Store a column as a string in kdb

Question

I have a table with numerous columns. I'm trying to take the data from one of the columns and return it as a string.

For instance, if I had:

I would like to take column B and store 258 as a string. How would I do this?

score 3 · Accepted Answer · answered Jun 15 '17 at 12:54

3

Like this?

q)raze exec string B from ([] A:1 4 7;B:2 5 8;C:3 6 9)
"258"

Or are you trying to change the type of the column in the table?

q)update string B from ([] A:1 4 7;B:2 5 8;C:3 6 9)
A B    C
--------
1 ,"2" 3
4 ,"5" 6
7 ,"8" 9

answered Jun 15 '17 at 12:54

terrylynch

score 2 · Answer 2 · answered Jun 17 '17 at 01:51

If all your entries are single digit numbers, all you need to do is

.Q.n t.B

Taking your data as an example,

q)show t:([] A:1 4 7;B:2 5 8;C:3 6 9)
A B C
-----
1 2 3
4 5 6
7 8 9
q).Q.n t.B
"258"

Note that .Q.n is simply a string containing the 10 digits:

q).Q.n
"0123456789"

If you want to store the string back in the table, just use update:

q)update .Q.n B from `t
`t
q)t.B
"258"

2 Answers2