emarketing concepts

In front, this article is part of the content from the Community official website after a moderate translation, part of the experience summary, part of the Plagiarism Network blog, (do not enumerate the references, in this apology) together, the purpose of this article, hope to summarize some useful, should pay attention to the things, the basic idea is to put forward a topic, in this topic , the related things added in, rather than separate chapters separately introduced, although the reason is

Note: This article only records chapter concepts and is used to recall knowledge systems. Reference book "Probability Theory and Mathematical Statistics Fourth Edition".Chapter One basic concept of probability theory random test (with three characteristics) sample space, random event sample space sample point random Event (event) event occurrence basic event inevitable event impossibility event (∅) event relationship with the event of the Operation Eq

CORBA Concepts (GIOP, IIOP, IOR, ORB, IDL) CorbaThe common Object request broker (Scheduler) program architecture (Common object Request broker Architecture), abbreviated to CORBA, is an object management organization (objects Management Group) in response to the demands of today's fast-growing hardware and software collaboration capabilities. In short, CORBA allows applications to communicate with other applications, regardless of where or by whom t

many other frameworks;Tool Library is more, such as: JSON library, XML library, date library, picture library, etc.; A framework may contain multiple (0 ~ n) Design patterns.In general development, there are many kinds of common frame patterns, such as MVC/MVVM/MVP/MTV/CBD and so on.MVC is a framework pattern rather than a design pattern, and generally MVC can be seen as a combination of 3 design patterns: The Observer pattern, the strategy pattern, and the combined pattern.--Frame is a great w

Tags: concept tag specific host NAT multiple effects add nbspIn the VLAN port mode of the switch: access,trunk！！！ The PC does not recognize the frame with tag, so all the tags sent to the host frame will be stripped.1. Access modeThe frame of all VLANs can be sent at this port, and the tag on the frame will be stripped off, which becomes an untagged frame sent to the link;On this port, the untagged frame on the link is hit on a specific tag on this port and then received;That is, the frames on t

Tags: href update mode tar ... Relational blank serial Fetch dataMySQL InnoDB engineShared Lock (S) Select ... lock in share mode, with shared lock data, other places can only be shared lock, cannot add exclusive lock.Exclusive Lock (X) Select ... for update, Update,delete,insert automatically adds exclusive locks to the data involved, with exclusive lock data, and no more locks anywhere else.Transaction four isolation Levels1. Non-committed read: can read uncommitted data.2. Submit read: Only t

a stable RAC version determines the stability of the RAC operation. It is important for database engineers and hardware engineers to have extensive environmental checks, validations, and extensive testing after deployment before installing the configuration.　　Second, high-performanceHigh performance is also a major headache for migrating from a single machine environment to a RAC environment, and RAC is not a high-performance solution. In the current hardware environment of gigabit Network, man

queryFrom sub-query: The query results of the inner layer as a temporary table for the outer SQL query againExists sub-query: The outer query results to the inner layer, see if the inner layer of the query is set up4. Union (Union) queryCombines the results of two queries and multiple queries, so the two queries display the same number of columns, preferably with the same data type.Views ViewA view is a virtual table formed by the results of a query. It is a table-based query result. Therefore,

/83/A2/wKioL1d5GqfyEG5EAAAuO7f5hiE118.png "border=" 0 "Style=" FONT-SIZE:13PX; line-height:1.5, "Name=" "" 267 "height=" 229 ">7 MySQL read-write separation implementation MYSQL-PROXYAMOEBA8 data splitting cobar9 mysql log binary log bin LPG storage location: Data directory under MYSQL-BIN.XXXXXXXXScroll: 1 to reach maximum on line; 2 Flush logs;3 Server restartClear Binary Log command: Purgeformat: statement, statement-based, not recommended Row, line based, recommended for use Mixed, mixed m

Database 1, consider the actual object of modeling Each real-world object that you want to model needs to have its own table. 2. Avoid saving redundant data To avoid update irregularities in 3 situations: modify, insert, and delete irregularities. 3. Use atomic column values Only one data is stored for each property of each row. Books ordered inconsistent When there are many-to-many relationships for two objects, such as the relationship between orders and books, you need to create one of the

, but each animal sleep situation is not the same, birds sleep in the tree, fish sleep under water, you can not specify the specific implementation details, so it is possible to define an abstract sleep method void sleep (); The specific animal implements the interface Override this abstract method to show the implementation details.Summarize inheritance and implementation: inherit generic, implement special. In the persistence layer constructed in this article, all of our entities easily have a

facilitate the search A hash file is stored, a field of data is hashed (hash operations, such as a fetch), and then stored in different buckets according to different results. The pointer is stored, and each row of data is stored with a pointer to the next line so that it does not have to be stored sequentially Tablespace: Storing data from multiple tables in the same table space, which is equivalent to a more advanced data storage spaceData dictionary: Metadata for relationships s

On a talk about MongoDB installation and management, which involves a number of concepts, data structure and some API calls, do not know it's okay, actually very simple, this will be a brief introduction.1. DocumentationThe document is the core concept of MongoDB, and multiple key-value pairs are placed together as a document, and the document is the most basic data structure for MONGODB to store data. MongoDB is in the form of documentation, using a

set a, the entity set B has at most an entity B associated with it, and vice versa. Recorded as 1:1. One -to-many connections (1:N): for each entity a in entity set a, there are n entities associated with entity set B, and for each entity B in entity set B, there is at most one entity in entity set a associated with it, which is said to have 1-to-many connections to entity set A and entity set B. Remember as 1:n. Many-to-many connections (M:N): If there are N entities in entity set B as

tablespace with a custom user. Because Oracle's database is not a common concept, Oracle has users and table spaces to manage and store data. But the table is not a table space to query, but by the user to check. Because different users can create a table of the same name in the same table space! Here the distinction is user! It is necessary to understand that the physical structure of a database is determined by the operating system files of the database, and that each Oracle database consist

, or revoked. The trigger type is divided into two types (according to the interval size of the triggered action): Row-level triggers (for each row): Trigger actions perform the corresponding times based on the number of rows in a table Statement-level trigger (for each STATEMENT): The trigger action occurs only once, regardless of how many rows the table has When you create a trigger, you must also specify a trigger action: INSERT, UPDATE, delete operation, specify at least one, or spec

. If you no longer need a table, you can delete it with the drop TABLE command. Like this: DROP TABLE my_first_table; DROP TABLE Products; Attempting to delete a nonexistent table is an error. However, in the SQL script file, we usually delete it unconditionally before creating the table and ignore the error message, so the script succeeds regardless of the table memory being deleted. Of course you can also use the DROP TABLE IF EXISTS to avoid error messages, but this does not conform to the SQ

Select,update,delete,insert on borrow to Admin_role; Grant Select,update,delete,insert on student to Admin_role; 3, give roles to users. Student_role Grant Student_user,admin_role Grant Admin_user. ①student_role Grant Sthdent_user [sql] exec sp_addrolemember @rolename = ' student_role ', @membername = ' student_user '; ②admin_role Grant Admin_user [sql] exec sp_a Ddrolemember @rolename = ' admin_role ', @membername = ' admin_user '; Stu Five, respectively

Tags: type insert current not latest UPD creation time date defaultThe old concept of the Internet1th: The minimum value for the datetime of the previous MySQL is: ' 1000-01-01 00:00:00 ' (seemingly), but the latest MySQL test datetime minimum value can be: ' 0000-00-00 00:00:00 ' (0000-00-01 00:00:00 can also be inserted),But I'm using ' 0001-01-01 00:00:00 ' as the minimum value (typically used instead of a null value as the default value for that column) because the datetime minimum value for

. Based on things(1). ConceptA transaction-level temporary table is a transaction-related, when a transaction is committed or the transaction is rolled back, the data in the temporary table is truncated itself, and the other content and session-level temporary tables are consistent (including when exiting the session, the transaction-level temporary table will be automatically truncated).(2). syntaxCREATE GLOBAL Temporary TABLE xxgl.xxgl_test_journal (JE_ID number,Je_name VARCHAR (BYTE)) on comm