q)tab:([]col1:`a`b`c;col2:1 2 3)

q)select i,col1,col2 from tab
x col1 col2
-----------
0 a    1
1 b    2
2 c    3
q)
q)exec i from tab where col1=`b
,1

q)tab2:([] index:2 3;col3:"yz")
q)
q)tab2
index col3
----------
2     y
3     z

q)(select index:i,col1,col2 from tab) lj 1!tab2
index col1 col2 col3
--------------------
0     a    1
1     b    2
2     c    3    y

t:([] id:1 2 3)

select from t where i=1

    output--> id:2

t:delete from t where i=1

select from t where i=1

    output--> id:3