Oracle

two ways to connect Oracle databases: Dedicated server connections and shared server connectionsOne, the Oracle database consists of:Oracle server is comprised of: instances and databases;Oracle database consists of: Data file redo log file

Oracle Flash back query and flash back databaseDifference:For data flashback queries, you only need to enable the Undo table space to automatically manage rollback information.Using the flashback removal technology and the Flashback database

Conclusion: Using the Imp tool is unable to implement the existing data in the Overwrite table, it is said that using Impdb's table_exists_action=truncate option canWhen importing data with Imp, without special parameters, if the table already

Creating and managing Table spaces1. Create a table Space exampleSelect name from V$datafile;Sql> select name from V$datafile;NAME--------------------------------------------------------------------------------/u02/oracle/oradata/orcl/system01.dbf/u0

Typically,the ORACLE_SID environment variable is the full name of the ORACLE System Identifier, which is used to identify different instances on a single server, by default the instance name is Oracle_ The value of the SID (that is, Instance_name=

People who work with Oracle use a variety of tools to connect to Oracle databases on a daily basis, such as sql*plus, PL/sql, TOAD, Sqldeveloper, and so on, listing several ways to connect to Oracle, in this case sql* Plus, for example.1. Easy

201705251537Trcsess.awk tool, use similar to the following:Awk-f Trcsess.awk xxx.trc > Xxx.more1615Tvdztat-i .... trc-o xxx.html201705261604Select T1.pname,t1.pval1,t1.pval2 from sys.aux_stats$ t1where t1.sname= ' Sysstats_main ';Select sum (t1.

1. Run Sqlplus toolC:\users\wd-pc>sqlplus2. Go directly to the Sqlplus command promptC:\users\wd-pc>sqlplus/nolog3. Connect as OS IdentityC:\users\wd-pc>sqlplus/as SYSDBA orSql>connect/as SYSDBA4, Normal User loginC:\users\wd-pc>sqlplus scott/123456

Oracle database, data increment, delete, change, check, through SQL statement implementationSQL: Structured Query language;Features: Case-insensitive, string enclosed in single quotation marks, end of statement end with semicolon;Line comment, add "-

/*The grouping function can no longer have normal columns in the SELECT clause, unless the column gives all the null values in group by to be grouped into a group filter SELECT from WHERE GROUPBY having an by-clause*/--find out the average salary

If the character encoding of Oracle is GBK, then a Chinese character takes up two bytes, but if you use UTF-8, then a Chinese character occupies three bytes. The VARCHAR2 type is used in most cases to ensure better compatibility.GBK Character Set:

                                                                Oracle Create user and permissions settingsPermissions:Create sessionCREATE tableUnlimited tablespaceConnectResourceDbaCases:#sqlplus/nologSql> Conn/as sysdba;Sql>create user username

1 One:2 Select * fromDba_profiles swhereS.profile='DEFAULT' andResource_name='Password_life_time';--viewing user password time limits3 ALTERProfiledefaultLimit Password_life_time UNLIMITED;--set to Unrestricted4 5 Two:6 SELECTUsername,profile

Display partition table informationDisplay information for all partitioned tables in the database: Dba_part_tablesDisplays all partition table information that the current user can access: all_part_tablesDisplays information about all partitioned

Stored Procedure creation Syntax:Create or Replace procedure stored procedure name (param1 in type,param2 out type)AsVariable 1 type (value range);Variable 2 type (value range);BeginSelect COUNT (*) into variable 1 from table A where column name

--1, the following are related tablesSELECT * from V$lock;SELECT * from V$sqlarea;SELECT * from V$session;SELECT * from V$process;SELECT * from V$locked_object;SELECT * from All_objects;SELECT * from v$session_wait;--2, viewing locked tablesSelect B.

Sequence: is a database object provided by Oacle to produce a series of unique numbers. Automatically provide a unique value Shared objects Primarily used to provide primary key values Loading

First, view the table in the Recycle BinSelect Object_name,original_name,partition_name,type,ts_name,createtime,droptime from RecycleBin;Second, the recovery tableSql>flashback table Test_drop to before drop; Sql>flashback table

Sequence: is a database object provided by Oacle to produce a series of unique numbers.L automatically provide a unique valueL Shared objectsL mainly used to provide primary key valueL Loading sequence values into memory improves access efficiencyTo

/*$SQL: SQL statements$pagedir: Paging Click to jump Address$page Current PageTotal $count Data$pagesize show the number of bars per page*/Function page ($sql, $pagedir, $page = 1, $count, $pagesize = 10) {$pagecode = ";$page = Intval ($page);$count