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
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
objects functionality is not
conditioned by purchase of the PmDB licence.
Common work with database
It is not suitable to enter column names like Time, Date, No, Desc and so on because these words are often keywords of particular database systems and meaningless errors are often raised on an attempt to use such words.
The maximum number of columns in the table is usually limited by a constant that is often changed when converting between several versions (it is usually increased when converting to a higher version of the database).
The maximum length of column name in the table is usually limited by constant.
Access to databases by using the ADO technology
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 does not return any data (create/change/delete table, add/change/delete record in the table, etc.). The SQL
returns requested data in table form as the ADO Recordset
technology is the fundamental data storage technology used by PROMOTIC components that produce data and need to be saved as history (PmaTrendGroup
). 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.
Database connection parameters: ADO ConnectionString
The ADO ConnectionString
) 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
), 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
For example: "provider=SQLOLEDB;server=.\SQLEXPRESS;database=pm_data;uid=pm_admin;pwd=pmadmin;"
see ADO ConnectionString
List of supported databases:
For next descriptions of database statements see: