# T.f( C )

Description:

Perform an aggregate operation over an attached table’s column.

Syntax:

T.f(C)

Note:

The function performs an aggregation (function f) over the multiple records corresponding to one value in a specific column of an attached table.

Parameters:

 T An attached table f An aggregate operation performed over the attached table; support count, sum, max, min, avg, top and iterate C An attached table’s column

Example:

 A 1 =create(k1,v1).record([1,10,2,20,3,30,4,40,10,100]) Create a table sequence 2 =create(k1,k2,v2).record([1,1,"a",2,4,"c",2,8,"b"]) Create a table sequence 3 =file("D:/ckv.ctx") 4 =A3.create(#k1,v1) Create the composite table’s base table 5 =A4.attach(table2,#k2,v2) Add an attached table to the base table 6 =A4.append(A1.cursor()) Append data to the base table 7 =A5.append(A2.cursor()) Append data to the attached table 8 =A4.cursor(k1,table2.sum(k2):k2_sum).fetch() Perform a sum operation over each value of column k2 in attached table table2, and name the new column k2_sum 9 =A4.cursor(table2.count(k2)).fetch() Perform count operation over each value of column k2 in attached table table2 10 =A4.cursor(table2.max(k2)).fetch() Perform max operation over each value of column k2 in attached table table2 11 =A4.cursor(table2.min(k2)).fetch() Perform min operation over each value of column k2 in attached table table2 12 =A4.cursor(table2.avg(k2)).fetch() Perform average operation over each value of column k2 in attached table table2 13 =A5.cursor().top(2;k2) Return the records corresponding to the first two smallest values in column k2 in entity table table2 14 =A5.cursor().derive(iterate(~~*2,10):F1).fetch() Perform an iteration over entity table table2