java - Java-Spring Boot-Mysql/Java-从一个表的列中获取车辆类型，并从另一个表中获取其总计数(QUANTITY)

这是我要执行的方案：
有两个表：带列的车辆表：vehicleType，brand。以及带有以下列的装运表：desc，vehicleType，date_delivered，date_dispatched。

我想从车辆表中获取所有的vehicleType，并获取他们在货运表中完成的货运总数。但是问题是，我不知道该怎么做。


  Shipment.java

    package com.pahrsek.smartfleet.model;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EnumType;
import javax.persistence.Enumerated;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;

import com.fasterxml.jackson.annotation.JsonIgnore;


/**
 * Delivery of goods
 * @author JRDomingo
 *
 */
@Entity
@Table(name="shipment")
public class Shipment {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    public Long id;

    @Column(name="booking_number",unique=true)
    public String bookingNumber;

    @Column(name="wb_number")
    public String wbNumber;

    @ManyToOne
    @JoinColumn(name="vehicle_id", referencedColumnName="id")
    public Vehicle vehicle;

    @ManyToOne
    @JoinColumn(name="customer_id", referencedColumnName="id")
    public Customer customer;

    public String origin;

    public String depot;

    @ManyToOne
    @JoinColumn(name="vendor_id", referencedColumnName="id")
    public Vendor vendor;

    public String type;

    @Column(name="commodity_type")
    public String commodityType;

    @Column(name="truck_type")
    public String truckType;

    @Enumerated(EnumType.STRING)
    public Status status;

    @Column(name="delivery_date")
    public Date deliveryDate;

    @Column(name="fuel_po")
    public String fuelPo;

    @Column(name="client_ref_no")
    public String clientReferenceNumber;

    public String remarks;

    @ManyToOne
    @JoinColumn(name="driver_id",referencedColumnName="id")
    public Personnel driver;

    @ManyToOne
    @JoinColumn(name="helper1_id",referencedColumnName="id")
    public Personnel helper1;

    @ManyToOne
    @JoinColumn(name="helper2_id",referencedColumnName="id")
    public Personnel helper2;


    public enum Status{
        New, Dispatched, Delivered, Completed, Cancelled
    }

    /******
     * ACTUAL DATES IMPLEMENTED
     ******/
    @Column(name="date_created")
    public Date dateCreated;

    @Column(name="date_dispatched")
    public Date dateDispatched;

    @Column(name="date_completed")
    public Date dateCompleted;

    @Column(name="date_cancelled")
    public Date dateCancelled;

    @Column(name="date_received")
    public Date dateReceived;

    @Column(name="farthest_destination")
    public String farthestDestination;

    @Column(name="client_rate")
    public Double clientRate;

    @Column(name="is_sub_con")
    public boolean isSubCon;

    @Column(name="sub_con_rate")
    public Double subConRate;

    @Column(name="fuel")
    public Double fuel;

    @Column(name="fuel_amount")
    public Double fuelAmount;

    @Column(name="route_code")
    public String routeCode;

    @ManyToOne
    @JsonIgnore
    @JoinColumn(name="dispatched_odometer_id",referencedColumnName="id")
    public RegularOdometerUsage dispatchedOdometer;

    @ManyToOne
    @JsonIgnore
    @JoinColumn(name="delivered_odometer_id",referencedColumnName="id")
    public RegularOdometerUsage deliveredOdometer;

    @ManyToOne
    @JsonIgnore
    @JoinColumn(name="completed_odometer_id",referencedColumnName="id")
    public RegularOdometerUsage completedOdometer;


    /**
     * index 0 = Driver , index 1 = Helper1, index 2 = Helper2
     */
    @JsonIgnore
    @OneToMany(mappedBy="shipment",targetEntity=PersonnelRate.class)
    public List<PersonnelRate> personnelRates = new ArrayList<PersonnelRate>();

    @JsonIgnore
    @ManyToOne
    @JoinColumn(name="company_id", referencedColumnName="id")
    public Company company;


    @JsonIgnore
    @ManyToOne
    @JoinColumn(name="prepared_user_id", referencedColumnName="id")
    public User preparedBy;


    @JsonIgnore
    @ManyToOne
    @JoinColumn(name="customer_invoice", referencedColumnName="id")
    public CustomerInvoice customerInvoice;

    @JsonIgnore
    @ManyToOne
    @JoinColumn(name="trucker_settlement", referencedColumnName="id")
    public TruckerSettlement truckerSettlement;

}

最佳答案

将COUNT（）与GROUP BY结合使用可按vehicleType将它们分组在一起

SELECT
 vehicle.vehicleType,
 count(shipment.id) as totalShipment
FROM
 Vehicle as vehicle
INNER JOIN Shipment as shipment ON shipment.vehicleType = vehicle.vehicleType group by vehicle.vehicleType