Virtual columns (joined columns)

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Virtual columns are a deprecated feature of USoft 9.1. See the "Alternative solutions" help topic for up-to-date techniques to achieve the same effect.

A virtual column or joined column is a column that does not actually exist in the database, but takes its value at the USoft level by copying a stored column value from a corresponding record in a parent table. The virtual column itself is defined in the child table.

Example

A TRAVELLER table stores information about travellers, identifying each traveller by a PERSON_ID number. TRAVELLER is the child table of a relationship with parent table PERSON.

On the basis of the PERSON_ID number, you can find the family name of each traveller in the PERSON parent table. You can create a FAMILY_NAME virtual column in TRAVELLER. As a result, when processing TRAVELLER records, USoft will automatically "borrow" the corresponding family name from the PERSON table. In the database, family names are not stored in the TRAVELLER table but only in the PERSON table.

 

 

collapseAlternative solutions
collapseUnderstanding virtual columns
collapseHow to define a virtual column

 

 

See also

Tables

Columns

Relationships