Link-1 and Link-2

The sub-lists are used to create and manage links that are directed at the relation table of the relation displayed in the header form or originate from there (Basically, links to all database tables can be created here, however, when the relation in the header form is selected, only the links from or to the corresponding relation table are displayed in the sub-list)

Link name of the link between two tables
Table-1 name of the primary table
Key-1 name of the key field in the primary table
Table-2 name of the secondary table
Key-2 name of the key field in the secondary table
>Check Value controls deleting data records in the primary table
>Delete Flag controls actions in the secondary table when data records in the primary table are deleted
>Outer Join outer join flag
<Check Value controls deleting data records in the secondary table
<Delete Flag controls actions in the primary table when data records in the secondary table are deleted
<Outer Join outer join flag
Title opbject title
Comment comment to the link record

Form opens the Link Data form

Link

Name of the link between two database tables

attribute master attribute for link (T_CONSTRAINT)
type, entry string, entry required
max. no. of characters 20
selection tool no
multilingual field no

A link's name is the unique ID of the link object within the application's data model.

Table-1

The name of the table where the link originates

attribute master attribute for link (T_CONSTRAINT)
type, entry string, entry required
max. no. of characters 13
selection tool menu with all existing tables (separated for master, relation or type table)
multilingual field no
hyperlinmk opens the model object of the registered table in an own form

You can enter (or select from the menu) only existing database tables.

Key-1

Name of the key field in Table 1

attribute master attribute for link (T_CONSTRAINT)
type, entry string, entry required
max. no. of characters 255
selection tool menu with all fields of the table 1
multilingual field no

The key is used to uniquely identify records in Table 1 of the link.

Names of Key fields may contain spaces, and several fields can be selected as Key fields. DataView then generates a string of comma-separated field names. <<CLEAR >> in the selection tool deletes the list of Key fields.

Only indexed fields should be used as keys.

Attention! Multilingual and system fields may not be used as keys in links.

More information: -> Key fields for links

Table-2

The name of the link's target table

attribute master attribute for link (T_CONSTRAINT)
type, entry string, entry required
max. no. of characters 13
selection tool menu with all existing tables (separated for master, relation or type table
multilingual field no
hyperlink opens the model object of the registered table in an own form

You can enter (or select from the menu) only existing database tables.

Key-2

The name of the Key field in Table 2

attribute master attribute for link (T_CONSTRAINT)
type, entry string, entry required
max. no. of characters 255
selection tool menu with all fields of the table 2
multilingual field no

The key is used to uniquely identify records in Table 2 of the link.

Names of Key fields may contain spaces, and several fields can be selected as Key fields. DataView then generates a string of comma-separated field names. <<CLEAR >> in the selection tool deletes the list of Key fields.

Only indexed fields should be used as keys.

Attention! Multilingual and system fields may not be used as keys in links.

More information: -> Key fields for links

>Check value

Value tested against the number of records in Table 2 when a record is deleted in Table 1

attribute master attribute for link (T_CONSTRAINT)
type, entry Integer, entry required
max. no. of characters 3
selection tool no
multilingual field no

The Check Value determines when the user can delete a record from Table 1 which is linked to records in Table 2. If the number of linked records in Table 2 is smaller than the Check Value, the record can be deleted from Table 1.

Entry:

0
deletion always possible

n

deletion only possible if the number of dependent child records is lower than n

>Delete

Controls Table 2's behavior when records are deleted in Table 1

attribute master attribute for link (T_CONSTRAINT)
type, entry string, entry required
max. no. of characters 1
selection tool menu
multilingual field no

Entry:

- (default)
Linked record in Table 2 is not deleted

D
Linked record in Table 2 is deleted

N
DataView places an empty entry in the Key field of the child record. The record itself is retained (and can be relinked later).

When master tables are linked to themselves (e.g. to display item or usage lists), entire structures could be deleted recursively. For safety's sake, DataView moves anything deleted recursively to the trash first.

More information: -> Automatically deleting dependent elements

>Outer-Join

Outer Join flag, affects data display in link masks

attribute master attribute for link (T_CONSTRAINT)
type, entry logical
max. no. of characters 3
selection tool no
multilingual field no

Entry:

> ON
Makes an outer join for links from Table 1 to Table 2 during search queries (TABLE1 WHERE TABLE2.KEY=TABLE1.KEY(+)).

More information: -> Controlling display with outer joins

<Check value

Value tested against the number of records in Table 1 when a record is deleted in Table 2

attribute master attribute for link (T_CONSTRAINT)
type, entry Integer, entry required
max. no. of characters 3
selection tool no
multilingual field no

The Check Value determines when the user can delete a record from Table 2 which is linked to records in Table 1. If the number of linked records in Table 1 is smaller than the Check Value, the record can be deleted from Table 2.

Entry:

0
deletion always possible

n
deletion only possible if the number of dependent child records is lower than n

More information: -> Checking for dependent elements

<Delete (flag)

Controls Table 1's behavior when records are deleted in Table 2

attribute master attribute for link (T_CONSTRAINT)
type, entry string, entry required
max. no. of characters 1
selection tool menu
multilingual field no

Entry:

- (default)
Linked record in Table 1 is not deleted

D
Linked record in Table 1 is deleted

N
DataView places an empty entry in the Key field of the child record. The record itself is retained (and can be relinked later).

When master tables are linked to themselves (e.g. to display item or usage lists), entire structures could be deleted recursively. For safety's sake, DataView moves anything deleted recursively to the trash first.

More information: -> Automatically deleting dependent elements

<Outer-Join

Outer Join flag, affects data display in link masks

attribute master attribute for link (T_CONSTRAINT)
type, entry logical
max. no. of characters 3
selection tool no
multilingual field no

Entry:

> ON
Makes an outer join for links from Table 2 to Table 1 during search queries (TABLE2 WHERE TABLE1.KEY=TABLE2.KEY(+)).

More information: -> Controlling display with outer joins

Object Title

A links title

attribute master attribute for link (T_CONSTRAINT)
type, entry string, entry required
max. no. of characters 20
selection tool no
multilingual field yes

The title is used in error messages.

Note! You should always give your objects a title. If you don't, error messages will only contain the object's key, and you won't be able to find the object in a Search mask.

Comment

Comment on the link record

attribute master attribute for link (T_CONSTRAINT)
type, entry string, entry optional
max. no. of characters 255
selection tool no
multilingual field no

Form

Opens the Link Data form for the marked record.