mapper foreach 多字段更新

<update id="batchUpdateDynamic">UPDATE userSET <foreach collection="fields" item="field" separator=",">${field.name} = #{field.value}</foreach>WHERE id = #{id}
</update>

// Java实体类
@Data
public class UpdateField {private String name;    // 字段名，如："username", "email"private Object value;   // 字段值
}// Mapper接口
int batchUpdateDynamic(@Param("id") Long id, @Param("fields") List<UpdateField> fields);

版本2：使用Map更灵活

<update id="batchUpdateByMap">UPDATE ${tableName}SET <foreach collection="updateMap" item="value" index="key" separator=",">${key} = #{value}</foreach>WHERE id = #{id}
</update>

// Mapper接口
int batchUpdateByMap(@Param("tableName") String tableName,@Param("id") Long id,@Param("updateMap") Map<String, Object> updateMap);

版本5：使用trim处理逗号

<update id="batchUpdateWithTrim">UPDATE user<trim prefix="SET" suffixOverrides=","><foreach collection="fields" item="field"><if test="field.name != null and field.value != null">${field.name} = #{field.value},</if></foreach></trim>WHERE id = #{id}
</update>

版本6：结合注解使用（更灵活）

// 使用@UpdateProvider实现动态SQL
@UpdateProvider(type = UserSqlProvider.class, method = "buildBatchUpdateSql")
int batchUpdateUser(@Param("id") Long id, @Param("fields") Map<String, Object> fields);// SQL提供类
public class UserSqlProvider {public String buildBatchUpdateSql(Map<String, Object> params) {Long id = (Long) params.get("id");Map<String, Object> fields = (Map<String, Object>) params.get("fields");StringBuilder sql = new StringBuilder("UPDATE user SET ");List<String> updates = new ArrayList<>();for (Map.Entry<String, Object> entry : fields.entrySet()) {// 这里可以对字段名做安全检查if (isValidField(entry.getKey())) {updates.add(entry.getKey() + " = #{fields." + entry.getKey() + "}");}}sql.append(String.join(", ", updates));sql.append(" WHERE id = #{id}");return sql.toString();}private boolean isValidField(String fieldName) {// 定义允许更新的字段Set<String> allowedFields = new HashSet<>(Arrays.asList("username", "email", "age", "status", "phone"));return allowedFields.contains(fieldName);}
}