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Today, I encountered a problem when I was doing database restoration. I had two backup sets under the directory. I wanted to specify a backup set for restoration. I checked the information and made a simple experiment record: RMAN> run {2> allocate

Today, I encountered a problem when I was doing database restoration. I had two backup sets under the directory. I wanted to specify a backup set for restoration. I came back and checked the information. Next I will do a simple experiment. Today, I

RMAN Specifies backup set recovery Today in the database restore time encountered a problem, that is, there are two of directories below the backup set, to specify the backup set to restore, back to check the data, the following do a simple

1: List all employees ' names, department names, and wagesSelect A1.ename,a1.sal,a2.dname from emp a1,dept A2 where A1.deptno = A2.deptno;2: List details of all departments and number of departmentsSelect A2.deptno,a2.dname,a2.loc,count (a1.empno)

First episode:#目前主流数据库 Microsoft Sqlsever and access MySQL ad2 Sybase informix Oracle #小型数据库: Access: Less than 100 people with low security requirements #中型数据库: Mysql,sqlsev ER: Load at 5000 to 15000 #大型数据库: sybase,oracle,db2: Load can handle

Create a tableSql>create Table Classes (ClassId Number (2),CNAME varchar2 (+) ,Birthday Date);Add a fieldsql>alter Table Student Add (classId number (2));Modify field lengthSql>alter Table Student Modify (XM VARCHAR2 (30));Modify the type of the

These are all relatively basic, or a refresher.A simple query statement1. Query table structureSQL>DESC Dept; ( a command window is required to use this statement when using a PL/SQL developer Query )2. Query all ColumnsSql>select * FROM Dept;3.

Oracle Complex Query Data Group, Grouping FunctionsMax, Min, AVG, sum, count Query the name of the person with the highest salary Select ename from EMP where sal = (select max (SAL) from EMP ); Salary increases by 10% for all employees lower

Data grouping,grouping function max, min, avg, SUM, Count Find the name of the person with the highest pay Select ename from emp where sal = (select Max (SAL) from EMP); 10% increase in salary for all employees below average

Without the standardization process involved, it is very difficult for programmers to develop an application that can be used in a variety of languages. If possible, the translation process can be done in the database, so that developers have a lot