Database Table Tag

Introduction

The Database Table Tag stores an application specific database table. System Integrators can use database tables to store application specific information, for example:

Batch results
Names of products in a silo

The columns in the Database Table are edited using the Database Table Editor.

Configuration Properties

The Database Table Tag supports the configuration properties of the Core Tag plus these properties:

Property	Type	Version	Description
RowLimit	UDINT	3.35	The maximum number of rows allowed in the table.
SQLTableComment	STRING	3.35	A comment string about the table. The comment string will appear in SQL metadata.
SQLTableName	STRING	3.35	The name of the table in SQL Commands. The value must be a valid SQL Identifier.

SQLTableName Property

The SQLTableName property defines the name of the table in an SQL Statement.

When an SQL command references a Database Table Tag, you must qualify the name with the schema name "DatabaseTable". For example:

SELECT *
FROM DatabaseTable.<SQLTableName>

Where <SQLTableName> is the value of the SQLTableName property.

For more information about the format of SQL Commands, see Fernhill SCADA SQL.

To include spaces or special characters in the table name, use a delimited table name:

"Name With Spaces !"

The SQLTableName property must be configured correctly otherwise the Database Table will not be visible from SQL. For example:

The SQLTableName must be a valid SQL Identifier.
The SQLTableName must not be blank.
The SQLTableName must be 128 characters or fewer.
The SQLTableName must not duplicate the SQLTableName of another Database Table Tag.

Data Properties

The Database Table Tag supports the data properties of the Core Tag, plus these data properties:

Property	Type	Description
TableState	UINT	A code providing information about the table.
ErrorMessage	WSTRING	The errors in configuration of the Database Table.

TableState Property

The TableState property provides information about the configuration of the table:

TableState	Description
0	Initial state. Should not appear in normal operation.
1	Invalid table name. The SQLTableName property is not a valid SQL Identifier.
2	No table name defined. The SQLTableName property is blank.
3	Table name too long. The SQLTableName is more than 128 characters.
4	Duplicate table name. The SQLTableName is a table name that is used by another Database Table.
15	The Database Table is configured correctly and visible to SQL statements.

Tag Commands

The Database Table Tag does not support any tag commands.

Relationships to Other Tag Types

The Database Table Tag builds on the features of these tag types:

Common Core Tag

Further Information

Core Driver

For information about all the tag types provided by the core driver.

Fernhill SCADA Structured Query Language (SQL)

To learn about SQL in Fernhill SCADA.

SQLCommand Data Object

To learn how to access a Database Table Tag from an IEC 61131-3 code.

Glossary

For the meaning of terms used in Fernhill SCADA.