kdb q Rank Error

Rank errors happen when you attempt to call a function and supply too many parameters. There is also a particularly tricky variation of this where you try to use default parameters to a qsql query. The parser gets confused and does not recognise them as parameters. As shown below:

/ simple case of too many arguments
q)f:{x+1}
q)f[8;9]
'rank
		
q)/ tricky case where parser is getting confused by default parameters.		
q)t:([] a:1 2 3; b:4 5 6)
q)f:{select from t where a=x,b=y}
q)f[1;4]
'rank

q) / force it to work by specifying them
q)f:{[p;q] select from t where a=p,b=q}
q)f[1;4]
a b
---
1 4

See Also