Here’s how to use v() function.
Description:
Get the primary key value of the record pointed by a referencing field.
Syntax:
v.v()
Note:
If v is a record with a key set, the function will return its primary key value; if v is a record without a key set, the function will return a sequence composed of all its field values; if v isn’t a record, the function will return v itself.
This function is used to get the primary key value of the record pointed by a referencing field. Since a referencing field can switch between a referenced record and its key value through the switch() function, the v() function can be used to distinguish a record from a key value.
v may be a record, a sequence or a number.
Parameter:
|
v |
A record, a sequence or a number |
Return value:
The primary key value of the record pointed by a referencing field
Example:
|
|
A |
|
|
1 |
=demo.query("select * from EMPLOYEE") |
|
|
2 |
=A1(1).EID.v() |
1; because the value of the EID field is a single number, the value itself is returned. |
|
3 |
=A1(1).v() |
[1, Rebecca，Moore，F，California，1974-11-20，2005-03-11，R&D，7000]; return a sequence composed of all field values of A1(1) because A1 doesn’t set a key. |
|
4 |
=demo.query("select * from DEPARTMENT ").keys(MANAGER) |
|
|
5 |
=A1.switch(DEPT,A4:DEPT) |
Switch the DEPT field into a referencing field pointing to the record of DEPARTMENT. |
|
6 |
=A1(1).DEPT.v() |
2; here, DEPT is a reference field whose value is record, therefore, the primary key value of the referenced record will be returned. |
|
7 |
=A4.keys(DEPT,MANAGER) |
Set DEPT and MANAGER as the key of A4. |
|
8 |
=A1(1).DEPT.v() |
[R&D,2]; return the key value of the record pointed by "DEPT"; since there are two key fields, a sequence of primary key value will be returned. |
Related function: