T.derive()
Description:
Add a composite table’s fields to a table sequence or a cursor according to the latter’s key values.
Syntax:
T.derive(A/cs,x:C,…;wi,...)
Note:
The function adds one or more fields of composite table T to table sequence A or cursor/multicursor cs according to key values of the latter. It returns a table sequence when adding fields to a table sequence; and returns a cursor when adding fields to an ordinary cursor or a multicursor.
Parameters:
|
T |
A composite table |
|
A/cs |
A table sequence/cursor/multicursor |
|
x |
Field value |
|
C |
Column alias;can be absent |
|
wi |
Filtering condition; separate multiple conditions, which should be met at the same time, by comma(s). |
Return value:
A table sequence/cursor
Example:
|
|
A |
|
|
1 |
=file("D:\\emp10.ctx") |
|
|
2 |
=A1.create() |
Open a composite table
|
|
3 |
=demo.query("select EID from EMPLOYEE").keys(EID) |
|
|
4 |
=A2.derive (A3,NAME,GENDER) |
Add fields of the composite table to A3’s table sequence by the latter’s key values
|
|
5 |
=demo.query("select EID from EMPLOYEE").cursor() |
|
|
6 |
=A2.derive(A5,NAME:NAME,GENDER:GENDER).fetch() |
Add fields of the composite table to A5’s cursor by the latter’s key values
|
|
7 |
=file("D:/employees.ctx").create() |
Open a composite table |
|
8 |
=demo.query("select EID,DEPT from employee").keys(EID) |
Return a table sequence with EID as the key |
|
9 |
=A7.derive(A8,NAME:name,GENDER;GENDER=="M") |
Add certain fields of A7’s composite table to A8’s table sequecne according to key values; filtering condition over A7 is GENDER=="M" |
