Oracle

Copy Code code as follows: If you have multiple tables in the-->FROM clause, select the table with the least number of record bars as the underlying table --> parsing WHERE clause is a bottom-up filter condition must be in order

Copy Code code as follows: SELECT Height,/*height of the b-tree*/ blocks,/* blocks in the index segment * * Name,/*index name */ Lf_rows,/* Number of leaf rows in the index * * Lf_blks,/* Number of the leaf blocks in the index * *

1. Nested loop joins (NESTED Loop join)A nested connection divides the data set to be processed into an outer loop (a driving data source) and an inner loop (driven data source), which executes only once (executes first), and the number of times the

Oracle RAC provides two ways to achieve load balancing, the first is pure technology, that is, when users connect, depending on the current load of the system to decide which node to handle the user request; the second is business-oriented, and the

If Oracle unfortunately encounters undo corruption in operation, the best approach is full recovery, but if there is no backup, you can take an unconventional approach (taking advantage of the hidden parameters of Oracle) and If Undo contains

In the development of what you should have done similar department management such functions, in general, a department below there is the next level (sub departments), this level is similar to a tree. In this case, the parent department and the

In the development process may be declared that contains a table does not have a field cursor, to solve special problems, this article will detail this type of problem, need to know more friends can refer to the Where data.* is a table and then

In the development process may use the Oracle Table demo Operation statement, this article will introduce this, needs the friend may refer to under SQL code Copy Code code as follows: --Created on 2010/07/29 by Wangnan Declare --Local

How do you get the maximum date for Oracle in your development application? This article will provide such a method of obtaining a friend that needs to be referenced under SQL code Copy Code code as follows: --Created on 2010/06/08 by NAN

SQL code Copy Code code as follows: CREATE TABLE Test (a VARCHAR2 (a), B VARCHAR2 (), C number,d VARCHAR2 (20)) INSERT into Test VALUES (' A1 ', ' B1 ', 1, ' t '); INSERT into Test VALUES (' A3 ', ' B3 ', 3, ' t '); INSERT into Test

If there are two users in Oracle, A and B, then if a is to access a table owned by B, the statement should be: Copy Code code as follows: SELECT * from B.tablename. My question is, can you change the Oracle's settings by changing the

As a DBA, one of the most common scenarios:To create a table space: Copy Code code as follows: Createtablespacethink DataFile '/u01/app/oracle/oradata/orcl/think.dbf ' size100m autoextendonnext10mmaxsize4096m

1. Basic Concepts Two functions: To complete the constraints of complex business rules that are difficult to complete by database integrity constraints, to monitor various operations of the database, and to implement audit functions. Triggers are

Sometimes it is not clear that all allowable values for some parameters can be obtained from the following two methods 1. Directly input the wrong value, let the error to hint Copy Code code as follows: Sql> alter system set

Oracle's Listener service is registered in two different ways, dynamic and static, respectively. Dynamically registered services are displayed at LSNRCTL status as ready, while static services are unknown. 11g2 the previous version, the listener is

Solve connect to Idle instance problem First step View Oracle_sid. [Oracle@linuxserver ~]$ Echo $ORACLE _sid Cjdl The SID here is the same as initializing the file Spfilecjdl.ora. [Oracle@linuxserver ~]$ CD $ORACLE _home [Oracle@linuxserver 11.2.0

Deleting a nonexistent table in Oracle, such as drop table notexisttable, prompts: ORA-00942: Table or view does not exist, If you use a program to execute the statement, you will report an exception, which requires us to determine whether the

1.1 Database Data full-Library backupNote: This operation requires the database to be started. Switch to an Oracle user and create a backup usage directory on the OS side: Mkdir/oracle/backup Log in to the Oracle database and create a backup

1. Log on to the server create Rman automatically delete archive log scripts two days ago [oracle@108 ~]$ cat >>del_ora_log.rman Crosscheck Archivelog All; Delete noprompt expired archivelog all; Delete noprompt force archivelog until time ' sysdate-

Oracle offers a number of ways to reduce the time spent parsing Oracle SQL expressions, which can drag down the system's performance when performing complex queries with a large number of execution plans. Now let's take a brief look at several of