func (o *querySet) PrepareInsert() (Inserter, error) {
	return newInsertSet(o.orm, o.mi)
}
return a insert queryer.
it can be used in times.
example:
i,err := sq.PrepareInsert()
i.Add(&user1{},&user2{})
package orm
import (
	"fmt"
)
type colValue struct {
	value int64
	opt   operator
}
type operator int
const (
	ColAdd operator = iota
	ColMinus
	ColMultiply
	ColExcept
)
func ColValue(opt operator, value interface{}) interface{} {
	switch opt {
	case ColAdd, ColMinus, ColMultiply, ColExcept:
	default:
		panic(fmt.Errorf("orm.ColValue wrong operator"))
	}
	v, err := StrTo(ToStr(value)).Int64()
	if err != nil {
		panic(fmt.Errorf("orm.ColValue doesn't support non string/numeric type, %s", err))
	}
	var val colValue
	val.value = v
	val.opt = opt
	return val
}
type querySet struct {
	mi       *modelInfo
	cond     *Condition
	related  []string
	relDepth int
	limit    int64
	offset   int64
	groups   []string
	orders   []string
	distinct bool
	orm      *orm
}
var _ QuerySeter = new(querySet)
func (o querySet) Filter(expr string, args ...interface{}) QuerySeter {
	if o.cond == nil {
		o.cond = NewCondition()
	}
	o.cond = o.cond.And(expr, args...)
	return &o
}
func (o querySet) Exclude(expr string, args ...interface{}) QuerySeter {
	if o.cond == nil {
		o.cond = NewCondition()
	}
	o.cond = o.cond.AndNot(expr, args...)
	return &o
}
func (o *querySet) setOffset(num interface{}) {
	o.offset = ToInt64(num)
}
func (o querySet) Limit(limit interface{}, args ...interface{}) QuerySeter {
	o.limit = ToInt64(limit)
	if len(args) > 0 {
		o.setOffset(args[0])
	}
	return &o
}
func (o querySet) Offset(offset interface{}) QuerySeter {
	o.setOffset(offset)
	return &o
}
func (o querySet) GroupBy(exprs ...string) QuerySeter {
	o.groups = exprs
	return &o
}
func (o querySet) OrderBy(exprs ...string) QuerySeter {
	o.orders = exprs
	return &o
}
func (o querySet) Distinct() QuerySeter {
	o.distinct = true
	return &o
}
func (o querySet) RelatedSel(params ...interface{}) QuerySeter {
	if len(params) == 0 {
		o.relDepth = DefaultRelsDepth
	} else {
		for _, p := range params {
			switch val := p.(type) {
			case string:
				o.related = append(o.related, val)
			case int:
				o.relDepth = val
			default:
				panic(fmt.Errorf("<QuerySeter.RelatedSel> wrong param kind: %v", val))
			}
		}
	}
	return &o
}
func (o querySet) SetCond(cond *Condition) QuerySeter {
	o.cond = cond
	return &o
}
func (o *querySet) Count() (int64, error) {
	return o.orm.alias.DbBaser.Count(o.orm.db, o, o.mi, o.cond, o.orm.alias.TZ)
}
func (o *querySet) Exist() bool {
	cnt, _ := o.orm.alias.DbBaser.Count(o.orm.db, o, o.mi, o.cond, o.orm.alias.TZ)
	return cnt > 0
}
func (o *querySet) Update(values Params) (int64, error) {
	return o.orm.alias.DbBaser.UpdateBatch(o.orm.db, o, o.mi, o.cond, values, o.orm.alias.TZ)
}
func (o *querySet) Delete() (int64, error) {
	return o.orm.alias.DbBaser.DeleteBatch(o.orm.db, o, o.mi, o.cond, o.orm.alias.TZ)
}