This table contains coupon definitions
| Column Name | Type | Properties | Docu |
| couponid | string:32 | Primary-Key | |
| description | string | NULL-able | short description of the coupon for internal use |
| validfrom | int64 | Validity period of the coupon. | |
| validtill | int64 | ||
| amountuse | int32 | NULL-able | How often it can be used, if NULL it is unlimited. |
| ticketsperorder | int32 | NULL-able | How many tickets per order can be changed, NULL for unlimited. |
| flags | string | NULL-able | Filter: who can use this coupon. |