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1 , MySQL principles of replication and processes. (1) First ask the basic principle flow, 3 threads and the association between them.A: MySQL replicates three threads: the main library thread, from the library I/O thread, from the library SQL

In the same table, the data is archived by placing the row in the inactive state. Database, you can compress optimizations for those inactive row. While archiving is implemented, applications can be restricted from accessing only those data in the

For the use of case, the simple case function is a simple case expression that uses an expression to determine the return value.Grammar:Case Search_expressionWhen Expression1 then RESULT1When Expression2 then RESULT2...When Expressionn then

1, the use of dual tableDual is a physically existing table in Oracle that can be read by any user, often in a SELECT statement block without a target table--View current connected userConnected to Oracle Database 10g Enterprise Edition Release 10.1.

In previous versions, the parent table could not be truncate directly when there was a foreign key constraint. In 12C, a cascade operation attribute was added to the truncate operation.If you create a FOREIGN key constraint, use "on Delete

Whether you are a "development engineer" or "implementation engineer", there may be many online design report requirements in the company's related systems. Before you design a report, first, we need to understand how to write SQL statements,

Oracle multi-key partition Test Partitions can be partitioned by two fields. The first column is compared first. If yes, the second column is ignored. If the first column is not met, the second column needs to be compared. This partitioning method

We all know the usage of Casewhen. Once a certain WHEN is satisfied, the data will exit the CASEWHEN instead of considering other cases, this article introduces the usage of casewhen in detail and gives an example. We all know the usage of Case when.

Common SQL commands @ oracle Data Type summary @ permission, role, User Creation and use @ pseudo column and precautions 1. user system permissions with different permissions: User name: sys/system (the default user name is sys, system); Password:

In this Document Symptoms Cause Solution Applies To:Oracle Application Object library-version 11.5.9 to 12.1.3 [Release 11.5 to 12.1]Oracle

Case when usage, simple Case FunctionUse a simple CASE expression to determine the return value. Syntax: CASE search_expression WHEN expression1 THEN result1 WHEN expression2 THEN result2 ... WHEN expressionN THEN resultN ELSE default_result Search

Here we have added a list of oracle functions that are helpful to ORACLE beginners. If you need them, you can check them out. Single-record functions in SQL1. ASCIIReturns the decimal number corresponding to the specified character;SQL> select ascii

When the online log is damaged (the database is shut down abnormally), you must immediately perform a full backup after Incomplete recovery. You cannot perform two Incomplete recovery operations consecutively. When the online log is damaged (the

When the online log is damaged (the database is shut down normally), create a table T2 to insert two rows of data. If the first row of data is written to the archived log, the second row of data is stored in the online log. When the online log is

[Q] How to restrict specific IP addresses to access the database[A] You can use the logon trigger, cmgw, or add A protocol under $ OREACLE_HOME/network/admin. ora file (Some OS may be. protocol. ora), 9i can directly modify sqlnet. ora: Add the

  A lock is a mechanism used by a database to control concurrent access to shared resources. The lock is used to protect the data being modified. Other users can update the data only after the transaction is committed or rolled back. Advantages of

Oracle DatabaseOfAutonomous transactionsThis is what we will introduce in this article. Next let's take a look at its mysteries. A database transaction is a unit operation. Either all operations are successful or all operations fail. In Oracle, a

Oracle 10g tablespace physical location transfer so I moved the tablespace to another hard disk, the process is as follows: Operating Environment: Database: Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 tablespace: database Files used

Oracle's default xml db sets the default http port to 8080, which is a very common port. Many other webservers use this port, so we need to modify it. Three methods:1. Dbca, select your database, and then select standard database features->

It's cool to listen to music, write a blog, and get it on a blog! This explains the functions of cube and rollup in SQL statements (used with group ); Question: Explanation of the answer:... let's look at the example. It's hard to describe