Important things

302 http response with Location header for url redirection(GET and Head) - 307 for temporary redirection ,==> Spring Sleuth - tracing in microservices, ==> https://astikanand.github.io/techblogs/high-level-system-design/design-bookmyshow, https://www.hellointerview.com/learn/system-design/in-a-hurry/introduction

Friday, 25 June 2021

Customer Order Database design

 You need four tables, something like this:

Possible Simplified Database Model

Customers

Contains a list of customers. One row per Customer. Would contain all the customers information - their contact details, etc...

Orders

Contains a list of orders. One row per order. Each order is placed by a customer and has a Customer_ID - which can be used to link back to the customer record. Might also store the delivery address, if different from the customers address from their record - or store addresses in separate tables.

OrderItems

Contains a list of order items. One row for each item on an order - so each Order can generate multiple rows in this table. Each item ordered is a product from your inventory, so each row has a product_id, which links to the products table.

Products

Contains a list of products. One row per product. Similar to the customers table, but for products - contains all the product details.

Here's the SQL code that you could use to create this structure - it will create a database for itself called mydb:

CREATE SCHEMA IF NOT EXISTS `mydb` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci ;
USE `mydb` ;

-- -----------------------------------------------------
-- Table `mydb`.`Customer`
-- -----------------------------------------------------
CREATE  TABLE IF NOT EXISTS `mydb`.`Customer` (
  `ID` INT NOT NULL ,
  `Name` TEXT NOT NULL ,
  `PhoneNo` VARCHAR(45) NULL ,
  PRIMARY KEY (`ID`) )
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `mydb`.`Order`
-- -----------------------------------------------------
CREATE  TABLE IF NOT EXISTS `mydb`.`Order` (
  `ID` INT NOT NULL ,
  `customer_id` INT NULL ,
  PRIMARY KEY (`ID`) ,
  INDEX `fk_Order_1_idx` (`customer_id` ASC) ,
  CONSTRAINT `fk_Order_1`
    FOREIGN KEY (`customer_id` )
    REFERENCES `mydb`.`Customer` (`ID` )
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `mydb`.`Product`
-- -----------------------------------------------------
CREATE  TABLE IF NOT EXISTS `mydb`.`Product` (
  `ID` INT NOT NULL ,
  `Name` VARCHAR(45) NOT NULL ,
  `Description` TEXT NULL ,
  PRIMARY KEY (`ID`) )
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `mydb`.`OrderItem`
-- -----------------------------------------------------
CREATE  TABLE IF NOT EXISTS `mydb`.`OrderItem` (
  `ID` INT NOT NULL ,
  `Order_ID` INT NOT NULL ,
  `Product_ID` INT NOT NULL ,
  `Quantity` INT NOT NULL ,
  PRIMARY KEY (`ID`) ,
  INDEX `fk_OrderItem_1_idx` (`Order_ID` ASC) ,
  INDEX `fk_OrderItem_2_idx` (`Product_ID` ASC) ,
  CONSTRAINT `fk_OrderItem_1`
    FOREIGN KEY (`Order_ID` )
    REFERENCES `mydb`.`Order` (`ID` )
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `fk_OrderItem_2`
    FOREIGN KEY (`Product_ID` )
    REFERENCES `mydb`.`Product` (`ID` )
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;

USE `mydb` ;

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