关于#java#的问题：private Map

mybatisplus中数据库中Date类型的字段为什么能和字符串类型的相比较

//作比较的相关代码
 @Override
    public void patientRemind() {

        QueryWrapper queryWrapper=new QueryWrapper<>();
        //在下面这段代码中，reserve_date字段和调用toString方法后的字符串类型相比较，
       // 能得到正确结果
        queryWrapper.eq("reserve_date",  new DateTime().toString("yyyy-MM-dd"));
        queryWrapper.ne("order_status",-1);
        List orderInfos = baseMapper.selectList(queryWrapper);
        for (OrderInfo orderInfo : orderInfos) {
            MsmVo msmVo = new MsmVo();
            msmVo.setPhone(orderInfo.getPatientPhone());
            String reserveDate = new DateTime(orderInfo.getReserveDate()).toString("yyyy-MM-dd") + (orderInfo.getReserveTime()==0 ? "上午": "下午");
            Map param = new HashMap(){{
                put("title", orderInfo.getHosname()+"|"+orderInfo.getDepname()+"|"+orderInfo.getTitle());
                put("reserveDate", reserveDate);
                put("name", orderInfo.getPatientName());
            }};
            msmVo.setParam(param);
            rabbitService.sendMessage(MqConst.EXCHANGE_DIRECT_MSM,MqConst.ROUTING_MSM_ITEM,msmVo);
        }
    }

//实体类相关代码

//orderInfo类
package com.atguigu.yygh.model.order;

import com.atguigu.yygh.model.base.BaseEntity;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableName;
import com.fasterxml.jackson.annotation.JsonFormat;
import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;

import java.math.BigDecimal;
import java.util.Date;

/**
 * 

 * Order
 * 

 *
 * @author qy
 */
@Data
@ApiModel(description = "Order")
@TableName("order_info")
public class OrderInfo extends BaseEntity {
    
    private static final long serialVersionUID = 1L;

    @ApiModelProperty(value = "userId")
    @TableField("user_id")
    private Long userId;

    @ApiModelProperty(value = "订单交易号")
    @TableField("out_trade_no")
    private String outTradeNo;

    @ApiModelProperty(value = "医院编号")
    @TableField("hoscode")
    private String hoscode;

    @ApiModelProperty(value = "医院名称")
    @TableField("hosname")
    private String hosname;

    @ApiModelProperty(value = "科室编号")
    @TableField("depcode")
    private String depcode;

    @ApiModelProperty(value = "科室名称")
    @TableField("depname")
    private String depname;

    @ApiModelProperty(value = "排班id")
    @TableField("hos_schedule_id")
    private String scheduleId;

    @ApiModelProperty(value = "医生职称")
    @TableField("title")
    private String title;

    @ApiModelProperty(value = "安排日期")
    @JsonFormat(pattern = "yyyy-MM-dd")
    @TableField("reserve_date")
    private Date reserveDate;

    @ApiModelProperty(value = "安排时间（0：上午 1：下午）")
    @TableField("reserve_time")
    private Integer reserveTime;

    @ApiModelProperty(value = "就诊人id")
    @TableField("patient_id")
    private Long patientId;

    @ApiModelProperty(value = "就诊人名称")
    @TableField("patient_name")
    private String patientName;

    @ApiModelProperty(value = "就诊人手机")
    @TableField("patient_phone")
    private String patientPhone;

    @ApiModelProperty(value = "预约记录唯一标识（医院预约记录主键）")
    @TableField("hos_record_id")
    private String hosRecordId;

    @ApiModelProperty(value = "预约号序")
    @TableField("number")
    private Integer number;

    @ApiModelProperty(value = "建议取号时间")
    @TableField("fetch_time")
    private String fetchTime;

    @ApiModelProperty(value = "取号地点")
    @TableField("fetch_address")
    private String fetchAddress;

    @ApiModelProperty(value = "医事服务费")
    @TableField("amount")
    private BigDecimal amount;

    @ApiModelProperty(value = "退号时间")
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm")
    @TableField("quit_time")
    private Date quitTime;

    @ApiModelProperty(value = "订单状态")
    @TableField("order_status")
    private Integer orderStatus;

}

//BaseEntity 类
package com.atguigu.yygh.model.base;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableLogic;
import com.fasterxml.jackson.annotation.JsonFormat;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;

import java.io.Serializable;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

@Data
public class BaseEntity implements Serializable {

    @ApiModelProperty(value = "id")
    @TableId(type = IdType.AUTO)
    private Long id;

    @ApiModelProperty(value = "创建时间")
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    @TableField("create_time")
    private Date createTime;

    @ApiModelProperty(value = "更新时间")
    @TableField("update_time")
    private Date updateTime;

    @ApiModelProperty(value = "逻辑删除(1:已删除，0:未删除)")
    @TableLogic
    @TableField("is_deleted")
    private Integer isDeleted;

    @ApiModelProperty(value = "其他参数")
    @TableField(exist = false)
    private Map param = new HashMap<>();
}

//数据库内容

img

不同数据库有不同的表现，mysql支持日期和字符串直接比较，但是oracle必须用to_date函数转换，比如

-- MySQL写法
SELECT * FROM t WHERE d > '2023-04-01';

-- Oracle写法
SELECT * FROM t WHERE d > to_date('2023-04-01', 'yyyy-mm-dd');

所以这是一个数据库支持与否的问题，并不是mybatis支持与否的问题

这个是sql 支持 date类型字段直接和 字符串比较，mybatis-plus 最终也是将sql条件拼成 类似 date = '2023-04-01' 这样

不知道你这个问题是否已经解决, 如果还没有解决的话:

如果你已经解决了该问题, 非常希望你能够分享一下解决方案, 写成博客, 将相关链接放在评论区, 以帮助更多的人 ^-^