Oracle

When analyzing SQL performance, it is often necessary to determine how much SQL is consumed by resources, as summarized below:1 View questionable SQLSelect substr (To_char (s.pct, ' 99.00 '),2) || '% ' load,S.executions executes,P.sql_textFrom

For exampleFirst, create a, b two tables, in order to facilitate understanding, both tables create only one field column, respectively, A_col and B_col, add a tableData 1, 4, 5, 9, add B table Data 2, 3, 4, 5.Second, enter the following statement:

Previous time to do questionnaires, customers create custom questionnaire content, including topics and options content;Then you need to go around the questionnaire,,,, trouble.So to search the internet everywhere, there is no direct result, and

MISSES in library cache during parse:1Translation: The number of hard parse occurrences in the resolution is 1, which means hard parsingMISSES in library cache during parse:0Translation: The number of hard resolutions that occur in the resolution is

Partitioned tables in Oracle are frequently used in systems that are more frequent in systems with large amounts of data.When you refer to a partitioned table, you must first understand what a partition is. In fact, the so-called partition is simply

Oracle DB allows external tables to be queried in read-only form. The external table can be stored in any storage device that can be read by Oracle DB, its contents are not saved in db, the DB only saves external table metadata,db can query (join,

Oracle installation: Merging two files Global Users: AchievecPassword: Admin123456Users: ScottPassword: TigerOracle Development tools: SQLPLUSW and sqlplus and PL/SQL developer Oracle directives: Conn[ect]

1. Oracle Row-to-column and column-changing careerThe most common row-to-column, the main principle is the use of the DECODE function, aggregate function (SUM () Max ()), combined with the group by group implementationMAX (DECODE (SW. SBBL, ' 1 ',

Oracle uses JDBC for additional pruning checksDatabases and tablesTableUSERS(USERNAMEVARCHAR2(20)  not null,   PASSWORD  varchar2 20) ) altertable users   add constraint  u_pk primary  key  (USERNAME) /*** Jdbcexample.java**

1. What is a view?A view is also known as a virtual table, which is a logical representation of a set of data.The view corresponds to a SELECT statement, and the result set is given a name, which is the view nameThe view itself does not contain any

1.Redo Log Features Redo logs are primarily disk I/O, logging database operations to log files. (Disk i\o performance can be a bottleneck) There is only one active LGWR (log writer) process per instance, at least two log groups (logfile

Oracle learning-dmp file (table) Import and Export, oracledmp Oracle learning-dmp file (table) Import and Export 0 Source: Ninth Information Technology Improvement Course of Langfang Normal University, Zhang Wenkang Add to

Oracle (4) --) Advanced subquery ~) This section will discuss the more complex application of instant queries, mainly to simplify SQL and improve performance from the aspect, of course .. There are many ways to improve performance .. Today I

Oracle (iii) -- other database objects (Summary Series)Opening section ·_·In addition to views, other database objects include sequences, synonyms, and indexes. The most important part is the sequence (associated with the trigger). synonyms and

How to grant users the permission to view Stored Procedure definitions and stored procedure Permissions A user asked me how to grant a user the permission to view the definition of certain stored procedures, rather than letting the user modify or

Oracle recursive query and Oracle recursive query 1 select. accountcodeid,. accountcode,. accountcodename, 2 SYS_CONNECT_BY_PATH (. accountcodename, '\') as fullname,. parentcodeid, level 3 from fm_accountcode a 4 where. accountcodeid> = 10000 5

The instance explains how to handle 80 million data records temporarily and how to handle 80 million data records. Recently, When I deduplicate a million data business table, the de-duplication operation was stuck. The following is a simple review. 1

The efficiency of exists and not exists usage in and exists statements in oracle. oracleexists Blog source (exists and not exists usage in oracle): http://chenshuai365-163-com.iteye.com/blog/1003247 Blog source (the efficiency of in and exists

Database selection of different service logic Constraints I think the constraints on data tables are still very useful. At least there are many database optimizations, which can greatly improve the retrieval efficiency and play a significant role,

Why can oracle users who do not have permission to log on with sysdba? oraclesysdba I created a user, create user lisi identified by lisi. When I log on with sqlplus: Cmd-> sqlplus lisi/lisi cannot go in-> then lisi as sysdba will go in, so I have