mongodb relational database

-related, database recovery and other DBA-related operations, and nosql Big data is more out of this range, streamline induction.There is a database of master-slave replication, read and write separation, data segmentation, clustering and so on are not on this basis, there is a chance to start another MySQL architecture optimization chapter.There are still some said, such as read-write separation with the m

Relational Database Standardization Theory functional dependency and paradigm theory the relational model can be formally represented as R (U, D, dom, F); U: Attribute Set, D: indicates the attribute domain, dom: ing set of attributes like domains. F: indicates the dependency set of data between attributes. 1. function dependencies are defined as follows: assume

database--the method of transforming from ER diagram to relational mapping Specific steps: 1.For each strong entity type E. Create a new table. Include as its columns, all the simple attributes and easy components of the composite attributes of E. Identify the PRI Mary Key and the alternate keys. Do not include any multi-valued attribute as a key. If The unique field of an entity is a multi-valued attribut

relationship that participates in the Union must have the same number of attributes, and the attribute type must be the same for the merge bit.b) Set difference operation Set-differenceThe sign bit of the set difference operation minus-,r-s results in tuples that exist in R but do not exist in S. The set difference operation requires the same set as the Union.c) Cartesian product Cartesian productThe x,instructorxteaches of the Cartesian product is the result of all possible combinations betwee

Label:sqlite-Open source, cross-platform, compact relational database-1 Learn SQLite database in 1 hours 1. Introduction SQLite is an open-source, embedded relational database that implements a self-contained, 0 configuration, transactional SQL

input database, because the lack of the product ID of the primary key, which is an insert exception.If the goods purchased from the current supplier are no longer needed, to be removed, but this supplier has other goods will be provided, but this time has not entered the data, if the deletion of existing products, will delete the supplier information, this is the deletion exception.The correct solution is to separate the supplier ID and the vendor ad

Label:Outline: A single data structure: RelationshipsTwo, relational operation: relational algebra language; relational calculus language; SQLIII. integrity constraints: Entities, references, user customizationsI. Integrity constraints1. Entity integrity: The individual components of the main attribute cannot be null values2. Referential integrity: The outer code

[PURPOSE] In the Microsoft SQL server environment of the given relational database management system, lab students can: 1, ms SQL Server understanding and environment familiar, understand the T-SQL of standard SQL expansion. 2. Master the data definition in the T-SQL environment, including database, basic table, view, index definition. 3, master the T-SQL enviro

is a right-to-left pop-up field, Lpop is a left-to-right pop-up field, Llen is a list of the lengths of the specified key Hash data type:127.0.0.1:6379[15]> Hmset member name Tom Age gender maleok# primary key and sub-key 127.0.0.1:6379[15]> hgetall member1) " Name "2)" Tom "3)" age "4)" 5 "[Gender] 6)" Male "#显示所有键值127 .0.0.1:6379[15]> hkeys member1)" name "2)" age "3)" Gender "# Show only sub-keys 127.0.0.1:6379[15]> hvals member1) "Tom" 2) "3" "Male" #显示子键值127 .0.0.1:6379[15]> Hstrlen member

be changed so that the transaction will still satisfy a+b=10, otherwise the transaction fails.3, I (isolation) IndependenceThe so-called independence refers to the concurrent transactions do not affect each other, if one transaction to access the data is being modified by another transaction, as long as another transaction is not committed, the data it accesses is not affected by uncommitted transactions.For example, there is a transaction from a to 100 yuan to the B account, in the case of the

DBMS (Database Management System) data management systemsRDBMS (relational database Management system) relational databases management systems The organizational structure of the data: Hierarchical typeMesh typeRelational (two-dimensional relational table) Note: A ta

, attribution College===> department can rely on the school number, can also rely on the school of attribution. You can split the two tables into one. (School number, name, gender) (department, School of Attribution)Some basic requirements of relational database in relational schema designData redundancy in---> database