Mybatis批量更新的两种方式
前言
在使用Mybatis框架的过程中,经常会通过构建动态SQL来处理批量插入，批量更新数据等相关操作，本文将以批量更新为例，简单介绍其使用过程
动态SQL元素
if set trim foreach
批量更新
映射方法
int updateOrderItem(List<OrderItem> list);实体类字段
public class OrderItem {
private Integer id;
private Integer orderId;
private Integer productId;
private Integer count;
//省略...
}测试代码
List<OrderItem> list=new ArrayList<>();
OrderItem orderItem=new OrderItem();
orderItem.setCount(66);
orderItem.setId(1);
OrderItem orderItem1=new OrderItem();
orderItem1.setCount(5);
orderItem1.setId(2);
list.add(orderItem);
list.add(orderItem1);
orderItemMapper.updateOrderItem(list);方式一
<update id="updateOrderItem" parameterType="java.util.List">
<foreach collection="list" item="item" separator=";">
update order_item
<set>
<if test="item.orderId != null">
order_id = #{item.orderId},
</if>
<if test="item.productId != null">
product_id = #{item.productId},
</if>
<if test="item.count != null">
count = #{item.count}
</if>
</set>
where id = #{item.id}
</foreach>
</update>对应SQL:
[cn.srblog.dao.OrderItemMapper.updateOrderItem]-==> Preparing: update order_item SET count = ? where id = ? ; update order_item SET count = ? where id = ?
[cn.srblog.dao.OrderItemMapper.updateOrderItem]-==> Parameters: 66(Integer), 1(Integer), 5(Integer), 2(Integer)
[cn.srblog.dao.OrderItemMapper.updateOrderItem]-<== Updates: 1此方式需要允许MySQL的一次执行多条SQL
url=jdbc:mysql://localhost:3306/ssm?characterEncoding=utf-8&allowMultiQueries=true方式二
<update id="updateOrderItem" parameterType="java.util.List">
update order_item
<trim prefix="set" suffixOverrides=",">
<trim prefix="orderId = case" suffix="end,">
<foreach collection="list" item="item">
<if test="item.orderId != null">
when id=#{item.id} then #{item.orderId}
</if>
</foreach>
</trim>
<trim prefix="productId = case" suffix="end,">
<foreach collection="list" item="item">
<if test="item.productId != null">
when id=#{item.id} then #{item.productId}
</if>
</foreach>
</trim>
<trim prefix="count = case" suffix="end,">
<foreach collection="list" item="item">
<if test="item.count != null">
when id=#{item.id} then #{item.count}
</if>
</foreach>
</trim>
</trim>
</update>对应SQL
[cn.srblog.dao.OrderItemMapper.updateOrderItem]-==> Preparing: update order_item set count = case when id=? then ? when id=? then ? end
[cn.srblog.dao.OrderItemMapper.updateOrderItem]-==> Parameters: 1(Integer), 66(Integer), 2(Integer), 5(Integer)
[cn.srblog.dao.OrderItemMapper.updateOrderItem]-<== Updates: 3举报
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