWNER Directory_name Directory_path ---------- ------------------------------ ------------------------------ SYS Bdump/opt/oracle/admin/eygle/bdump Then create an external table: Sql> CREATE table Alert_log (text VARCHAR2 (400)) 2 Organization External ( 3 Type Oracle_loader 4 default directory Bdump 5 Access Parameters ( 6 Records delimited by newline 7 Nobadfile 8 Nodiscardfile 9 Nologfile

This article describes how to query and operate Oracle tablespaces. For more information, see This article describes how to query and operate Oracle tablespaces. For more information, see I. Query 1. query the usage of

the data is consistent, but nothing is perfect. The cost of the Begin Tran is that all the resources locked by the SQL statements cannot be released until the commit is committed before committing.It can be seen that if the BEGIN TRAN too many SQL statements, the performance of the database is poor. Before this large transaction commits, it is bound to block other statements, resulting in many blocks.The p

Alibaba Cloud SQL Intelligent Query analyzer, a database query and analysis management tool developed by delphi. To facilitate your work, you can use a database query and analysis management tool developed by delphi to share with you the following features: 1. Due to the use of ADO connections, it theoretically sup

. Move the table space data file #先确定数据文件据在表空间 Sql>select tablespace_name,file_name from Dba_data_files where file_name= '/u01/test.dbf '; #open状态 Sql>alter tablespace test offline; Sql>host move/u01/test.dbf/u01/oracle/test.dbf; Sql>alter tablespace Test rename datafile '/u

Background: Oracle queries the current asset status, including asset information (table 1), Asset maintenance status (table 2), Asset retirement status (table 3)As follows:Asset Information:Asset Repair:Asset retirement:After the asset application is finished, you can apply for maintenance and scrap of the current asset, with two processes in service, one for maintenance and then maintenance. The corresponding need to start the corresponding process t

continue to process the next suspended task.SQL language and TSQL (called tsql,oracle plsql in SQL Server) language is an advanced descriptive languageWhen a SQL statement is complicated, imagine that a SELECT statement is accompanied by multiple join1 use [Gposdb] 2 GO 3 SELECT * FROM [dbo]. [Ct_append] As a 4 INNER JOIN 5 [dbo].[ Ct_fuelingdata] as B 6 on A.

done by querying the data dictionary, which means more time is spent(4) Reduce access to the database: Oracle has done a lot of work internally: Parsing SQL statements, estimating index utilization, binding variables, reading data blocks, etc.;(5) Reset the ArraySize parameter in Sql*plus, sql*forms and pro*c to incre

Briefly describe the query and Solution to deadlocks in Oracle databases, and briefly describe oracle Deadlock PrincipleIf you update or delete a column in a table in the database, this statement is not mentioned after the execution.The statement that updates this column of data is in the waiting state during execution,In this case, this statement has been execut

Group By Type field, sort by code, and remove the first record from each group Method One: Select Type,min (code) from Group_infoGroup By type; Note: The columns following the select are included in the GROUP BY clause, or with aggregate functions, otherwise there will be a syntax error. Method Two: SELECT * FROM (SELECT Z.type, Z.code, Row_number ()Over (PARTITION by Z.type Order by Z.code) as code_idFrom Group_info Z)WHERE code_id = 1; Here the Over () is the

Oracle query optimization and oracle Optimization 1. Reasonably sort query Conditions Oracle uses the bottom-up sequence to parse WHERE data. From the perspective of performance optimization, we recommend that you write the conditions that can filter out a large number of re

Explain the oracle table complex query instances and explain the oracle instances Group by and having clauses Group by is used to group statistics on query results, The having clause is used to restrict group display results. Summary of data groups 1 grouping functions can only appear in the selection list, having, or

Oracle Database Connection + addition, deletion, modification, and query operations tutorial, oracle addition and Deletion Connect to the oracle database and use $ Conn = oci_connect ('account', 'Password', "(DEscriptION = (ADDRESS = (PROTOCOL = TCP) (HOST = ip address connecting to

integrality control, support distributed database benefit distributed processing has portability, The advantages of compatibility and connectivity are much favored by users, widely used in Internet database platform, its spatial technology can manage geographical information more effectively and realize the storage and management of massive spatial information. Based on the experience of Oracle database application, this paper expounds the experience