If you don't want to add an extra value to your data binded list then use this code:
Template:
<select [(ngModel)]="d" style="width: 100%;" (change)="databaseChange($event.target.value)">
<option [value]="null">Select Database</option>
<option *ngFor="let g of databases;" [ngValue]="g">{{g}}</option>
</select>
Ts:
d = null;