Oracle

The Sys_connect_by_path function in Oracle is a very important function, and here is an example of using the Sys_connect_by_path function, as follows:Data preparation:1 Create TableTest (Avarchar2(Ten), bvarchar2(Ten)); 2 3 INSERT intoTEST (A,

Many application scenarios, in order to prevent the occurrence of disasters, to protect against the loss of important data, remote disaster recovery solution level is not poor. Then the database will undoubtedly become the focus of the protection of

A study think three knocks to understand, can long-term effective memoryWhen I first learned Oracle, we learned about Oracle's advantages, such as distributed management, easy coordination, superior performance, support for big data formats, and the

Statement:ALTER TABLE tableName Rename column oldcname to Newcname; --Modify field namesALTER TABLE TableName Modify (cloumnname data type); --Modifying data typesFor example:1. Create a table:CREATE TABLE Student (ID VARCHAR2 (+) primary key,Name

The charset set in the client under Oracle should be consistent on the server, otherwise garbled, and Oracle's client can be controlled by the environment variable Nls_lang under the Windows/dos System or UNIX system, and the operation is simple,

To query all table spaces in the library:Select Tablespace_name from Dba_tablespaces;Select Tablespace_name from User_tablespaces;Query the table space used:Select distinct tablespace_name from Dba_all_tables;Select distinct tablespace_name from

Create or Replace procedurePrc_table_count (P_flag outvarchar2) asTCOUNT Number; Scount Number; CountsqlVARCHAR2( -);BEGINTCOUNT:= 0; Scount:= 0; forC_rowinch ( Selecttable_name fromSYS. User_tab_comments TWHERET.table_name like 'zzjg%') LOOP

Actually length and vsize these twofunctionThe connection is not big, the difference is great. Although it is all "fetch length", but lengthfunctionThe result is "how many characters", vsize The result is "how many bytes are needed".Simply look at

1. Oracle ORCL VSS writer service:oracle volume map copy write serviceVSS (Volume Shadow copy Service) enables you to create a high-fidelity point-in-time image of a storage infrastructure (such as a disk, array, and so on), which is a mapped copy

Oracle's EXP/IMP command is used to implement export/import operations to the database; the EXP command is used to bring data from the remote database server to the local, generating a. dmp file; The IMP command is used to import local database. dmp

Oracle executes external files:C:>sqlplus user/[email protected]sql> @new. sqlExecute multiple SQL files:1. Place all the files in the same directory and execute the command at the command line:c:>dir/b > D:/1.sqlAll the SQL file names are exported

Differences in Oracle (+) usage with LEFT joinOriginal January 11, 2017 13:33:42 6648 SELECT * from a b where a.id=b.id (+);(+) written in the back of where, not with or/in,Table B is an accessory table.------------------------------

Test forms using the Oracle database:--single-Table query data Syntax Select (query) * All/query fields, multiple fields, separating from table name--find information for all employeesSelect * fromscott.emp;Select * fromDept;--query all employee

--View tablespace names, path, size, and usage of data filesSelect B.tablespace_name "tablespace name",B.file_name "Data file path",b.bytes/1024/1024 "Size (M)",SUBSTR ((B.bytes-sum (NVL (a.bytes,0))/(b.bytes) *100,1,5) "Utilization"From

/*divided into four steps*//*1th Step: Create a temporary table space*/Create Temporarytablespace slfph_temp tempfile'D:\oracledata\slfph_temp.dbf'size 50m Autoextend on Next50m maxsize 20480m extent management local;/*2nd Step: Create a data table

1C:\users\administrator>sqlplus Sys/[email protected]/ORCL as Sysdba2 3Sql*plus:release 11.2.0.1.0 Production on Saturday December 16 03:51:28 20174 5Copyright (c) 1982, 2010, Oracle. All rights reserved.6 7 8 Connect to:9Oracle Database 11g

1 Status queries Start state SQL Statement Results Nomount Select status from V$instance; STARTED Select Open_mode from V$database; ERROR at line 1:Ora-01507:database not mounted

Pseudo- column: a pseudo-column in Oracle is like a table column (a column in a table), but it is not stored in a table, a pseudo-column can be queried from a table, but its values cannot be inserted, updated, or deletedCommon pseudo-Columns are

Oracle database instances and servicesA. instances and databases 1. instance: A group of Oracle background processes/threads andShared Memory ZoneThe memory is shared by threads/processes running on the same computer. An instance is used to manage

Explanation of the use of Translate in Oracle and DB2 databases, db2translate I. Oracle Syntax: Translate (string, from_str, to_str) Eg: select translate ('abcdef', 'abf', 'cde') from dual; Result: Move 'abf' in the 'abcdef' string to 'cde ') 2.