Database Administrator

Add Constraints SQL> alter table customer add constraint cardunique unique (cardId ); Delete Constraints SQL> alter table customer drop constraint addresscheck; When deleting a primary key, the cascade option must be included. SQL> alter table

When you install or use cx_Oracle, you need to use the connector El library, such as libclntsh. so.10.1. Otherwise, there will be various error messages. After installing the Oracle Instant Client, you can get this link library to Avoid installing a

1. installation: Create bea group and weblogic usersUse root to log on to the operating system and run the following command to create the bea group and weblogic users. Bea group number is 600, weblogic user number is 600, belongs to the bea group,

After logging on to https: // localhost: 1158/em, you can see that the database instances are all closed and cannot be started. Find a solution on the Internet and write it down. Enter dos (1) view the dbconsole status: emctl status

1. about connecting to the Oracle database ①, Normally connected to generate the database Of course, you must connect to Oracle before creating a database. 1. First select the DataBase type: DataBase ---> Choose DataBase: 2. Establish a connection:

1. Create a database:Create database database_name;Two methods for creating a database in php: mysql_create_db (), mysql_query ())$ Conn = mysql_connect ("localhost", "username", "password") orDie ("cocould not connect to localhost ");1.Mysql_create_

Question: Why is transaction introduced? 1>. Data Integrity 2>. Data Security 3>. Make full use of system resources to improve the system's concurrent processing capability 1. Transaction Features Transactions have four features: Atomiocity,

Sometimes we need to modify the sid and dbname of the database. In addition to using rman for backup and recovery, we can also manually modify it, mainly through two main processes:1. Modify the Instance name (SID)2. Modify the Database Name (dbname)

I learned about Oracle Table Partitioning and object-relational database system. 1. oracle partitioning Oracle partitions are introduced in oracle 8.0. This process physically breaks down a table or index into smaller and more manageable parts. In

1. USERENV (OPTION)Returns the current session information.OPTION = 'isdba ': TRUE if the current role is a DBA; otherwise, FALSE.OPTION = 'language' returns the character set of the database.OPTION = 'sessionid' is the current session

Today, I encountered a lot of problems when installing the MySQL stress testing tool sysbench. Although there are many installation examples on the Internet, they are not accurate enough, or they are not very similar to my own environment, as a

Download and install navicat 9.0 Premium (Advanced English version) and connect to mysql normally. We can see that it supports both Oracle, sqlite and postgresql, and want to connect to oracle for centralized management. 1. However, a listener error

The default "wait_timeout" of the MySQL server is 8 hours (that is, the default value is 28800 seconds). That is to say, if a connection is idle for more than 8 hours, MySQL will automatically disconnect the connection, in general, a connection is

Oracle10 Client installation 1. First, go to www.oracle.com to download oracle10g linux client name 10201_client_linux32.zip. Size: 467 M. Register and download it. 2. because I am using Remote Installation, and I do not use remote operations like

Use the following code in java to query the clob column of db2 (Conn. createStatement (ResultSet. TYPE_SCROLL_INSENSITIVE, resultset.concur_read_only1_cmd.exe cuteQuery (SQL)The following error is reported: DB2 SQL error: SQLCODE:-270, SQLSTATE: 42

(1) There are a lot of help information prompts in Oracle. How can we query such help prompts? You can use the following statement to query Select * from system. help; (2) There are four files under $ ORACLE_HOME/sqlplus/admin/help: Helpbld. SQL,

Mysql does not allow remote connection by default, because it poses a great security risk. You need to manually add users who can remotely access the database. Method 1. log on to mysql locally, change the "host" item in the "user" table in the

Today, it is also a strange idea. MySQL verifies that varchar (15) will save 15 Chinese characters, and the first 15 will be automatically intercepted if the number exceeds 15. This concept may come from SQL server. In the varchar type, Chinese

Management notes for Oracle partition tables (only for common tables, that is, partition management for heap tables. IOT and cluster table are no longer discussed) 1. add partition)Syntax: alter table xxx add partition...It should be noted that if

I have known the MySQL command (command) Auto-completion function in the past few days (MySQL has been used for several years, but now I know it, I am so embarrassed) But it is not enabled by default. To enable this function, you can Vi/etc/my. cnf [