MySQL related terms

database
Organize... According to the data structure 、 Warehouse for storing and managing data ; Is a long-term storage in the computer 、 organized 、 Can share
Of 、 A collection of large amounts of data under unified management ;
OLTP
OLTP（on-line transaction processing） Online transaction processing ; Addition, deletion, modification and query of main databases ;
OLTP It is mainly used to record the occurrence of certain business events ; The data will be updated in the database by adding, deleting and modifying
operation , It requires high real-time performance 、 Strong stability 、 Make sure the data is updated in time ;
OLAP
OLAP（On-Line Analytical Processing） Online analytical processing ; Mainly for database query ;
When the data accumulates to a certain extent , We need to make a summary analysis of what happened in the past , You need to put the past period of time
Take out the data generated in for statistical analysis , Get the information we want from it , Support the company in making decisions , At this time
It's doing OLAP 了 ;
SQL
Definition
Structured query language (Structured Query Language) abbreviation SQL, Is a special purpose programming language , It's a number
Database query and programming language , For data access and query 、 Update and manage relational database system .SQL It's relational data
Standard language for library systems .
Relational databases include ：MySQL, SQL Server, Oracle, Sybase, postgreSQL as well as MS Access etc. ;
SQL The order includes ：DQL、DML、DDL、DCL as well as TCL;
DQL
Data Query Language - Data query language ;
select ： Retrieve specific records from one or more tables ;
DML
Data Manipulate Language - Data operation language ;
insert ： insert record ;
update ： Update record ;
delete ： Delete record ;
DDL
Data Define Languge - Data definition language ;
create ： Create a new table 、 View of the table 、 Or objects in the database ;
alter ： Modify existing database objects , For example, modify the attributes or fields of the table ;
drop ： Delete table 、 Database objects or views ;
DCL
Data Control Language - Data control language ;
grant ： Grant user rights ;
revoke ： Reclaim user rights ;
TCL
Transaction Control Language - Transaction control language ;
commit ： Transaction submission ;
rollback ： Transaction rollback ;
Database terminology
database ： A database is a collection of related tables ;
Data sheet ： A table is a matrix of data ;
Column ： A column contains the same type of data ;
That's ok ： Or record is a set of related data ;
Primary key ： The primary key is unique ; A data table can only contain one primary key ;
Foreign keys ： Foreign keys are used to associate two tables , To ensure referential integrity ;MyISAM The storage engine itself does not support foreign keys , Only play a note
Release effect ; and innodb Full support for foreign keys ;
Composite key ： Or key combination ; Use multiple columns as an index key ;
Indexes ： Data for quick access to data tables ; An index is a structure that sorts the values of one or more columns in a table ;
create table parent (
id int not null,
primary key(id)
) engine=innodb;
create table child (
id int,
parent_id int,
foreign key(parent_id) references parent(id) ON DELETE CASCADE ON UPDATE
CASCADE
) engine=innodb;
– The referenced table is the parent table , The referenced table is called a child table ;
– When defining a foreign key , You can set the behavior ON DELETE and ON UPDATE, The action when the behavior occurs can be selected ：
– CASCADE Sub tables do the same thing
– SET NULL The corresponding fields of the updated sub table are NULL
– NO ACTION The parent class makes the corresponding behavior report