Oracle

Oracle "CONNECT by" is a hierarchical query clause that is typically used for queries of tree or hierarchical result sets. Its syntax is: [ START WITHcondition ] CONNECTBY[ NOCYCLE ] condition Description1. Start with: Tells the system which node to

/* The following command checks the step--1 when running the */--task in Sql*plus without execution. Check if the instance session is restricted select Instance_name,logins from v$instance;-- If prompted logins=restricted perform the alter system

I. Transactions and stored ProceduresHow transactions are used in a stored procedure. When you need to execute multiple additions, modifications, and deletions of SQL statements in a stored procedure, we need to use transactions to ensure data

1. Eliminate duplicate rowsIn the results of an Oracle query, there may be several rows in the same situation, so you can use distinct to eliminate duplicate rows.Code Demo: Distinct eliminate duplicate rows2. Null operationIf there is a missing

An inner join (inner join), an outer join (outer join) has been learned in SQL Server, and an outer join is divided into a left outer join (outer join) andRight outer join (outer join). An outer join between two tables or several tables in Oracle is

Oracle MySql[Java] Driver&url for Oracle and MySQL

In the previous blog examples, we created a function-based index, but if you execute the following query:select * from EMP where substr (ename,1,1) = ' S ';The resulting execution plan will still be (TABLE ACCESS full) because the function-based

When you parse a partitioned index with the parse command, the range information for the data values for each partition is placed in the Oracle data dictionary.Oracle can use this information to extract data partitions that are only related to SQL

These articles of Oracle Performance optimization operations can be used in conjunction with each other. And the various methods of interaction, close contact.This connection is both consistent and may bring conflict, when the conflict occurs, the

Oracle Learning website http://www.oracle-base.com to get a sense of the article, thatOracleThe basic skills are very solid. (English)http://asktom.oracle.com/pls/apex/f?p=100:1:0 ; mainly experts to answer questions of the site, biased to improve

One, a stored procedure with a cursor　　There are two types of cursors as arguments:　　1. Declaring the system cursor type Sys_refcursor1) The cursor acts as a parameter to the stored procedure:--stored procedures with cursorsCREATE OR REPLACE

One. The SQL language supports the following categories of commands1. Data definition Language (DDL): Create, Alter (change), and drop (delete) commands1.1 Create (creating tables, table spaces, users, indexes, views, synonyms, procedures,

Recording type (learning notes), recording type learning notesDefine record type TYPE name is record (member name data TYPE [[not null] [: = default value] expression],... member Name Data Type [[not null] [: = default value] expression]); Example 1,

Create and call functions and stored FunctionsFunction [in out parameter] -- Function [in out parameter] create or replace function get_test (m_id in number, str1 out varchar2) -- The parameter does not need type length return varchar2 is str2

Oracle performance optimization operations: Summary These articles about oracle performance optimization can be used in combination with each other. In addition, various methods are closely related to each other. This kind of connection is

Steps for creating a quick and manual Oracle10g Database0. Modify Environment Variables[Oracle @ ocm1 ~] $ Vi. bash_profileAdd the following content: export ORACLE_SID = PRODExport ORACLE_BASE =/u01/app/oracleexport ORACLE_HOME = $

Package (study notes) and study notes Example 1,Locate all employees in the department according to the entered Department number. First, create a package and define the package specifications. Create or replace package getemp_pkg is FUNCTION

Oracle11gRMAN: ActiveDatabaseDuplicationforstandbydatabaseIf the production-based duplicate replication is not manually configured with pfile (set memory, process, dg-related configuration parameters, database-related path parameters), various

Function (learning notes), function learning notes Function (storage function)It is also a convenient storage structure. User-defined functions can be directly called by SQL statements or PL/SQL. The biggest difference between a function and a

Oracle Performance Optimization Operation 10: decomposing complex queries and replacing variables with Constants For complex Where condition combinations, Where contains multiple indexed fields, use the IF statement to discuss the situation; At