In the PROMOTIC system databases are accessed preferably by the PmaAdo object (and by the PmaDatabase object - but this one is now considered obsolete). These objects contain multitude of methods for creating databases and tables, inserting or deleting records in tables, writing and reading values in records, searching and sorting, SQL statements executions, etc. The functionality of the PmaAdo and PmaDatabase objects is bound to purchase of the PmDB licence.
Some components of the PROMOTIC system (Trends and Alarms and Events) also allow to save data into database the system way. The PmaTrendGroup and PmaAlarmGroup objects functionality is not conditioned by purchase of the PmDB licence.
The ADO technology by the Microsoft company allows to access database by available ADO Providers provided by the Microsoft company, by database manufacturers, from third parties, usage of the ADO Provider for standard ODBC, etc. The database (server) connection itself is executed by the ADO Connection object, defined by the ADO ConnectionString string. The ADO Connection object allows to execute SQL statements over thw database. Most SQL statements do not return any data (create/change/delete table, add/change/delete record in the table, etc.). The SQL statement SELECT returns requested data in table form as the ADO Recordset object.
The ADO technology is the fundamental data storage technology used by PROMOTIC components that produce data and need to be saved as history (PmaTrendGroup, PmaAlarmGroup). The ADO technology is also a basic technology used for working with data in database the user way (PmaAdo). The important fact is that the connection itself (ADO Connection) to a specific database (server), defined by the ADO ConnectionString is identical for all PROMOTIC components.
The ADO ConnectionString (http://www.connectionstrings.com) contains all necessary parameters needed by the ADO Connection object for database connection via the selected ADO Provider. The typical parameters are represented for example by connection provider (provider), server address (server), database name (database), login name and password (uid, pwd), etc. The parameter list and exact syntax is defined by the corresponding ADO Provider, parameters may differ by individual ADO Providers. However for the sake of compatibility most providers ADO Provider understand multiple names of the main parameters simultaneously (e.g. the database name can be represented by database, data source, dbq, etc.).
For example: "provider=SQLOLEDB;server=.\SQLEXPRESS;database=pm_data;uid=pm_admin;pwd=pmadmin;"