Tag:Main table

  • Database design of microservices


    I don’t expect life to go smoothly all the time, but I hope that when it comes to life, I can be its opponent. ​​​​ Separate database The key of microservice design is database design. The basic principle is that each service has its own database, and only the microservice itself can access the database. […]

  • Record a real production environment accident, 200000 records were lost, and the MySQL delete command stepped on the pit, not intentionally deleting the database


    –The main table before this launch, MD_ poc_ I didn’t put in other fields of survey, which has nothing to do with the bug I’m going to talk about this time. DROP TABLE IF EXISTS md_poc_survey; CREATE TABLE `md_poc_survey` ( `member_ survey_ id` int(10) NOT NULL AUTO_ Add comment ‘member questionnaire self increment ID’ PRIMARY […]

  • The function of (+) in SQL statement


    Demo example Note: in the following example, table a is an employee table with four employees, namely, a, B, C and D, all of whom are male M. Table B is the salary table. There are four employees a, B and D. the corresponding salary is 1000, 2000, 4000. Then we demonstrate the (+) and […]

  • Repeater nested loop


    Main table field name subset operation Main table field Sub table corresponding data 1 Sub table corresponding data 2 modify see No record ‘:’% > Front desk Code: //Main table data binding private void RptBind(string _strWhere, string _orderby) {this.rptList.DataSource =dt; this.rptList.DataBind(); } //Side table data binding protected void Getdata(object sender, RepeaterItemEventArgs e) { if (e.Item.ItemType […]

  • Oracle (PLSQL) Introduction 4


    Previous chapter: introduction to Oracle III Learning video: https://www.bilibili.com/video/BV1tJ411r7EC?p=35 Oracle table connection: internal connection and external connection. The external connection is divided into left connection and right connection. In multi table query, if there is no conditional association between tables, all matching results will be found. For example, table a has 6 pieces of data, […]

  • Oracle (PLSQL) introduction 5


    Learning video: https://www.bilibili.com/video/BV1tJ411r7EC?p=55 Data integrity: ensure that the data inserted into the table must be correct. Including entity integrity, region integrity, reference integrity and custom integrity. Constraints: constraints are used to ensure data integrity, including primary key constraints (PK), unique constraints (), check constraints, and foreign key constraints. The difference between a primary key and […]

  • Mysql database: application of data integrity and constraints


    Data integrity 1. Domain integrity: ——– match integrity: non empty, defaultFields / columns 2. Entity integrity: —— matching integrity: primary key, unique keyRecord / line 3. Referential integrity: —— matching integrity: foreign keyBetween tables Constraints: constraint Constraint classification in MySQL Primary key: primary keyUnique key: uniqueNot nullDefault: defaultForeign key The primary key, unique key, and […]