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If you are trying to add a new Not NULL columns to a table and you get the following error: ORA-01758: table must be empty to add mandatory (NOT NULL) column Since the values in the new column are null (after all, you just added the column) the new constraint can ...

Oracle/PLSQL: NVL Function In Oracle/PLSQL, the NVL function lets you substitute a value when a null value is encountered. The syntax for the NVL function is: NVL( string1, replace_with ) string1 is the string to test for a null value. replace_with is the value returned if string1 is null. Applies To: Oracle 8i, Oracle ...

Oracle =========================================================== Books: Database Concepts ----------------------------------------------------------- Database Structure and Space Management ----------------------------------------------------------- Logical Database Structure * Schema/Schema object(the logical structures that directly refer to the DB's data a schema is owned by a user who has the same name as the schema) Table View Index Cluster * Data block * Extent * Segment * Tablespace Online(accessible)and Offine(not accessible) * Databse, TableSpaces, and Datafiles Physical Database Structures * Datafiles (the charateristics of ...

This is my study note about mysql :) MySQL ============================================== http://www.mysql.com Usages --------------------- System parameters *select version(),user(),current_date,now(); Install/Remove MySQL service *mysql -install|remove *net start|stop mysql (this command will not work if use mysqld --standalone) *mysqladmin -u root -p shutdown(it works in all status) Commands *Cancel the command \c Backup the data *mysqldump -u root -ppasswd user|othertable|--all-database>backup.sql Load the data from text file *load data local infile 'data.txt' ...

If you administer a busy database you will see this error from time to time. It is nothing to worry about, but it can be quite annoying when it stops you from doing something. It simply means that session has a lock on an object that your session is trying to ...

第一章：日志管理 1.forcing log switches sql> alter system switch logfile; 2.forcing checkpoints sql> alter system checkpoint; 3.adding online redo log groups sql> alter database add logfile [group 4] sql> (`/disk3/log4a.rdo`,`/disk4/log4b.rdo`) size 1m; 4.adding online redo log members sql> alter database add logfile member sql> `/disk3/log1b.rdo` to group 1, sql> `/disk4/log2b.rdo` to group 2; 5.changes the name of the online redo logfile sql> alter database ...

SQL*Plus — schemata — data types — DML & DDL examples — editing commands — using external files — the dual pseudo-table — introduction to transactions — optional exercise — references Introduction During this tutorial you will build on your databases knowledge by learning the fundamentals of Oracle, one of ...

A package is a group of procedures, functions, variables and SQL statements created as a single unit. It is used to store together related objects. A package has two parts, Package Specification or spec or package header and Package Body. Package Specification acts as an interface to the package. Declaration of ...

Begin for i in 1..10 loop insert into TABLE_NAME () values () ; end loop; end; commit;