Database Administrator

Stored Procedures in Oracle: /* Create a storage function and return the name, salary, and annual income of the specified employee. */ Create or replace function queryEmp2 (eno in number, empname out VARCHAR2, empsal out NUMBER) -- Returns the

Oracle 11g (11.2.0.1.0) has a bug. When the table has no data, no segment is assigned. Solution: 1. insert a row and then roll back to generate a segment. This method inserts data into an empty table and then deletes it, resulting in a segment. An

1. First install the following necessary rpm packages with the root user # Rpm-Uvh libaio-0.3.106-3.2.x86_64.rpm# Rpm-Uvh libaio-devel-0.3.106-3.2.x86_64.rpm 2. Supporting asynchronous I/O at the system levelUnlike setting asynchronous IO in RHEL3

Cursor Concept A cursor is a memory Workspace of SQL, which is defined by the system or user as a variable. A cursor is used to temporarily store data blocks extracted from the database. Why use a cursor? The data in the database is stored in the

Introduction: Recently, I often see some posts about Oracle GG implementation cases in forums. It is true that GG does not have a lot of comprehensive information in various forums, especially the real implementation cases are even more rare. In

Summary: 1. Are the data stored in the database (data files) consistent? When the database is shut down, it should be consistent; when the database is shut down abnormally, it should be inconsistent; when the database is enabled, it may Inconsistent

If a Cache clause is specified when a table is created or modified, the table will be added to the database Cache for a long time when the data in the table is accessed for the first time, in this way, the user can access the table again, and can

I have studied several free database software to reduce the license fee. Here are some personal tokens for reference only. The first research is the well-known DB2, a database software that I have never been familiar with in my mind. It is said

Adjust the Byte of the CHAR/VARCHAR2 field of the table to CHAR Use the following SQL script: SetServeroutputOn DECLARE Sqlstr varchar2 (4000 ); CursorSqlcursIs SelectOwner, table_name, column_name, data_type,

#/Etc/init. d/mysqld startStart MySQLIf you use this command for the first time, your/var/lib/mysql database will be created. # Mysql-u rootYou do not need to enter a password for the first time.It is better to add a password to prevent intrusion.

ORA-01779 errors may occur when you try to update a subquery in Oracle. The error message is as follows: ORA-01779: cannot modify a column which maps to a non-key-preserved table for example, this error occurs when you use the following update

Two features of Oracle role 1) role DelayDelayed How to enable the role to take effect immediately:Set role name;For example:Set role resource;Delay recoveryThe following experiment demonstrates the delay recovery:Session (1) scott:Sys @ ORCL> conn

I.Library Cache Lock     Library cacheHandle stores the lock and pin information. In addition, both the Library cache handle and child cursor have lock and pin. These are called library cache lock and library cache pin. Library cachelock/pin is

After the system executes expdp export, alert. log reports the service name modification information, as follows: Wed Sep 05 02:09:29 2012Alter system set service_names = 'sys $ SYS. KUPC $ C_1_20120905020929.ZZBRAC3 'SCOPE = memory sid = 'zzbrac31 '

Using MySQL dual master + keepalived is a very good solution. In the MySQL-HA environment, MySQL is mutually master-slave, which ensures data consistency between the two MySQL databases, then, use keepalived to implement virtual IP addresses, and

Today, when the company changed tomcat, the connection to the database failed. In the beginning, the password expired. Later, the password was changed from Oracle. When trying to connect, an error was reported that the password was locked, check the

Srvctl is a command line tool provided by Oracle to manage the RAC environment of Oracle. Srvctl is introduced in Oracle 9i. Oracle10g and 11g greatly improve its functions. The following describes the simple usage of this command. 1. view the

Rollup is an extension of group by, which performs subtotal and total operations. cube contains rollup, which is a more granular subtotal and total. When there is only one field, rollup and cube are the same. You can use grouping to test rollup and

Cause: The union all operation is required in the query, and the operation cannot be completed because the LONG type field exists in the table. Modify the LONG type field to the CLOB type according to the specific business scenario. After the

Because the original ASM shared disk capacity is small, archive logs and backup files cannot be installed. Therefore, we decided to add a disk. 1. Add a virtual disk to node 1 and place it in the original shared directory named ASM4. Select SCSI and