java - How to use join tables with hibernate -

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i having difficulty using hibernate select using join tables represent many many.

i have following 3 tables (bold represents links / keys)

user {id, username, password}

group {id, name, scpid}

join table = member {id, groupid, username}

so have scenario in dao user , group want available groups , available members respectively.

this means need provide mapping unsure how this. far groups user have tried complains duplicate username

@manytomany(fetch = fetchtype.lazy, cascade = cascadetype.all) @jointable(name = "member", joincolumns = {@joincolumn(name = "username", nullable = false, updatable = false)}, inversejoincolumns = {@joincolumn(name = "username", nullable = false, updatable = false)}) public set<group> getgroups() {     return usergroups; }  public void setgroups(set<group> usergroups) {     this.usergroups = usergroups; }

can me in identifying how solve please?

thanks

according provided code snippet both @joincolumn's name attribute having username value.


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