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Data Identification

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).

Keys

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.

Values

Any string that consists of characters: a-z, A-Z, 0-9, ., _, - can be used as a value.

Example of Variable Keys and Values

KeyValueIsKeyDescription
SoftPlcRtId “MyRTNumber3025” True Unique identification of Mervis RT defined by user
GUID 546 True Unique identification of Mervis RT variable generated by Mervis IDE
VariableName “Outside Temperature” False Non-unique variable name defined by user in Mervis IDE

It's recommended to use the following structure of keys and values for new projects and Mervis DB clients.

KeyValueIsKeyDescription
DataSource “MyDS” False Unique identification of the particular data source
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

Example

KeyValueIsKeyDescription
DataSource “SCADASystemXY” False Unique identification of the particular data source
Root “SCADAServer18” 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