Example

local intidspace = 3 -- To use item entries as intid, we need to protect the normal intids by adding some to the entry and when using the entry, removing the addition

local function FindAndDisplayItems(namepart)
    local Q = WorldDBQuery('SELECT entry, name FROM items WHERE name LIKE "%'..namepart..'%" LIMIT 30') -- Search for the item, limit results to max 30
    if(not Q) then -- check query
        return false
    end
    unit:GossipCreateMenu(100, pPlayer, 0)
    unit:GossipMenuAddItem(0, "Find item", 1, 1, "Insert item name part") -- Add search button to top of menu
    repeat -- Loop the results of the query and add as many options as needed
        local entry = Q:GetColumn(0):GetULong()
        local name = Q:GetColumn(1):GetString()
        unit:GossipMenuAddItem(4, name, entry + intidspace, 0)
    until not result:NextRow()
    unit:GossipSendMenu(pPlayer)
    return true
end

local function OnGossipHello(unit, event, player)
    unit:GossipCreateMenu(100, pPlayer, 0)
    unit:GossipMenuAddItem(0, "Find item", 1, 1, "Insert item name part")
    unit:GossipMenuAddItem(7, "Nevermind..", 0, 0)
    unit:GossipSendMenu(pPlayer)
end

local function OnGossipSelect(unit, event, player, id, intid, code)
    if(intid == 0) then
       player:GossipComplete()
       return -- Dont show main menu
    end

    if(intid == 1) then
        if(code) then
            local namepart = code:gsub('\\', ''):gsub('"', '\\"') -- Dont allow backslash, Convert all quotes to escaped quotes (try avoid SQL injection)
            local minlen = 3
            if(namepart:len() < minlen) then
                player:SendAreaTriggerMessage("The name part must be at least "..minlen.." characters long")
            else
                if(FindAndDisplayItems(namepart)) then
                    return -- Showing a submenu, so dont show main menu
                else
                    player:SendAreaTriggerMessage("No results found")
                end
            end
        end
    end

    -- Clicked an item button
    if(intid >= intidspace) then
        player:SendAreaTriggerMessage("Clicked option for item entry "..(intid-intidspace))
    end

    OnGossipHello(unit, event, player) -- Show main menu again
end

RegisterUnitGossipEvent(123, 1, OnGossipHello)
RegisterUnitGossipEvent(123, 2, OnGossipSelect)