In ClearSCADA, the entries in Lists other than Alarms Lists comprise those records that are the result of an SQL query.
SQL is a standardized language used for requesting data from databases. An SQL query can filter, sort, and group data from any table in the database. An SQL query minimizes the loading of any request for data by only retrieving those records that are of interest, rather than all of the records in the database.
In order to customize Lists successfully, you need to:
- Carry out the necessary Preparation.
- Be able to Ascertain which SQL Query is Presently used by a List.
- Understand the SQL Query Structure.
- Be aware of Fields that Perform Special Functions.
For ‘Custom’ Lists with complex queries that include, for example, summary functions (SUM) and/or GROUP BY clauses, only update when a Refresh is issued (see Refresh the Data on a List other than an Alarms List). A Refresh is required if there is no one-to-one correlation between the entries on a List and the Ids or RecordIds that would otherwise identify the records in the ClearSCADA database.
For examples that demonstrate how to customize Lists using an SQL query, see Example Configuration.