@ManyToMany(cascade = CascadeType.PERSIST, fetch = FetchType.LAZY)
@JoinTable(name = "_UserRole", joinColumns = {
@JoinColumn(name = "tf_userId", referencedColumnName = "tf_userId") }, inverseJoinColumns = {
// _UserRole 中的字段名， _Role 中的关联字段名
@JoinColumn(name = "tf_roleId", referencedColumnName = "tf_roleId") })
public Set<_Role> tf_Roles;select group_concat(tf_roleId ,',', tf_roleName SEPARATOR '|||') from _Role得到的结果为： ‘0000,管理员|||0005,市级管理员|||0010,查询角色‘ ，里面一共有三行数据，每行用 ‘|||‘分隔，行中的字段用 ‘,‘号来分隔。
SELECT
_t9035.tf_userId AS tf_userId,
_t9035.tf_userName AS tf_userName,
_t9035.tf_loginName AS tf_loginName,
_t9011.tf_departmentId AS P__t9011___tf_departmentId,
_t9011.tf_departmentId AS _t9011___tf_departmentId,
_t9011.tf_name AS _t9011___tf_name,
(SELECT
GROUP_CONCAT(tf_roles0_.tf_roleId,
',',
role1_.tf_roleName SEPARATOR '|||')
FROM
_UserRole tf_roles0_
INNER JOIN
_Role role1_ ON tf_roles0_.tf_roleId = role1_.tf_roleId
WHERE
tf_roles0_.tf_userId = _t9035.tf_userId)
FROM
_User _t9035
LEFT OUTER JOIN
_Department _t9011 ON _t9011.tf_departmentId = _t9035.tf_departmentId
ORDER BY _t9011.tf_departmentId , tf_loginName 以上查询查询语句为拼接而成，拼接过程比较复杂，这里就不讲解了。
常规功能和模块自定义系统 (cfcmms)—027开发日志(创建ManyToMany的column2)
原文：http://blog.csdn.net/jfok/article/details/50419027