Database Administrator

V $ database: database information, such as the database name and creation time. V $ instance information, such as instance name and start time. V $ parameter information, select * from v $ parameter where name like '% name' ----> show parameter

Super User problems: Use admin # Adding or modifying user passwords Db. addUser ('admin', 'pwd ') # Viewing the user list Db. system. users. find () # User Authentication Db. auth ('admin', 'pwd ') # Deleting a user Db. removeUser

71. your database instance is started using the server parameter file (SPFILE ). control files are multiplexed and stored on different disks. because of a disk failure, you lost one of these control files. you replaced the damaged disk. what is the

The SQL statement is as follows: Select * from LOAN_BACK_LIBRARY where LIBRARY_ID = 1 or LIB_ID = 1 and STATUS = 3 The conditions for my desired results are:1. LIBRARY_ID = 1 or LIB_ID = 1 2. STATUS = 3 But this is not the case. STATUS is displayed!

1. view the size of all tablespaces SQL> select tablespace_name, sum (bytes)/1024/1024 M from dba_data_files group by tablespace_name; 2. Used tablespace sizeSQL> select tablespace_name, sum (bytes)/1024/1024 M from dba_free_space group by

1) Background: Recently, an Oracle10g RAC dual-node experimental platform was built in vmware and oracle RAC was upgraded from 10.2.0.1 to 10.2.0.5. Later, it was found that the two linux systems often restarted automatically; 2) platform

In hibernate, the object class is queried using hql statements, and the returned result of the list method is a List. The objects encapsulated in the List are divided into the following three situations:1. When you query all fields, such as "from

Use of the Oracle 10g wmsys. wm_concat row and column conversion function:First, let's take a look at this magic function wm_concat (column name). This function can separate the column values with "," and display them as a row. Next, let's take an

When we write SQL statements, we often ignore some details. The following is a summary of my own operations and materials. If there is something wrong or something wrong, hope to reply to me and learn from each other. Thank you!1. When a full table

1. Set this column to null and modify its type (this will cause data loss) 2. The simplest method:Assume that your table is named tab_target.Create table test as select * from tab_target whre 1 = 2;Alter table test modify (col_name number (5

MongoDB is a NoSQL database system. A database can contain multiple collections, each of which corresponds to tables in a relational database; A set of records identified by columns can be stored in each collection, and columns can be freely defined

The Table name and Schema name are the same: The schema and table names are both Arwen.Schema Arwen contains a PKG package with the Plus function. The result of adding two numbers is returned.SELECT Arwen. PKG. Plus (1, 2) FROM dual; -- no error

Install the Oracle client software:Root Account execution:# Groupadd oinstall# Groupadd dba# Useradd-g oinstall-G dba oracle# Passwd oracleCreate an oracle basic directory:# Mkdir-p/u01/app/oracle# Chown-R oracle: oinstall/u01# Chmod-R 775/u01/U01

Oracle 11.2.0.2 has many bugs.Many databases have encountered problems after being migrated to Oracle 11.2.0.2.Two Oracle 11.2.0.2 problems are being resolved:ORA-00600: internal error code, arguments: [ktecgsc: kcbz_objdchk], [0], [0], [1], 2. This

1. When LGWR is idle, it will check whether any data is written from redo buffer to redelog every 3 seconds. If yes, a background process will automatically write the data into it. 2. When a process needs to allocate space from the redo buffer, the

1.Function 1) Create a function Create or replace function get_tax (x number) Return number Begin Declare y number; Begin Y:=X-2000; If x= 0 then Return 0; End if; Returns y * 5/100; End; End

MongoDB has three methods to save java objects. One is to implement the DBObject interface through a class, and the other is to use the object ing function of the spring-mongodb tool, converts a java object to the BSON document of MongoDB. One is to

About GoldenGateOracle Golden Gate is a log-based copy and backup software for structured data. It parses online logs of the source database or archive logs to obtain incremental data changes, apply these changes to the target database to

The most typical application of Database Synchronization is Remote Disaster Tolerance and the query statistics of the primary database. This is generally a one-to-one application. However, the demand for multi-dimensional synchronization sometimes

Oracle Server modifies Character Set and uses dba user to log on 1. view the character set of the current serverSelect userenv ('language') from dual; 2. Shut down the databaseShutdown immediate; 3. Start to MountStartup mount; 4. Session