General Guidelines for Building a Query
Using SQL statements, you can retrieve information from the columns and rows in a specified table or tables. You are only limited by the amount of memory on your system when determining the number of data rows that you can retrieve from a table.
| Table Name | Description |
|---|---|
| ihTags Table | Contains Historian tag configuration information. |
| ihArchives Table | Contains Historian archive configuration information, plus performance statistics for each archive. |
| ihCollectors Table | Contains configuration and status information for each collector connected to the Historian server. |
| ihMessages Table | Contains Historian messages such as alerts, informational topics, and connection information contained in the audit log. |
| ihRawData Table | Contains collected data for each tag in the Historian server. It contains not just raw data, but also calculated and interpolated data. |
| ihComments Table | Contains the comments associated with the Historian data. |
| ihTrend Table | Another way to look at collected data. Contains a row of data for each unique timestamp. You can use this table to look at your data at a summarized level. You would typically use this table to compare multiple tags with the same timestamp. |
| ihQuerySettings Table | Contains a set of parameters that apply to all queries you make in that session, unless overridden by a WHERE clause. |
| ihCalculationDependencies | Contains the calculation dependencies for tags. |
| ihAlarms Table | Contains collected alarms and events data. |
| ihEnumeratedSets Table | Contains information about enumerated sets. |
| ihEnumeratedStates Table | Contains information about enumerated states. |
| ihUserDefinedTypes Table | Contains information about user-defined data types. |
| ihFields Table | Contains information about fields used in user-defined types. |