rollback

Finally decided to get the mail system again. Because the server often problems, DNS error, SMTP also often problems. Most importantly, because there were only two servers previously, this server acted on several roles (Pdc,isaserver,exchange

oracle| Script | data | database Oracle database replication Common scripts (Shi July 30, 2001 17:30) Oracle data replication is a relatively mature technology in Oracle database products and is an important part of the entire distributed computing

First, understand under what circumstances Oracle will produce ORA-01555 errors: Suppose there is a table1 table with 60 million rows of data, assuming that the full table Scan 1 times takes 2 hours, from the process: 1. At 1 o'clock, User a

I. BACKGROUND In the MySQL mysql.user table has saved the login user's permission information, the host and the user field is regarding the landing IP limit. But without such a table in SQL Server, what is the way SQL Server can achieve similar

This example describes the use of mysqldb under Python. Share to everyone for your reference. The specific analysis is as follows: Download Installation MySQLdb ①linux version http://sourceforge.net/projects/mysql-python/download, the

Blocking definition Blocking occurs when the first connection from the application controls the lock and the second connection requires a conflicting lock type. The result is to force the second connection to wait while blocking on the first

oracle| Data | database The use of a 1.having clause has a clause that controls the group of rows determined by the GROUP BY clause, allowing only constants, clustered functions, or columns in the GROUP BY clause to be involved in the HAVING clause

Program | control | data | Database in programming, often need to use transactions. A business is a series of operations that must be successful, and all other steps must be undone as long as one operation fails. For example, using ASP to develop a

mysql| Reference | Reference manual | Chinese MySQL 4.1.0 chinese reference manual---dog (heart sail) Translate MySQL Reference Manual for version 4.1.0-alpha. 6.7 MySQL Transaction and locking command 6.7.1 begin/commit/rollback syntax By

The printed font is static, and the page font is sleek and malleable. Designers must anticipate the end result of Cross-browser and end-user, not just learn how to achieve a particular visual appearance. In addition to mastering the simple rules,

MyISAM: This is the default type, which is based on the traditional ISAM type, and ISAM is the abbreviation for indexed sequential access method (indexed sequential access methods), which is the standard way to store records and files. Compared to

Strategy a property of a transaction Transactions have ACID properties: Atomic atomicity, consistent consistency, isolated isolation, durable permanent Atomicity is that a transaction should be a unit of work, the transaction completes, all work is

Data Buffer Hit ratio# The hit rate of the data block in the data buffer, usually should be above 90%, otherwise consider increase db_block_buffers (9i above but db_cache_size) Buffer nowait ratio# The wait rate in the buffer to get buffer

oracle| Recovery | data | database | Optimization The steps to minimize Oracle downtime are discussed here. All forms of downtime-planned or unplanned-always occur, and a DBA should have the right backup strategy so that it can recover more quickly

Oracle Trace Files Oracle trace files are grouped into three categories: One is the background alarm log file that records the activity of the background process during startup, shutdown, and running of the database, such as table space creation,

Class one or four isolation level The SQL standard defines 4 classes of isolation, including specific rules that define which changes are visible inside and outside the transaction and which are not. The low-level isolation level generally supports

Join order in the 1.WHERE clause: Oracle parses the WHERE clause in a bottom-up order, according to which the connection between the tables must be written before the other where conditions, and the conditions that can filter out the maximum number

18.3.1 use tdatabase part to join SQL Server 18.3.1.1 tdatabase Parts Overview Tdatabase the connection of a part-processing application to a single database. If you do not need to control the database join, you do not have to create the tdatabase

What is the relationship between Note 1, instance, and Sid? What is the relationship between an instance and a database? People often ask what is SID? Sid is a recurring variable in Oracle systems, such as environment variable ORACLE_SID,

Ado|command| Notes | objects First, the characteristics of the introduction ⒈sqlcommand: Represents a Transact-SQL statement or stored procedure to be executed on a SQL Server database. ⒉sqldatareader: Provides a way to read a forward-only row