func (limit Limit) Build(builder Builder) {
	if limit.Limit != nil && *limit.Limit >= 0 {
		builder.WriteString("LIMIT ")
		builder.AddVar(builder, *limit.Limit)
	}
	if limit.Offset > 0 {
		if limit.Limit != nil && *limit.Limit >= 0 {
			builder.WriteByte(' ')
		}
		builder.WriteString("OFFSET ")
		builder.AddVar(builder, limit.Offset)
	}
}

// MergeClause merge order by clauses
func (limit Limit) MergeClause(clause *Clause) {

						if rv.Len() == 0 {
							builder.AddVar(builder, nil)
						} else {
							for i := 0; i < rv.Len(); i++ {
								if i > 0 {
									builder.WriteByte(',')
								}
								builder.AddVar(builder, rv.Index(i).Interface())
							}
						}
					default:
						builder.AddVar(builder, expr.Vars[idx])
					}
				}
			} else {
				builder.AddVar(builder, expr.Vars[idx])
			}

			idx++

	if len(set) > 0 {
		for idx, assignment := range set {
			if idx > 0 {
				builder.WriteByte(',')
			}
			builder.WriteQuoted(assignment.Column)
			builder.WriteByte('=')
			builder.AddVar(builder, assignment.Value)
		}
	} else {
		builder.WriteQuoted(Column{Name: PrimaryKey})
		builder.WriteByte('=')
		builder.WriteQuoted(Column{Name: PrimaryKey})
	}
}

// MergeClause merge assignments clauses

type Writer interface {
	WriteByte(byte) error
	WriteString(string) (int, error)
}

// Builder builder interface
type Builder interface {
	Writer
	WriteQuoted(field interface{})
	AddVar(Writer, ...interface{})
	AddError(error) error
}

// Clause
type Clause struct {
	Name                string // WHERE
	BeforeExpression    Expression
	AfterNameExpression Expression

		}
		builder.WriteByte(')')

		builder.WriteString(" VALUES ")

		for idx, value := range values.Values {
			if idx > 0 {
				builder.WriteByte(',')
			}

			builder.WriteByte('(')
			builder.AddVar(builder, value...)
			builder.WriteByte(')')
		}
	} else {
		builder.WriteString("DEFAULT VALUES")
	}
}

// MergeClause merge values clauses
func (values Values) MergeClause(clause *Clause) {