现在有一张订单表t_stockorder，其拥有id、code、client_id、merchandise_id、merchandise_number、order_date、operator_id这些字段，其中client_id关联t_client表中code字段，merchandise_id关联t_merchandise表的code字段，operator_id关联t_employee表的code字段。
现在要通过SQL语句将订单表中t_stockorder的数据全部查询出来，SQL语句如下所示：
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select so.id, so.code, c. name cname, m. name mname, so.merchandise_number, so.order_date, e. name ename from inventory.t_stockorder so inner join inventory.t_client c on c.code = so.client_id inner join inventory.t_merchandise m on m.code = so.merchandise_id inner join inventory.t_employee e on e.code = so.operator_id |
现在要在mapper映射文件中添加动态Sql语句，一般情况下映射文件中的resultMap元素中只可以有一个association，那如何添加多个association到resultMap中呢？正确代码如下图所示：
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< resultMap id = "StockorderMap" type = "com.lwz.entity.Stockorder" > < id property = "id" column = "id" /> < result property = "code" column = "code" /> < result property = "merchandiseNumber" column = "merchandise_number" /> < result property = "orderDate" column = "order_date" /> < association property = "client" javaType = "Client" resultMap = "ClientResultMap" ></ association > < association property = "merchandise" javaType = "Merchandise" resultMap = "MerchandiseResultMap" ></ association > < association property = "employee" javaType = "Employee" resultMap = "EmployeeResultMap" ></ association > </ resultMap > < resultMap id = "ClientResultMap" type = "com.lwz.entity.Client" > < id property = "code" column = "code" /> < result property = "name" column = "cname" /> </ resultMap > < resultMap id = "MerchandiseResultMap" type = "com.lwz.entity.Merchandise" > < id property = "code" column = "code" /> < result property = "name" column = "mname" /> </ resultMap > < resultMap id = "EmployeeResultMap" type = "com.lwz.entity.Employee" > < id property = "code" column = "code" /> < result property = "name" column = "ename" /> </ resultMap >
<!--通过实体作为筛选条件查询--> < select id = "queryAll" resultMap = "StockorderMap" > select so.id, so.code, c.name cname, m.name mname, so.merchandise_number, so.order_date, e.name ename from inventory.t_stockorder so inner join inventory.t_client c on c.code = so.client_id inner join inventory.t_merchandise m on m.code = so.merchandise_id inner join inventory.t_employee e on e.code = so.operator_id < where > < if test = "id != null" > and id = #{id} </ if > < if test = "code != null and code != ''" > and so.code = #[code] </ if > < if test = "client != null" > and client_id = #{client.code} </ if > < if test = "merchandise != null" > and merchandise_id = #{merchandise.code} </ if > < if test = "merchandiseNumber != null" > and merchandise_number = #{merchandiseNumber} </ if > < if test = "orderDate != null" > and order_date = #{orderDate} </ if > < if test = "employee != null" > and operator_id = #{employee.code} </ if > </ where > </ select > |
resultMap中association的各个属性的含义：
property:映射实体类的字段或属性。 colum:数据库的列名或者列标签别名。 javaTyp:完整java类名或别名。 jdbcType支持的JDBC类型列表列出的JDBC类型。这个属性只在insert,update或delete的时候针对允许空的列有用。 resultMap: 一个可以映射联合嵌套结果集到一个适合的对象视图上的ResultMap。这是一个替代的方式去调用另一个select语句。到此这篇关于MyBatis映射文件resultMap元素中使用多个association的方法的文章就介绍到这了,更多相关MyBatis 多个association内容请搜索以前的文章或继续浏览下面的相关文章希望大家以后多多支持！
原文链接：https://blog.csdn.net/weixin_43894879/article/details/106770531
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