Oracle

I. Use of SQL1. IN OperatorSQL statements written IN are easy to write and understand, which is suitable for modern software development.However, SQL statements using IN always have low performance. The following differences exist between SQL

  Basic query:   View plain -- Query Information of all employees Select * from emp; -- Set the row width Set linesize 120; -- Set the column width to the width of four digits Col empno for 9999; -- Set the column width. a indicates the string

  The SQL language has two components: DML (data manipulation language): They are SELECT, UPDATE, INSERT, and DELETE, just like their names. These four commands are used to operate the data in the database. DDL (data definition language): DDL is

  In the R & D center, a database running oracle and sqlserver on Windows is an old machine with three hard disks attached, however, I recently received a request from my colleague saying that the disk where the oracle database data file is located

The prerequisite for ORACLE's information lifecycle management tool ILMA is Apex.Apex is installed by default in oracle 11g Release 2. It is not enabled after installation. You can use the following method to enable it.SQL> show userUSER is "SYS"SQL>

1. Combination of LOOP and IF in loop LOOP CasesDeclareX number;BeginX: = 0;Loop -- start of loopX: = x + 1;If x> 3 then -- cyclic bodyExit;End if;Dbms_output.put_line ('value of inner x '| x); -- cyclic bodyEnd loop; -- end loopDbms_output.put_line

Author: skateTime: 2010-08-20   Table join   Table join refers to the association between tables in an SQL statement to retrieve relevant data from one or more tables. If an SQL statement has more than two associated tables, So what is the order of

Common Sqlplus commands are as follows: 1. login system user:Sqlplus and then enter the system user name and password Log on to another user:Conn user name/password;  2. Create a tablespace Create tablespace space name Datafile 'C: "Space name' size

IMP-00003: solution to ORACLE error 959 ORALCE 11G X64 is the most common Import and Export method. IMP-00003: ORACLE error 959ORA-00959: tablespace 'xxxxxxxxxxxxxxxxx' does not exist. I did not pay attention to it before, but lost several tables. I

Summary of Automatic startup of Oracle Database on Solaris: 1. Automatic startup of Solaris on Solaris will automatically run/etc/rc. all scripts in the d directory. The larger N, the higher the execution level. The script starting with S runs

In oracle, the content of each control file is the same. A control file records the physical structure of the entire database. It contains the following information: 1. database Name 2. file Name and path of the data file and redo log file 3. for

Configure tnsnames for the local oracle NET service name. oracle local NET service name configuration tnsnames. the ora file has strict format requirements. Today, a service name is manually added to the configuration file, and the service_name

DECLARE iCount number (2): = 0; begin select count (*) INTO iCount FROM user_sequences u WHERE u. sequence_name = 'seq _ TCAPITALNOTIFY '; www.2cto.com IF iCount = 0 THEN/* create sequence */execute immediate 'create sequence SEQ_TCAPITALNOTIFY

Differences between the Oracle optimizer CBO and RULE 1. When the Rule-Based Optimization (RBO) optimizer analyzes SQL statements, oracle rules are followed and are not sensitive to Data. It uses only a small amount of information to determine the

Environment: the database is in Open state, then rm-rf users. dbf (delete users tablespace), and finally retrieve the users. dbf file. When replying, the reply method has little to do with the database version (because it is a physical file), but

Oracle converts the table name and field name to uppercase. When using powerdesigner to create a database, pay attention to Case sensitivity. Note: The following scripts are correctly executed on oracle 10g and 11g to convert table names to

Oracle note (7) data update, transaction processing, data pseudo column 1. Data Update operations in the DML operation syntax, in addition to queries, there are also database update operations for data, the data update operation mainly refers to

One simple health check for oracle with SQL There are some sqls which is used for check the oracle database's health condition. [sql] ------numbers of process [sql] select count(*) process_num from v$process; [sql] select

Date-related operations are currently used. 1. Obtain the date of the current week and Monday. select trunc(sysdate, 'yyyy') - to_char(trunc(sysdate, 'yyyy'), 'd') - 5 + (select to_char(sysdate, 'ww') from dual) * 7 startweek from dual;  2.

In LINUX, you have written a script before using crontab to perform the RMAN backup experiment. You can run it manually. You cannot run it successfully using crontab. This afternoon, we spent two hours experimenting with the following: Note: after