| Navigation: Language Reference > 4 - Entity Declarations > View Structures >====== PROJECT (set view fields) ====== |    |
PROJECT( fields )
| PROJECT | Declares the fields retrieved for the VIEW. |
| fields | A comma delimited list of fields (including prefixes) from the primary file of the VIEW, or the secondary related file named in the JOIN structure, containing the PROJECT declaration. |
The PROJECT statement declares fields retrieved for a relational “Project” operation. A relational “Project” operation retrieves only the specified fields from the file, not the entire record structure.
A PROJECT statement may be declared in the VIEW, or within one of its component JOIN structures. If there is no PROJECT declaration in the VIEW or JOIN structure, all fields in the relevant file are retrieved.
If a PROJECT statement is present in the VIEW or JOIN structure, only the fields explicitly declared in the PROJECT are guaranteed to be retrieved. The contents of any fields that are not contained in PROJECT statements are undefined. Depending on the abilites of the particular database engine you are using, other fields may be retrieved. However, you should not rely on this as future changes or changes in the database driver may preclude these fields from being retrieved.
Example:
Detail FILE,DRIVER('Clarion'),PRE(Dtl) !Declare detail file layout
OrderKey KEY(Dtl:OrderNumber)
Record RECORD
OrderNumber LONG
Item LONG
Quantity SHORT
Description STRING(20) !Line item comment
END
END
Product FILE,DRIVER('Clarion'),PRE(Pro) !Declare product file layout
ItemKey KEY(Pro:Item)
Record RECORD
Item LONG
Description STRING(20) !Product description
Price DECIMAL(9,2)
END
END
ViewOrder VIEW(Detail)
PROJECT(Det:OrderNumber,Det:Item,Det:Description)
JOIN(Pro:ItemKey,Det:Item)
PROJECT(Pro:Description,Pro:Price)
END
END