不多說直接上代碼！

接口：

public interface CommodityMapper {
    int deleteByPrimaryKey(Integer productId);

    int insert(Commodity record);

    Commodity selectByPrimaryKey(Integer productId);

    List<Commodity> selectAll();

    List<Commodity> getType(int id);

    int updateByPrimaryKey(Commodity record);

    int getCount();

    List<Commodity> SearchCommodity(@Param("productName") String productName);//註意傳參的名字必須要和Mapper文件一致
 


}

Constroller層：

 //搜索
    @RequestMapping(path = "/search", method = RequestMethod.GET)
    public ResponseEntity Search(String productName) {
        if (commodityService.SearchCommodity(productName).size() != 0) {
            return ResponseEntity.ok(commodityService.SearchCommodity(productName));
        } 
 
else {
            return ResponseEntity.ok("error");
        }

    }

Mapper文件

    <select id="SearchCommodity"  resultType="string" resultMap="BaseResultMap">
select
c.product_id,
c.product_name,
c.product_content,
s.product_specs,
s.product_price,
d.product_simg
from commodity  c
cross join Standard  s
on c.product_id=s.product_id
cross join dommodityAttribute d
on  c.product_id=d.product_id
where c.product_name like concat(‘%‘,#{productName},‘%‘)  group by c.product_id
    
 
</select>

Mybatis,模糊查詢語句，以及傳參數的正確寫法