• Summary of Oracle common views


    1. Dynamic performance view of database / instancev$database :displays information about the database from the control file.V $instance: displays the state of the current instanceV $option: displays Oracle database options and features        Option must be separately licensed        whereas features come with the product and are enabled based on         The product that is runningv$parameter :displays information […]

  • Oracle clear waterline without data table


    *: Oracle uses delete to clearly represent the high water mark left after the information ①.alter table tablename enable row movement;②.alter table tablename shrink space;   Truncate table can automatically clear the high water mark To be verified

  • Oracle create database and user, table space, manage table space and data file


    introduce A table space is a logical part of a database Physically: the database data is stored in the data file Logically, the database is stored in the table space A table space consists of one or more data files   Logical structure of database Introduction: Logical structure in Oracle includes table space, segment, zone, […]

  • descriptive flexfield


        1、 Descriptive elastic domain Foreword introduction: The essence of descriptive elastic domain is that the system reserves self-defined fields, and the system can use descriptive elastic domain to obtain important additional information unique to the business. The system may customize the descriptive elastic field to display the fields that store more information, and […]

  • Oracle ultimate complete uninstall


    1、 Stop usingOracleOur services Out of serviceoracleService, access to computerManagement, in the service, find oracleAll services at the beginningRight click to select stop.   2、 Open the universal installer tool and run the program to uninstall Oracle database (1) General operationOracleBuilt in uninstall program, such as using Universal Installer Tool uninstall. clickopening menufindOracle,Then clickOracleInstall products,Click againUniversal […]

  • Oracle initial (day 1)


    1、 Database classification 1. Small database: access, FOXBASE 2. Medium sized databases: Informix, SQL server, MySQL 3. Large databases: Sybase, DB2, Oracle 2notes   1./* November 6, 2020 This is a multiline comment in Oracle   */ 2. — this is a single line comment for Oracle   3、 Common commands 1. Data type (1) Character type: […]

  • Common functions and tools of Oracle


    1、 Brief introduction of the author First of all, I would like to introduce myself. In my traditional work, the author basically used Oracle in the first year, and the technology was very backward, but there was no way. At that time, my strength was really weak, and I needed to hone, and I also […]

  • Oracle (day 2)


    1、 Foreign key: constraint, references For example: SnO number (7) constraint fk_ sno references student(sno),   2、 Delete (all DDL statements) drop table; Delete the table structure and the data in the table( (delete table) truncate table; Delete the data in the table and keep the table structure( (truncated table)   3、 Index   1. […]

  • Oracle (day 3)


    1、 Delete: a DML statement. Delete the data with specified conditions in the database Delete from table name where a = B( Conditional deletion) Delete from table name; Delete the data of all rows. You cannot delete the value of a column. After executing the statement, you need to commit to reflect it in the […]

  • Oracle (day 4)


    1、 Distinct Syntax format: select distinct column name from table name 2、 Statistical function avg(x) count(1) count(*) max(x) min(x) sum(x) StdDev (x) to find the standard deviation of the value of X in a group of rows Variance (x) find the variance of x value in a group of rows Round and TRUNC: select round(avg(sal),4) […]

  • Oracle (day 5)


    Subquery 1. Single line subquery: For example: select * from EMP where Sal > (select Sal from EMP where ename =’allen ‘); 2. Multi row subquery: any all in Greater than any is greater than the minimum   select * from emp where sal>any(select sal from emp where deptno=10);   select * from emp where sal>(select min(sal) […]

  • Solutions to prompt “insufficient privileges” in Oracle login


    After installing Oracle, open SQL plus   After logging in and entering the user password(even if you confirm that there is no error in Oracle installation, or you reload several times, and the user name and password are completely correct, you can’t do it!) ① Solution 1: Modify the local user group information to solve […]