MyBatis How to spell dynamic SQL in @Select annotations

 
@Mapper
public interface DemandCommentMapper extends BaseMapper<DemandComment>{
    @Select("SELECT "
            + "a.id as ‘id‘,a.create_date as ‘createDate‘,a.content as ‘content‘,"
            + "a.parent_id as ‘parentId‘,a.first_comment_id as ‘firstCommentId‘,"
            + "b.id as ‘fromUser.id‘,b.realname as ‘fromUser.realname‘,b.avatar as ‘fromUser.avatar‘,"
            + "c.id as ‘toUser.id‘,c.realname as ‘toUser.realname‘,c.avatar as ‘toUser.avatar‘ "
            + "FROM t_demand_comment a "
            + "LEFT JOIN t_user b ON b.id = a.from_uid "
            + "LEFT JOIN t_user c ON c.id = a.to_uid "
            + "WHERE a.demand_id = #{demandId} "
            + "ORDER BY a.create_date ASC"
            + "LIMIT #{startNo},#{pageSize}")
    public List<DemandComment> listDemandComment(@Param("demandId") Long demandId, 
                             @Param("startNo") Integer pageNo, 
                             @Param("pageSize") Integer pageSize);

So the whole sentence is written dead, if I want to according to PageNo and pagesize is empty to determine whether the need for paging, how to do?

If you use XML to configure it, you can use

 
 
<when test=‘startNo!=null and pageSize != null ‘>
  LIMIT #{startNo},#{pageSize}
</when>

What if this is done with @select?

Method: Surround with a script tag and write as XML syntax

 
@Mapper
public interface DemandCommentMapper extends BaseMapper<DemandComment>{
    @Select("<script>"
            + "SELECT "
            + "a.id as ‘id‘,a.create_date as ‘createDate‘,a.content as ‘content‘,"
            + "a.parent_id as ‘parentId‘,a.first_comment_id as ‘firstCommentId‘,"
            + "b.id as ‘fromUser.id‘,b.realname as ‘fromUser.realname‘,b.avatar as ‘fromUser.avatar‘,"
            + "c.id as ‘toUser.id‘,c.realname as ‘toUser.realname‘,c.avatar as ‘toUser.avatar‘ "
            + "FROM t_demand_comment a "
            + "LEFT JOIN t_user b ON b.id = a.from_uid "
            + "LEFT JOIN t_user c ON c.id = a.to_uid "
            + "WHERE a.demand_id = #{demandId} "
            + "ORDER BY a.create_date ASC "
            + "<if test=‘startNo!=null and pageSize != null ‘>"
            + "LIMIT #{startNo},#{pageSize}"
            + "</if>"
            + "</script>")
    public List<DemandComment> listDemandComment(@Param("demandId") Long demandId, 
                             @Param("startNo") Integer pageNo, 
                             @Param("pageSize") Integer pageSize);

Project examples

 
 @Select("<script>"
            +"select * from mi_taobao where 1=1"
            +"<if test=‘status != null‘>"
            +"and status = #{status}"
            +"</if>"
            +"</script>")
    public List<Taobao> getTaobao(@Param("status") Integer status);

There is also a problem here is error: caused By:org.apache.ibatis.reflection.ReflectionException:There is no getter for property named ' Status ' in ' Class Java.lang.Interger '

Cause: The problem here is that the parameters defined in the DAO method are inconsistent with the attributes defined in the entity.

Solution: The DAO layer plus @Param ("userId") annotations can be (add @Param ("status") in the instance)

Public list<dictitem> Selectkeybyuserid (@Param ("userid") long userId);

MyBatis How to spell dynamic SQL in @Select annotations