Database Administrator

[Add Field Command]Alter table tab_nameADD col_name col_default ADD a fieldMysql> alter table Zone add tinyint not null;ADD col_name col_default AFTER col_name ADD the newly defined field to a fieldMysql> alter table Zone add tinyint not null after

1. Transaction concept: Concept: transactions in databases are logical units of work. A transaction is composed of one or more SQL statements that complete a group of related behaviors, the transaction mechanism is used to ensure that the operations

MySQL Replication is usually used for MySQL services for read/write splitting, HA, hot backup, or incremental operations, and the Master/Slave mechanism is indispensable. However, errors 1032 and 1052 are reported in many cases. First 1032. Error_

Actual Example: Create or replace procedure pro_droptable IS Cursor cur is Select table_name from user_tables where table_name like 'temptable % '; Drop_ SQL varchar2 (1000 ); Table_number number; BEGIN Select count (*) INTO table_number from

Due to objective reasons of disk space, it is not possible to use rman and expdp to generate landing files for recovery or import operations. Therefore, impdp is used to import data using network_link, this method is really good, and because impdp

I. Fault occurrence: This morningQQSend a friend to me and sayOracleSoftware Installation Error: Ii. Fault Analysis: The fault is caused by failure.OracleThe official documentationLinuxAs a result: Iii. UseRootUser Logon editing/Etc/security/limits.

The configuration of ASM in Oracle RAC can be implemented in two ways: raw and asmlib. Raw is recommended for actual maintenance. There are two ways to use raw: multipath and UDEV. On the RedHat platform, refer: Redhat 5.4 + ASM + RAW + Oracle 10g

MySQL, a database generated by the Internet, is used by countless websites and games. It is said that google, tencent, and taobao are all using it. During the rapid development of the Internet, because of the needs of high-speed cache and the

1. Prepare the system environment before installing Oracle 10 Gb database 1. view the system version, kernel version, number of operating system digits, memory and swap partition size, file system space, host name, IP address, and so on. [Root @ rac0

Oracle provides a sequence object that is provided by the system for auto-incrementing serial numbers. It is usually used to generate auto-incrementing primary keys or serial numbers for database data records. The following describes common

Query and use of the Oracle Tree Structure Use of the start with... connect by prior clause in OracleConnect by is used in structured queries. Its basic syntax is:Select... from tablename start with condition 1Connect by condition 2Where Condition 3;

The Like operators in Oracle use '_' and '%' As wildcards, just Like this: SELECT name FROM test_like WHERE name like'_ A %'; That is, all rows with the 2nd letters a in the name column of the test_like table are matched. However, note that Oracle

Install Mysql under Fedora 16 1. Download the MySQL Installation FileThe following two files are required to install MySQL:MySQL-client-5.1.55-1.glibc23.i386.rpm MySQL-server-5.1.55-1.glibc23.i386.rpm For:

1. view the default tablespace of the current user: SQL> select username, default_tablespace from user_users; 2. view the role of the current user: SQL> select * from user_role_privs; 3. view the current user's system permissions and table-level

After installing Oracle, you must add the following settings in linux to use oracle normally: Set two environment variables: ORACLE_HOME and ORACLE_SID, and add the bin directory of ORACLE to PATH. Generally, ORACLE_SID = orcl is installed by

The script for MySQL database flushing contains Chinese characters. After logging on with the MySQL command, it is flushed into the database and garbled during reading. The possible causes are as follows: After MySQL is installed, the client

Today, I found image errors stored in MongoDb GridFS. I checked the logs and found many logs similar to the following: Sat Mar 31 16:10:45 [conn42882] ns: fangdd. fs. chunks cocould not initialize cursor should SS all shards because: ns: mydb. fs.

MySQL innodb supports storing tables and indexes on bare devices. The storage I/O wait problem has always been the key to affecting database performance, bare devices do not need to be processed by the file system I/O. Therefore, the performance has

1. Problem DescriptionThe maintenance personnel reported to the center that the database/dev/fslv00 _ usage rate exceeded 88%. 2. Problem Analysis ProcessAfter investigation, a large number of *. aud files are generated under the minicomputer/Oracle/

Notice: written based on Ubuntu1. About MySQL Character Set MySQL Character Set Support has two aspects: Character set and Collation ). MySQL supports character sets in four layers: server, database, table, and connection ). MySQL can refine the