title: How To Solve Grails Error Repeated column in mapping for entity? on Existing Postgresql Database
body: <p>Hi i have this following Domain in Grails</p>
  
  <pre>
  class Customer {
      static mapping = {
           table 'customer'
           // version is set to false, because this isn't available by default for legacy databases
           version false
           id column:'customerid' //generator:'identity', 
      }
      Long customerid
      Long customergroupid
      String username
      String password
      String name
      String street
      String city
      String province
      String postcode
      String country
      Date dateregistered
      String balance
      Long parentid
      String parentrebate
      String metapath
      Long metalevel
      Integer smsreplystatus
      Integer status
      String reversalurl
  
      static constraints = {
          customerid(insert:false,update:false)
          customergroupid(max: 9999999999L)
          username(size: 1..20, blank: false)
          password(size: 1..32, blank: false)
          name(size: 1..20, blank: false)
          street(size: 0..50)
          city(size: 0..20)
          province(size: 0..20)
          postcode(size: 0..5)
          country(size: 0..20)
          dateregistered(nullable: true)
          balance()
          parentid(max: 9999999999L)
          parentrebate()
          metapath(size: 1..255, blank: false)
          metalevel(max: 9999999999L)
          smsreplystatus(max: 99999)
          status(max: 99999)
          reversalurl(size: 0..50)
      }
      String toString() {
          return "${customerid}" 
      }
  }
  </pre>
  
  <p>i have current database with existing data, and has mapping to GORM with GRAG but i'm getting this error</p>
  
  <pre>
  Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionManager': Cannot resolve reference to bean 'sessionFactory' while setting bean property 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory': Invocation of init method failed; nested exception is org.hibernate.MappingException: Repeated column in mapping for entity: postgresql.Customer column: customerid (should be mapped with insert="false" update="false")
      ... 23 more
  Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory': Invocation of init method failed; nested exception is org.hibernate.MappingException: Repeated column in mapping for entity: postgresql.Customer column: customerid (should be mapped with insert="false" update="false")
  </pre>