Help expanding code

Getting Started Newbie Questions
#1

Hello all, I am currently creating a little loop that gets a value from a database. What I want to do is expand it so I can do this more than twice (what it currently does now). Any thoughts or suggestions?

My code is:

 local previous={}         local i = 1          local firstvalue= {}         local secondvalue={}         for z=1,2 do         local randtest=math.random(1,4)         previous[z]=randtest         if z==1 then         for row in db:nrows("SELECT \* FROM tableWHERE ID="..randtest)do         firstvalue[z] = row.value1         secondvalue[z] = row.value2         end         else         while randtest==previous[z-1]do         randtest=math.random(1,4)         end         for row in db:nrows("SELECT \* FROM table WHERE ID="..randtest)do         firstvalue[z] = row.value1         secondvalue[z] = row.value2         end         end         end

Apologies about the lack of indentation

#2

It would be helpful to know what you are trying to achieve.  Do you want 2 random rows from the DB if so then do it in SQL

SELECT \* FROM table ORDER BY RANDOM() LIMIT 2
#3

Sorry about not being specific enough. What I want to do is get x number of random rows from a DB and get the values from two columns within that row ie the table is set up like id value1 value2, where each row is unique. I want to store each value into two separate lua tables. Is that better?

#4

This will fill your arrays with 2 random rows

local rowsToReturn = 2 local firstvalue, secondvalue = {}, {} for row in db:nrows("SELECT value1, value2 FROM table ORDER BY RANDOM() LIMIT "..rowsToReturn) do   firstvalue[#firstvalue+1] = row.value1   secondvalue[#secondvalue+1] = row.value2 end
#5

Thank you for that, it’s really simplified things. However it appears that sometines when I launch this it causes the simulator to freeze. Any idea what could be causing it?

#6

No not really (without your full source code and DB it is almost impossible to call)… you will need to debug your code (lots of print statements help a lot) to figure out what is happening.

#7

It would be helpful to know what you are trying to achieve.  Do you want 2 random rows from the DB if so then do it in SQL

SELECT \* FROM table ORDER BY RANDOM() LIMIT 2
#8

Sorry about not being specific enough. What I want to do is get x number of random rows from a DB and get the values from two columns within that row ie the table is set up like id value1 value2, where each row is unique. I want to store each value into two separate lua tables. Is that better?

#9

This will fill your arrays with 2 random rows

local rowsToReturn = 2 local firstvalue, secondvalue = {}, {} for row in db:nrows("SELECT value1, value2 FROM table ORDER BY RANDOM() LIMIT "..rowsToReturn) do   firstvalue[#firstvalue+1] = row.value1   secondvalue[#secondvalue+1] = row.value2 end
#10

Thank you for that, it’s really simplified things. However it appears that sometines when I launch this it causes the simulator to freeze. Any idea what could be causing it?

#11

No not really (without your full source code and DB it is almost impossible to call)… you will need to debug your code (lots of print statements help a lot) to figure out what is happening.