1.根据同一数据库内同一列的不同值进行查询,相同值的其他数据(mapper文件 type是列的属性值)
select type,SUM(num) as num from ds_statistics
<trim prefix="where" prefixOverrides="and|or">
<if test="statistics.beginDate != null">
and created_at>=#{statistics.beginDate}
</if>
<if test="statistics.endDate != null">
<![CDATA[and created_at<=#{statistics.endDate}]]>
</if>
</trim>
group by type
2.实现数据的批量删除(mapper文件)
<delete id="batchDestory">
delete from ds_goods where id in(
<foreach collection="ids" item="id" index="index" separator=",">
#{id}
</foreach>
)
</delete>
3.实现数据的批量增加(mapper文件)
dao文件对应的方法:batchInsert(@Param("list") List<OrderDetail> list, @Param("orderId") Long orderId);
list对应的是下面的list,orderDetail对应的list的实体类
<insert id="batchInsert">
insert into ds_order_detail(goods_id, order_id, num, created_at, creator, updated_at, modifier) values
<foreach collection="list" item="orderDetail" index="index" separator=",">
(#{orderDetail.goods.id}, #{orderId}, #{orderDetail.num}, now(), #{orderDetail.creator}, now(),
#{orderDetail.modifier})
</foreach>
</insert>
4.mybatis中使用in查询时注意事项
1. 当查询的参数只有一个时
findByIds(List<Long> ids)
1.a 如果参数的类型是List, 则在使用时,collection属性要必须指定为 list
<select id="findByIdsMap" resultMap="BaseResultMap">
Select
<include refid="Base_Column_List" />
from jria where ID in
<foreach item="item" index="index" collection="list"
open="(" separator="," close=")">
#{item}
</foreach>
</select>
findByIds(Long[] ids)
1.b 如果参数的类型是Array,则在使用时,collection属性要必须指定为 array
<select id="findByIdsMap" resultMap="BaseResultMap">
select
<include refid="Base_Column_List" />
from jria where ID in
<foreach item="item" index="index" collection="array"
open="(" separator="," close=")">
#{item}
</foreach>
</select>
2. 当查询的参数有多个时,例如 findByIds(String name, Long[] ids)这种情况需要特别注意,在传参数时,一定要改用Map方式, 这样
在collection属性可以指定名称,下面是一个示例
Map<String, Object> params = new HashMap<String, Object>(2);
params.put("name", name);
params.put("ids", ids);
mapper.findByIdsMap(params);
<select id="findByIdsMap" resultMap="BaseResultMap">
select
<include refid="Base_Column_List" />
from jria where ID in
<foreach item="item" index="index" collection="ids"
open="(" separator="," close=")">
#{item}
</foreach>
</select>
select type,SUM(num) as num from ds_statistics
<trim prefix="where" prefixOverrides="and|or">
<if test="statistics.beginDate != null">
and created_at>=#{statistics.beginDate}
</if>
<if test="statistics.endDate != null">
<![CDATA[and created_at<=#{statistics.endDate}]]>
</if>
</trim>
group by type
2.实现数据的批量删除(mapper文件)
<delete id="batchDestory">
delete from ds_goods where id in(
<foreach collection="ids" item="id" index="index" separator=",">
#{id}
</foreach>
)
</delete>
3.实现数据的批量增加(mapper文件)
dao文件对应的方法:batchInsert(@Param("list") List<OrderDetail> list, @Param("orderId") Long orderId);
list对应的是下面的list,orderDetail对应的list的实体类
<insert id="batchInsert">
insert into ds_order_detail(goods_id, order_id, num, created_at, creator, updated_at, modifier) values
<foreach collection="list" item="orderDetail" index="index" separator=",">
(#{orderDetail.goods.id}, #{orderId}, #{orderDetail.num}, now(), #{orderDetail.creator}, now(),
#{orderDetail.modifier})
</foreach>
</insert>
4.mybatis中使用in查询时注意事项
1. 当查询的参数只有一个时
findByIds(List<Long> ids)
1.a 如果参数的类型是List, 则在使用时,collection属性要必须指定为 list
<select id="findByIdsMap" resultMap="BaseResultMap">
Select
<include refid="Base_Column_List" />
from jria where ID in
<foreach item="item" index="index" collection="list"
open="(" separator="," close=")">
#{item}
</foreach>
</select>
findByIds(Long[] ids)
1.b 如果参数的类型是Array,则在使用时,collection属性要必须指定为 array
<select id="findByIdsMap" resultMap="BaseResultMap">
select
<include refid="Base_Column_List" />
from jria where ID in
<foreach item="item" index="index" collection="array"
open="(" separator="," close=")">
#{item}
</foreach>
</select>
2. 当查询的参数有多个时,例如 findByIds(String name, Long[] ids)这种情况需要特别注意,在传参数时,一定要改用Map方式, 这样
在collection属性可以指定名称,下面是一个示例
Map<String, Object> params = new HashMap<String, Object>(2);
params.put("name", name);
params.put("ids", ids);
mapper.findByIdsMap(params);
<select id="findByIdsMap" resultMap="BaseResultMap">
select
<include refid="Base_Column_List" />
from jria where ID in
<foreach item="item" index="index" collection="ids"
open="(" separator="," close=")">
#{item}
</foreach>
</select>