|
At domain level, you
can specify that an external component must generate the unique
values for a domain.
| 1.
|
In the Generate Unique Values drop-down list, specify:
Component. |
| 2.
|
In the field to the right of the drop-down list, specify the
component name, or use the lookup button. |
When a primary key column is
based on this domain, a <TableName>GETSEQUENCENUMBER method
is added to the component definition. Parameters are added for the
other primary key columns.
| 3.
|
(Re-)write the <TableName>GetSequenceNumber() method in
the component code, and let this method provide the sequence
value. |
This method is invoked when
inserting a record.
Example
Consider an ORDERLINES component table with three columns:
|
·
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ORDER_ID, a primary key column with Generate Unique Values set
to No. |
|
·
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ORDERLINE_ID, a primary key column with Generate Unique Values
set to the ORDERLINES component. |
|
·
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AMOUNT, a number column. |
The ORDERLINES component gets
an ORDERLINESGETSEQUENCENUMBER method with two parameters:
| 1.
|
ORDER_ID, Mode: In, Data Type: Long Integer. |
| 2.
|
ORDERLINE_ID, Mode: Out, Data Type: Long Integer. |
If the following SQL statement
is executed:
INSERT INTO ORDERLINES( order_id, amount
)
VALUES( 3341, 159.95 )
The
ORDERLINESGETSEQUENCENUMBER method of the ORDERLINES table
component is invoked to get a new orderline_id within order
3341:
OrderlinesGetSequenceNumber(3341, NULL)
NOTE:
You can also have a component generate the unique values for a
DATABASE table. This way, you can program your own sequence
generation, and you can use non-integer data types.
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