KX Community

Well it really depends what you actually want to do. they keyword parse (parse | Reference | kdb+ and q documentation – Kdb+ and q documentation (kx.com)) simply parses an expression into a parse tree, in this case it parses a q-sql statement into a functional select. The output you got, is what your qsql looks like in form of a functional select.

q)parse "select time,sym,bid,ask from t"

?
t
()
0b
time
sym
bid
ask!
time
sym
bid
ask

q)t:([] time:5?.z.p; sym:5?
3; bid:5?10.0; ask:5?10.0)

q)t
time sym bid ask
---------------------------------------------------
2014.11.16D17:25:17.686664320 enf 3.017723 3.927524
2012.10.31D16:48:20.456221120 plh 7.85033 5.170911
2016.10.06D02:12:56.529433024 nni 5.347096 5.159796
2005.07.26D06:48:01.359027808 glc 7.111716 4.066642
2016.10.09D03:08:41.154352640 gkp 4.11597 1.780839

q)eval parse "select time,sym,bid,ask from t"

time sym bid ask
---------------------------------------------------
2014.11.16D17:25:17.686664320 enf 3.017723 3.927524
2012.10.31D16:48:20.456221120 plh 7.85033 5.170911
2016.10.06D02:12:56.529433024 nni 5.347096 5.159796
2005.07.26D06:48:01.359027808 glc 7.111716 4.066642
2016.10.09D03:08:41.154352640 gkp 4.11597 1.780839

However, you don’t actually need to parse/transform your qsql to a functional select inside your function if you don’t really “want” (I recommend using functional selects only if you really need to, i.e. if you need to parameterise your queries)

Here you have a function that takes a table as input and then selects from it using qsql

q){select time,sym,bid,ask from x}[t]

time sym bid ask
---------------------------------------------------
2014.11.16D17:25:17.686664320 enf 3.017723 3.927524
2012.10.31D16:48:20.456221120 plh 7.85033 5.170911
2016.10.06D02:12:56.529433024 nni 5.347096 5.159796
2005.07.26D06:48:01.359027808 glc 7.111716 4.066642
2016.10.09D03:08:41.154352640 gkp 4.11597 1.780839

A very helpful read about functional selects is the Whitepaper about parse trees.

Parse trees and functional forms | White Paper | kdb+ and q documentation – Kdb+ and q documentation (kx.com)

Hope this helps

Alex