Oracle

single-line function : Only one parameter input, only one result outputMultiline function or grouping function : can have multiple parameter inputs, only one result outputTest lower/upper/initcap function, use dual dummy tableSelect lower ('

--XmlElement multiple label levelsSELECTXMLELEMENT ("TEST", XMLELEMENT ("AA", XMLELEMENT ("BB" ,'XXX'), XMLELEMENT ("CC",'XXX'))) fromDUAL; SELECTXMLELEMENT ("test") fromDUAL----xmlattributes Multiple PropertiesSELECTXMLELEMENT ("TEST",'123',

1. Oracle memory is composed of SGA+PGA2. Oracle Database ArchitectureDatabase architecture refers to the composition, working process and principle of database, and the organization and management mechanism of data in database.How Oracle Works:1),

Assuming that this is page pageno, there are pagesize records per page, and now the student table is queried using MySQL, Oracle, and SQL Server paging.1. mysql Paging query:1 SELECT 2 * 3 from 4 student5-1* pagesize,pagesize;Understanding:

ObjectiveEach table has a primary key, which can be a simple primary key and a combined primary key, a simple primary key is a column in the table, and the combined primary key is a few columns in the table. There are many types of primary key

Fortunately, on-line, there is no dual database, you can try to use the Select function without the from data table to implement the return value.Some test code:Try: Conn= Psycopg2.connect (Database=db.service_name, User=db.username,

Recently, a simple study of the data paging query of oracle,mysql,sqlserver2005 has been made, and the statements of each query are posted for everyone to learn. (a), the MySQL paging query MySQL paging query is the simplest, with the help of

Requirement: Insert data in Gisdata table, if WXID data exists on update, does not exist insertMyBatis configuration for MySQL1 XML version= "1.0" encoding= "UTF-8"?>2 DOCTYPE Mapper Public "-//mybatis.org//dtd mapper 3.0//en"3

http://oracle-internals.com/blog/links/http://coll15.mapyourshow.com/6_0/sessions/session-details.cfm?ScheduleID=5410LinksI ' ve compiled a list of links to sites containing oracle-related information. Internals-related Links

(1)Select the most efficient table name order (valid only in the rule-based optimizer):The Oracle parser processes the table names in the FROM clause in a right-to-left order, and the FROM clause is written in the final table (the underlying table,

Problem descriptionIn order to add a table in Oracle, build a table in PDM, use its generated SQL statement, but the build table cannot succeed, prompt ORA-00906: missing opening parenthesisThe reason is more clustered keywordScenario Replay1.

Packageutil;ImportJava.io.BufferedReader;ImportJava.io.BufferedWriter;ImportJava.io.File;ImportJava.io.FileReader;ImportJava.io.FileWriter;Importjava.io.IOException;/** * @authorWyl * @Description TODO * @date 2016-5-19 **/ Public

1. Download the Oracle 11g R2 for Windows version, the official website is as follows:Http://download.oracle.com/otn/nt/oracle11g/112010/win32_11gR2_database_1of2.zip　Http://download.oracle.com/otn/nt/oracle11g/112010/win32_11gR2_database_2of2.zip2.

Oracle Learning NotesAnalysis of SQL statement execution Process lecturesThis lesson goes into the database by telling a SQL statementand its entire execution process in the databaseString The architecture inside the database.Let's take a closer

Oracle OCP Notes (31) using the Flashback featureOracle's flashback feature is supported by one of 3 database architectures: Undo data, Flashback recovery area, and Recycle Bin.Undoing data in the undo Tablespace not only supports transaction

The SQL statement executes the complete process:1. The user process submits an SQL statement: Update temp set A=A*2 to the server process.2. After the server process receives the information from the user process, the process allocates the required

I. Overview of database ManagementAfter completing the Oracle Software installation, the DBA should be responsible for organizing and managing the database, with the main tasks of:(1) Start and close the database;(2) Create a database;(3) Delete the

Toss it several times, experience is:Installation of the packageIn the installation package, the development of the installation package must be installed.In addition, after the installation is complete, the packages that need to be installed

Brief introductionSAP claims that Hana is the fastest database, so SAP's new ERP system S4 no longer supports OracleA new feature of Oracle 12c is the ability to convert between rows and columns for the same tableSAP wants users to think of Hana as

Introduction to commonly used string aggregation (concatenation) functions1.WMSYS. Wm_concatStarting with Oracle 10G support, using the following examples:Select Deptno,wmsys.wm_concat (ename)From EMPGroup BY Deptno;To change the delimiter between