Please suggest a standard method to restrict loss making sales orders i.e. if a material is purchased at Rs 100 it can not sold less than 100 after all discount
There is no such thing by standard. You have choice to sell item with 0 price.
You can make some customization, but you will still have a problem. What cost you want to use in comparison, actual or expected?
Even if you can make this comparison, you can get the case when currently price is greater than the cost, but when you post the charge for this item, cost can be greater than the price. If you use production, situation is even worse.
I made the same customization a few time for my specific clients, but there must always be more prerequisites in the work and I don't like this. You can use Sales Prices for each item; your sales people need to prevent loss in this configuration. Your people need to use only these prices when prepare sales orders.
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