*`db_instance_class` - (Required) Instance type. For details, see [Instance type table](https://intl.aliyun.com/help/doc-detail/26312.htm?spm=a3c0i.o26228en.a3.2.bRUHF3).
- [5, 2000] for MySQL/PostgreSQL/PPAS HA dual node edition;
- [20,1000] for MySQL 5.7 basic single node edition;
- [10, 2000] for SQL Server 2008R2;
- [20,2000] for SQL Server 2012 basic single node edition
Increase progressively at a rate of 5 GB. The unit is GB. For details, see [Instance type table](https://intl.aliyun.com/help/doc-detail/26312.htm?spm=a3c0i.o26228en.a3.3.bRUHF3).
*`instance_charge_type` - (Optional) Valid values are `Prepaid`, `Postpaid`, The default is `Postpaid`.
*`period` - (Optional) The time that you have bought the resource, in month. Only valid when instance_charge_type is set as `PrePaid`. Value range [1, 12].
*`zone_id` - (Optional) Selected zone to create database instance. You cannot set the ZoneId parameter if the MultiAZ parameter is set to true.
*`multi_az` - (Optional) Specifies if the database instance is a multiple Availability Zone deployment.
*`db_instance_net_type` - (Optional) Network connection type of an instance. Internet: public network; Intranet: private network
*`allocate_public_connection` - (Optional) If set to true will applies for an Internet connection string of an instance.
*`instance_network_type` - (Optional) VPC: VPC instance; Classic: classic instance. If no value is specified, a classic instance will be created by default.
*`vswitch_id` - (Optional) The virtual switch ID to launch in VPC. If you want to create instances in VPC network, this parameter must be set.
*`master_user_name` - (Optional) The master user name for the database instance. Operation account requiring a uniqueness check. It may consist of lower case letters, numbers and underlines, and must start with a letter and have no more than 16 characters.
*`master_user_password` - (Optional) The master password for the database instance. Operation password. It may consist of letters, digits, or underlines, with a length of 6 to 32 characters.
*`preferred_backup_time` - (Optional) Backup time, in the format ofHH:mmZ- HH:mm Z.
*`backup_retention_period` - (Optional) Retention days of the backup (7 to 730 days). The default value is 7 days.
*`security_ips` - (Optional) List of IP addresses under the IP address white list array. The list contains up to 1,000 IP addresses, separated by commas. Supported formats include 0.0.0.0/0, 10.23.12.24 (IP), and 10.23.12.24/24 (Classless Inter-Domain Routing (CIDR) mode. /24 represents the length of the prefix in an IP address. The range of the prefix length is [1,32]).
*`db_mappings` - (Optional) Database mappings to attach to db instance. See [Block database](#block-database) below for details.
*`db_name` - (Required) Name of the database requiring a uniqueness check. It may consist of lower case letters, numbers and underlines, and must start with a letter and have no more than 64 characters.