Oracle

Dual is a virtual table used to form the select syntax rule. oracle ensures that there will always be only one record in dual. We can use it to do a lot of things, as shown below: 1. To view the current user, you can execute the following statement

Before installing the oracle database, remember that the Instance name is generally orcl by default. Remember that the user name and password are not difficult to uninstall the database ------- first, stop all oracle-related services, check whether

Suppose there is a table TEMPSQL> SELECT * from temp; id info ---------- limit 1 aaa 2 bbb 3 ccc SQL> delete from temp id = 1; 1 row deleted SQL> COMMIT; commit complete SQL> SELECT * from temp; id info ---------- restore 2 bbb 3 ccc restore Data

Today, I encountered an Oracle varchar2 Sorting Problem: my current project is an integrated customer service system that needs to interact with multiple external systems. An external system provides us with a sorting field of the varchar2 type.

SAP programs (such as R3trans, tp, wp, etc.) connect to the Oracle database in three steps: 1. use OPS $ to log on to the Oracle database. Use OPS $ to verify the operating system. Set the OS _authent_prefix and remote_ OS _authent parameters on

1. LOOP is the simplest and infinite LOOP, and can only be terminated by EXIT. SQL code declare starts number: = 1; counts number: = 20; begin loop dbms_output.put_line (starts); starts: = starts + 1; www.2cto.com exit when starts> = counts; end

The database user account includes the following content: Unique User Name, verification method, default table blank, temporary tablespace, user profile, user group, and lock status. Pre-defined accounts: SYS and SYSTEM view the current user SQL>

1. ORACLE optimizer has three types of A, RULE (RULE-based) B, COST (COST-based) c, and CHOOSE (selectivity) to set the default optimizer. various declarations of the OPTIMIZER_MODE parameter in the ora file, such as RULE, COST, CHOOSE, ALL_ROWS,

1. Actual requirements: Description: in the preceding table, a student has multiple courses and scores, and now wants to have an SQL statement that combines the course name and score for display, www.2cto.com: all the courses and scores of this

The oracle Database allocates table space, creates users, and assigns user permissions. Operation 1. creates a temporary tablespace./* Create temporary tablespace */create temporary tablespace student_temp tempfile 'd: \ oracle \ product \ 10.2.0 \

When do you need to use these two time periods? To put it simply, if you pay off the monthly subscription product you purchased on April 9, March 15 at the end of the month, you will be charged for 17 days, at this time, you should determine whether

Oracle Database Performance Optimization-factors that affect oracle performance can be divided into hardware and software. This article analyzes the oracle database architecture, in terms of hardware, An OLTP system is proposed to optimize the

Create or replace procedure pro_cursor_type_Vast_tmp table3 % rowtype; type c_type is ref cursor; cur c_type; v_taname varchar2 (100); begin www.2cto.com v_taname: = 'a '; open cur for 'select * from table3 where taname =: a order by taid desc '-- a

Processing Process 1 when a service cannot be started normally. The service cannot be started normally and the database status is abnormal.[Grid @ dtydb4 ~] $ Srvctl start service-d epmdb-s srv_epm1-I epmdb1PRCR-1013: Failed to start resource ora.

UnlockAlter user scott account unlock; Set PasswordAlter user scott identified by m123; LoginConn scott/m123; DisconnectDisc Change PasswordPassw Description of current userShow user  Connection commandConn system/manager (switch user)Disc is

Oracle 11g alert file changes Oracle 11g log files (somewhat changed) starting from Oracle 11g, Oracle provides Alert logs in XML and traditional text formats. The new log location is determined by the Automatic Diagnostic Repository (ADR. You can

Oracle character set:1. Solve the client issues temporarily. (Set the current environment variable to the same language as the system. Take oracle as the standard .) View the oracle Character Set SQL> select userenv ('language') from dual; USERENV ('

Oracle built-in IO test package dbms_resource_manager.CALIBRATE_IO oracle 11g started, launched the built-in IO test package, the principle is basically the same as the above mentioned Orion tool. Here is an example of specific use SQL> select group_

Some Oracle optimization experiences have not been optimized before in the project. Now I want to write down some of my experiences and hope I can remember them and help others. 1. tablespace management. A tablespace is the logical division of a

Oracle practice commonly used SQL TableA columnA columnB A 1 & 2 sss select * from A where columnA like '% 1 & 123456'; ------------------ prompt to enter A variable. What if I want to query sss Based on the clomnA value? Analysis: & is a variable