Welcome to the ClearSCADA Guide to Working with SQL. This guide is designed for use by engineers that have SQL programming experience. This is not a comprehensive guide to SQL, but provides generic information about the use of key aspects of SQL within ClearSCADA. For more information about SQL, see the SQL technical reference online Help, and see Implementation of SQL in ClearSCADA.
NOTE: ClearSCADA uses SQL-92 revision of the SQL standard, with the addition of some custom syntax, which is documented in the relevant sections where it is used.
The most common SQL operation in ClearSCADA is the query that allows you to access and display data from the database. This guide provides you with details of the following key aspects of SQL within ClearSCADA:
- Introduction to SQL Query Structure
- SQL Parsing and Verification
- SQL Execution
- SQL Join Optimization
ATTENTION: SQL queries should be written by engineers who have the appropriate experience and knowledge of the SQL language. Running a badly designed SQL query can have an adverse affect on the system. All queries should include suitable restrictions to limit the number of records that are retrieved from the database. An SQL query that queries vast amounts of data will affect the performance of the server while that query executes.
Further Information
SQL Query and List Problems in the ClearSCADA Guide to the Server Status Tool.
Inefficient SQL Queries in the ClearSCADA Guide to the Server Status Tool.
Avoid using the underscore character ( _ ) in the names of database items: see Naming Restrictions in the ClearSCADA Guide to Core Configuration.