how to tune sql query in oracle

In general, Oracle databases operate more efficiently than SQL Server databases in large data environments. From the query optimization alone, the two are quite different. Below, the author of the database query optimization of the difference to do a description, if there is not accurate place, but also please criticiz

WangWu 21 A1003 ZhouLiu 22 A1004 SunQi 22Note that after you set the number of query bars to 5 and the query succeeds, you must have a "SET ROWCOUNT 0" statement, or you can return up to 5 data at the next execution.For example, we first execute the following statement:set5selectfrom tb_employeeinfoThe result returned is

☆ Get all the table names of the database, all the column names of the tableSelect name from sysobjects where xtype= ' u ' Select name from syscolumns where id= (select Max (id) from sysobjects where xtype= ' u ' and name= ' table name ') ☆ Recursive query dataRecursive queries in SQL statements SqlServer2005 and Oracle two versions Using

Tags: PID pool table mina ext execution SID proc App--Query for the slowest SQL SELECT * FROM (Select Parsing_user_id,executions,sortsCommand_type,disk_reads,sql_text from V$sqlarea ORDER BY disk_reads Desc) Where rownum --Query corresponding session Select SE. Sid,se. Serial#,pr. SPID,TEI Username,se. Status,se. TERMINAL,TEI Program,se. MODULE,TEI Sql_address,st

Oracle/MySql/SQL Sqlserver paging query, oraclesqlserverBrief Introduction A brief summary of the paging query statements for Oracle, MySql, and SQL Server databases. Oracle paging

Steps for Oracle to execute SQL query statementsThe SQL query statement executed by Oracle is different from that of other statements. If the query statement is successfully executed, t

. First search in the shared pool for the same SQL statement, and if not, follow-up processing. 2. check that the syntax of the SQL statement is correct 3. Check the definition of tables and columns by looking at the data dictionary 4. Compile locks on the objects being manipulated so that the definitions of these objects cannot be changed during the compilation of the statements 5. Check

PL/SQL single-row functions and group functions A function is a program with zero or multiple parameters and a return value. Oracle has a series of built-in functions in SQL, which can be called SQL or PL/SQL statements. functions are mainly divided into two categories:Singl

Many of my friends use mysqllimit for paging to oracle and do not know how to write paging. In fact, oracle paging is similar to mssql paging. Next I will introduce oracle paging statements. Many of my friends who use mysql limit for paging to oracle do not know how to write paging. In fact,

:A. Needs to be queried from the database: Totalrecords. "SELECT COUNT (*) from TableName"B. The most basic needs of user-provided: PageSize and Pagenow. (Personally think this is the premise of pagination algorithm)C. Derived from other variables: TotalPages, Beginrow and Endrow. (it needs to be calculated that Beginrow and endrow are required for paging queries, TotalPages is the information that the page needs to provide). Specific formula for calculation: Totalpages:if ((totalrecord

SQL connection query for Oracle databasesPrefaceIn reality, there is such a requirement that sometimes the data we need to query is in multiple tables, so how to query data from multiple tablesWhat about it? In this case, you need to use table connections to perform queries.

Oracle processes query statements in three major stages: parse, execute, and fetch ). Oracle processes query statements in three major stages: parse, execute, and fetch ). Steps for Oracle to execute SQL

☆Retrieve all table names and column names of the databaseSelect name from sysobjects where xtype = 'U'Select name from syscolumns where id = (select max (id) from sysobjects where xtype = 'U' and name = 'table name ')☆Recursive Data QueryRecursive query of SqlServer2005 and Oracle in SQL statementsI used Oracle before

Different databases: oracle mysql SQL Server DB2 infomix sybase paging query statement, infomixsybase Paging query statements used in different databases: Current page: currentpagePage size: pagesize 1. Oracle Database Select * from (select A. *, rownum rn from (QUERY_

The paging query method of DB2 is not the same as that of paging query statements in Oracle and SQL. The following describes the differences between paging query in DB2 and paging query in other databases.

BackgroundWhen using Oracle or other databases, using the LIKE keyword for fuzzy query is commonly used by people, in the use of pure Chinese environment is very easy to use, there are some wildcards can be used, but in a pure English environment, the size of the need to accurately match the problem, the main reason is the problem of string FL like '%{0}% ' and Here like after is a string, so

This article summarizes the Oracle implementation of page query SQL syntax, collation for everyone for your reference, details are as follows: 1. No order by sort of the wording. (Highest efficiency) After testing, this method costs the lowest, only nested one layer, the fastest! Even if the amount of data query is l

Use this SQL statement Select*FromTree View the raw data as follows: The following figure shows the result of a tree query (including the fields ROOT, LEVEL, IS_LEAF, and PATH ): Execute the following SQL statement: SelectConnect_by_root (child_col) root,Level, Decode (connect_by_isleaf, 0,'No', 1,'Yes') Is_leaf, sys_connect_by_path (child_col,'/') Path F