SQL Overview
Structured Query Language (SQL) is a standard language that is used by relational databases to retrieve, update, and manage data. Although it provides the common syntax for applications to use, it does not provide a common application program interface (API). Open Database Connectivity (ODBC) is Microsoft's standard API for accessing, viewing, and modifying data from a variety of relational databases.
To provide access to SQL data sources through the ODBC API, iFIX® allows you to use the following: the iFIX SQL Interface option, called iFIX ODBC, and Microsoft® Visual Basic® for Applications through DAO or RDO.
iFIX Paths to SQL Data Sources
Both of these options allow you to systematically:
- Collect and write real-time process data to one or more relational databases.
- Read data stored in the relational database and write it back to the iFIX process database.
- Delete data in relational database tables.
- Back up data and SQL commands to disk if the network fails to maintain a connection to the server or if the server fails.
- Execute backed up SQL commands automatically when the connection to the server is re-established.
Although you can use either VBA or iFIX ODBC to access SQL data sources, each one has specific capabilities that should be considered when making a choice. In many cases, it will be quicker and easier to write scripts in the Visual Basic Editor (VBE) that access and manipulate SQL data sources.
As an alternative, iFIX ODBC requires no knowledge of VBA scripting and allows you to perform all of your SQL tasks. For example, if you want to ensure that your database receives deterministic data, you should use the database blocks available through iFIX ODBC. When using database blocks, the data is sent to the database at scan time with no delays.
