Looping through Table Rows

[#1]

I want to Loop through each row in a table, set variables to the values of each row in order to do some repetitive processing.  Seems like a simple construct that would be used often.  Here is what I thought would work, but for some reason the data coming back doesn't seem to match across the column for each row returned, and as I work through index by third iteration I'm getting nulls on the second column.

BOX:

LOAD * INLINE [BOXName, VOLCnt
"MRC", 49152
"TTN", 49152
"PLT", 12288
"GLD", 12288
"SVR", 12288
"IRN", 12288
];

LET NumRows=NoOfRows('BOX');
FOR i=1 to $(NumRows)
  LET vBox=FieldValue('BOXName',$(i));
  LET vVolCnt=FieldValue('VOLCnt',FieldIndex('BOXName','$(vBox)'));
//do some stuff....
NEXT;

Result set for variables after run:

vBox	vVolCnt
MRC	49152
TTN	12288
PLT	<NULL>
GLD	<NULL>
SVR	<NULL>
IRN	<NULL>

Seems I'm missing something very elementary here

[#2]

What about when you use the value from one to find the row in a different table?

[Anonymous]

Was there any final conclusion on this one? I have an example where I did not use the third parameter, and I got unexpected results. To be safe, and like Henric says here and here, I will use a third parameter; the name of the Table where I expect to find that Field.

[SebSz]

Great solution! Just the count of the variable i should start from 0: 

BOX:

LOAD * INLINE [BOXName, VOLCnt
"MRC", 49152
"TTN", 49152
"PLT", 12288
"GLD", 12288
"SVR", 12288
"IRN", 12288
];

LET NumRows=NoOfRows('BOX')-1;
FOR I=0 to $(NumRows)

LET vBox=Peek('BOXName',$(i));

LET vVolCnt=Peek('VOLCnt',$(i));//do some stuff....
NEXT;

Let vBox= Null();
Let NumRows= Null();
Let I = Null();

[Harry_M]

Like if you still come to this thread to copy and paste the For loop instead of typing it out. 😁