Oracle

0. Common functionssubstr(str,start,length);//可以反向索引。length不指定就到结尾to_number(str);//str转numberselectto_char(sysdate,‘yyyy-mm-dd hh24:mi:ss‘) from dual;//日期转字符nvl(tt,0);//若是空值则为01. CursorsFor the processing of collection data, learn how to use

First, Oracle materialized view syntaxCreate materialized view [view_name]Refresh [Fast|complete|force][On [Commit|demand] | Start with (start_time) next (next_time)]As{Create a query statement for materialized views}These are the syntax commonly

I. Oracle DATA dictionaryA data dictionary is where Oracle stores information about a database and uses it to describe the data. For example, the creator information of a table, create time information, the table space information, user access

EXP Export Environment:Oracle Database 11g Enterprise Edition Release 11.2.0.1.0-64bit ProductionSql> SELECT * from nls_database_parameters where parameter= ' nls_characterset ';PARAMETER VALUE------------------ ----------Nls_characterset

Reprinted from: http://www.cnblogs.com/sopost/archive/2010/08/14/2190098.htmlConfiguring EM with EMCAEMCA is a command prompt that uses formats and methods to enter EMCA at a command prompt, EMCA use help appears on the screen.Command Help is as

There is an external network of the environment table space is seriously insufficient, customers do not want to expand, to clean up part of the data, are large pieces of blob. Table space is 1T, already using 0.99T, deleted before 2015 blob, through

Absrtact: Database performance problem has always been the focus of decision-makers and technical staff, an important factor affecting database performance is the inefficiency of SQL query statement, and the use of multi-table join query in SQL

Different versions of the database direct this function return type inconsistency causes a program mapping error:1. Error message:cause:java.sql.sqlsyntaxerrorexception:ora-01790: An expression must have the same data type as the corresponding

Impdp/expdp To create a logical directory, the command does not create a real directory in the operating system, preferably created by an administrator such as system.Create directory Dpdata as '/opt ';Second, view the Management Manager directory

drop table example; CREATE TABLE Example (ID number (4) Not NULL, NAME VARCHAR, constraint example_id primary key (ID));d ROP SEQUENCE example_sequence; CREATE SEQUENCE example_sequenceincrement by 1--add several start with 1 each--starting from 1

Oracle SQL Developer connection MySQLOracle SQL Developer is a very powerful open-source SQL development tool , but recently I began to study it , just installed oraclesql Developer is not supported for MySQL connection,need to from Download the

If the Oracle database Time field is set to "number" type, the query time column will be displayed as a numeric value, such as "1241450728000" style, not readable, and if "2009/5/4 15:25:28 "The style update time will prompt" Ora-01722:invalid

Comparison:Plsqldev: Third-party, fast startup software, slow execution of SQL queriesSqldeveloper:oracle company, slow startup software, fast execution of SQL queriesObjective:To connect a local Oracle Server service-side instance using

Oracle Database 10g Release 2 (10.2.0.1.0) Enterprise/standard Edition for Microsoft Windows

Oracle Database Migration-FundamentalsAs a developer, database knowledge must be in our hands. But now the company's database is dedicated DBA maintenance, usually give us an environment address, and then we write Crud SQL. And the company's product

About audits:11g By default, the auditing option is enabled, and the default value of the Audit_trail parameter is DB, which indicates that the audit data will be recorded on the sys.aud$ Audit Dictionary base table in the database. In Oracle 10g,

After installing the Oracle 10g R2 in CentOS 6.3, after rebooting, you will find that Oracle does not boot itself, which is normal, because the installation of Oracle under Linux does not start on its own, you must set the relevant parameters, First

Function: Oracle data import and export imp/exp is comparable with Oracle data restore and backup.In most cases, the data can be backed up and restored with Oracle data import and export (no loss of data).Oracle has a benefit, although your computer

AVG ([distinct|all]x) The "function" statistic table selects the average of row x columns. The "parameter" all means averaging all the values, distinct only the different values, the default is all if there is a parameter distinct or all, a space is

Oracle Database migration-BasicsOracle Database migration-Basics As a developer, We must master database knowledge. However, the company's database is maintained by a dedicated DBA. Generally, we provide an environment address, and then we write