Tag：Field name
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Time：2021-1-23
Alibaba: MySQL database specification Introduction: it is based on the expansion of Alibaba database design specification design code 1. [recommend] field allows appropriate redundancy to improve query performance, but data consistency must be considered. Redundant fields should follow the following rules: Is not a frequently modified field. It is not a varchar super long […]
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Time：2021-1-15
If you want to see the conclusion directly, you can jump toFast generation method In tob projects, it is inevitable to process tree related data, such as multi-level Department list, multi-level distribution list, and so on. For all cascading data with upper and lower levels, it is inevitable to generate tree structure data. There are […]
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Time：2021-1-14
Core overview: in the development, we use SQL commands to operate the database and the data in the database. The common operations include the addition, deletion, modification and query of the database and tables. In this article, we will first learn how to use SQL statements to realize the basic operations of the database and […]
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Time：2021-1-14
Apache Flink provides two top-level relational APIs, namely table API and SQL. Flink realizes batch flow unification through table API & SQL. The table API is a language integrated query API for Scala and Java, which allows queries of relational operators (such as select, where and join) to be combined in a very intuitive way. […]
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Time：2020-12-31
Data table operation of MySQL Data table operation Each data table is equivalent to a file, which is divided into table structure and table record. Table structure: including storage engine, field, main foreign key type, constraint condition, character encoding, etc Table record: each row of data in a data table (excluding field rows) id name […]
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Time：2020-12-24
–Create database database namecreate database Unit2_1712A –Use database [open database]–Use database nameuse Unit2_1712A –Delete database–Drop database namedrop database Unit2_1712A –Backup database–Backup database name to disk =’path of file storage ‘backup database Unit2_1712A to disk=’F:\\beifen\bk.bak’ –Restore database–Restore database database database name from disk =’File storage path ‘restore database Unit2_1712A from disk=’F:\\beifen\bk.bak’ […]
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Time：2020-12-19
SQL Database structure operation SQL 1. View all databases show databases; 2. Switch to database Use database name; 3. Create database Create database database name; Create database database name charset ‘utf8’; 4. Delete database Drop database database name; Table structure operation SQL 1. View all tables in a database show tables; 2. View table structure […]
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Time：2020-12-4
Using a custom ID generator realizationIdentifierGeneratorInterface @Component public class CustomerIdGenerator implements IdentifierGenerator { @Override public Number nextId(Object entity) { //Fill in your own ID generator, return HolaSms.snowFlake(); } } The ID filling method is specified in the entity class or configuration file configuration file mybatis-plus: global-config: db-config: id-type: assign_id Entity class @TableId(type = IdType.ASSIGN_ID) private […]
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Time：2020-12-3
1、 Background E. F. Codd first put forward the relational model of database system in 1970. From then on, he initiated the research of relational database method and relational data theory, which laid a theoretical foundation for database technology, and database technology began to flourish. With the commercial database management systems released by several major […]
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Time：2020-11-29
Property table_ Props) has the following structure Data volume above 800W Field name type explain id int id pn_id int Property type pv_id int Property value product_id int Product ID Among them, product_ ID and PN_ id,pv_ ID is a one to many relationship.The data is similar to this: product_id pn_id pv_id 10970 5 (model) […]
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Time：2020-11-27
Swaggos Swaggos is a golang version of swagger document generator, which provides native code wrapper and supports mainstream web framework wrapper install go get -u github.com/clearcodecn/swaggos Examples Currently, only gin wrapper is supported package main import ( “github.com/clearcodecn/swaggos” “github.com/clearcodecn/swaggos/ginwrapper” “github.com/gin-gonic/gin” “github.com/go-openapi/spec” ) type User struct { Username string `json:”username” required:”true”` Password string ` JSON: “password” […]
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Time：2020-11-16
preface The project of homework has finally come to an end. For the time being, I continue to write the log system this week. Unfortunately, I started to practice my class three this week. At first, I practiced driving all day, which reduced the time of writing code every day. Later, the time was adjusted […]
