Every variable stored in Mervis DB is identified by set of keys and values. Combination of of keys and values marked with attribute “IsKey=true” defines unique identification of variable (equivalent to primary key known from SQL world).
Any string that consists of characters: a-z, A-Z, 0-9, ., _, - can be used as a key. The key must not start with underscore (“_”) character and must not be empty.
Any string that consists of characters: a-z, A-Z, 0-9, ., _, - can be used as a value.
It's recommended to use the following structure of keys and values for new projects and Mervis DB clients.
| Key | Value | IsKey | Description |
|---|---|---|---|
| DataSource | “MyDS” | False | Unique identification of the particular data source type. |
| Root | “MyDsServer1” | True | Unique identification of the particular Mervis DB client. |
| Guid | “var546” | True | Unique identification of variable generated by Mervis DB client. |
| Level1 | “MyLevel1Id” | False | |
| Level2 | “MyLevel2Id” | False | |
| Level3 | “MyLevel3Id” | False | |
| Level4 | “MyLevel4Id” | False | |
| Level5 | “MyLevel5Id” | False | |
| Name | “My Variable” | False | |
| Unit | “m3” | False |
| Key | Value | IsKey | Description |
|---|---|---|---|
| DataSource | “SCADASystemXY” | False | Unique identification of the particular data source type. |
| Root | “Server18” | True | Unique identification of the particular Mervis DB client. |
| Guid | “aaaaa-bbbbb-ccccc-ddddd-eeeee” | True | Unique identification of variable generated by Mervis DB client. |
| Level1 | “SiteNr500” | False | |
| Level2 | “Building A” | False | |
| Level3 | “Floor 7” | False | |
| Level4 | “Room 17” | False | |
| Level5 | “SouthEast” | False | |
| Name | “Indoor Temperature” | False | |
| Unit | “C” | False |