Oracle

Oracle like '%... %' optimized 1. Try not to use like '%' 2. For like '%' (not starting with %), Oracle can apply index3 on colunm. For like '%... '(Not ending with %), you can change it to like' % '4 in the form of reverse + function index. if you

Delete redo log group or member 1. before deleting log groups, determine 3 points: 1. the instance must have at least two groups instances, regardless of the number of member for each groups; 2. you can delete a group only when its status is

Oracle index details-2 oracle index details-1 http://www.bkjia.com/database/201304/205591.html I. Index restriction: Index restriction is one of the common mistakes that some inexperienced developers often make. Many traps in SQL statements will

Oracle job failure solves a problem where the JOB in the latest business database is always unable to be executed at regular intervals without any errors. Today I took the time to read it. It should be that the JOB can be executed manually if it

This section describes how to extract data from the data warehouse to a flat file. The data warehouse table is EMP and the destination file is emp.txt. Gtlions = # select * from emp; empno | ename | job | mgr | hiredate | sal | comm | deptno -------

Some scattered notes in Oracle prevent repeated insertion of an SQL insert record. However, in some special applications, before inserting a record, you must check whether the record already exists, the insert operation is performed only when the

By using bat batch processing, visual operations on oracle backup files in dmp format of oracle are generally borrowed from PL/SQL. Now we need to export the oracle dmp backup file at the same time, and just use his command to create a bat batch

Recently, I tried to write a project on the oracle11g database creation method, but I couldn't help it. Because I have never used Oracle data development before, And I used everything in the cloud, seeing that the theoretical knowledge is useless,

Oracle System Administrator basics: Oracle Data Dictionary for Oracle system administrators, Oracle Data Dictionary is like a treasure house: it is an important part of ORACLE Database, provides information about databases, such as database

Oracle 10g rac deployment documentation host network configuration considerations: static IP Address Configuration: static gateway should specify hostname not to appear in the loopback address! If you have started the single-host asm service, stop --

Ignore the record environment 11gR2 In the alter file. centOS64bit Problem description: [SQL] Tue May 07 18:40:01 2013 Thread 1 cannot allocate new log, sequence 78 Private strand flush not complete Current log #4 seq #77 mem #0:

Summary of Oracle Client tool connection to database server problems often encounter problems that PL/SQL Developer and other Client-dependent tools cannot connect to the Oracle Database Server. So far, it has not been fully clarified. I will first

The Oracle subquery statement sets another subquery statement in one select statement: the name of the person with the highest salary in emp: SQL> select ename, sal from emp where sal = (select max (sal) from emp); persons with higher salaries than

Connect by prior recursive algorithm in oracle start... connect by prior clause usage connect by is used in structured queries. Its basic syntax is: select... from tablename start with condition 1 connect by condition 2 where Condition 3; example:

[Oracle] the Flashback flash back mechanism Flashback is intended to be difficult if you have misperformed data and submitted the data before it has been Flashback. Some people may say that the backup can be used to restore the system to a previous

[Oracle] statistical information and dbms_stats Package 1. Roles of Statistical Information Oracle CBO-based optimizer relies heavily on statistical information when generating execution plans, you can think of CBO as a complex mathematical model,

The use of dbms_job (scheduled task) in oracle can be considered as a scheduled task. 1. CREATE test TABLE SQL code CREATE TABLE TEST_DATE (A DATE); 2. CREATE a custom process SQL code CREATE OR REPLACE PROCEDURE TEST_MYPROC AS BEGIN INSERT INTO

Oracle analysis functions 1. automatic summary functions rollup, cube, 2. rank function, rank, dense_rank, row_number 3. lag, lead function 4. increase the moving of sum, avg, and 5. ratio_to_report processing function 6. first, last base-based

[Oracle] Local VS Global partition index in Oracle, the index and table can also be partitioned. There are two types of partition indexes: Local and Global ). 1. The Local index is created using the LOCAL keyword. The partition boundary is the same

Comparison and analysis of historical SQL statement execution plans in Oracle Based on the CBO optimizer environment, the generation of SQL Execution plans relies on the authenticity and integrity of statistical information. Such as column