Count Rows over lists of tables

[Ben_R]

Hi, i have a variable where each item is a table.  How can i return a list of their number of rows.  For example:

a,b,c,d are tables with # of rows 1,2,9,10 respectively

y: `a`b`c`d

z: select count i for each table in y

z:1 2 9 10

y join z

a 1

b 2

c 9

d 10

thanks

[jwbuitenhuis]

exec gives you the query result as a list, if you know there will be only one you can run 'first exec':

y:{([]n:x?100)}each 1 2 9 10

{first exec count i from x}each y

or 

`a`b`c`d!{first exec count i from x}each y

does that help at all?

[miketurk86]

If the tables are stored in the variable y, then you may use

y!count each value each y

To create a dictionary of the table names and their respective number of rows.

[Flying]

q)a:([]a:10?10.;b:10?`3)

q)b:([]a:3?10.;b:3?`3)

q)c:([]a:12?10.;b:12?`3)

q)t:`a`b`c

q)t!(count value@)each t

a| 10

b| 3

c| 12