Description:
Attach the grouping record action to a cursor and return the original cursor while writing the grouped subsets to a sequence of bin files.
Syntax:
cs.groupn(x;F)
Note:
The function attaches a computation, which groups records of cursor cs by grouping expression x and writes the grouped subsets to sequence of bin files F, and returns the original cursor cs.
This is a delayed function.
Parameter:
|
cs |
A cursor |
|
x |
Grouping expression |
|
F |
A sequence of bin file objects |
Return value:
Cursor
Example:
|
|
A |
|
|
1 |
=demo.cursor("select NAME,GENDER,DEPT,BIRTHDAY from EMPLOYEE") |
Return a cursor. |
|
2 |
=[file("f_dept.btx"),file("m_dept.btx")] |
A sequence of bin file objects. |
|
3 |
=A1.groupn(if(GENDER=="F",1,2);A2) |
Attach a computation to cursor A1, which puts records where GENDER is F into the first group and the other records into the second group and writes the grouped subsets into a sequence of bin files in order, and return the original cursor. |
|
4 |
=A3.skip() |
Data will be really written to a bin file after the data fetching operation is really executed on cursor A1. |