SQl query to Break up rows to batches - sql

Question

I have a table like this
OrderID Product Quantity
1 A 800
2 B 700
3 C 300
I need a select query in order to split the total quantity of 1800 to a number of batches (eg 3) like this
BatchNo Product Quantity
1 A 600
2 A 200
2 B 400
3 B 300
3 C 300
Is there any way to do this as a select query ?
I use SQL 2016

Answer 1

ceiling(cast(row_number()(order by (select 1)) as decimal (10, 2)) / 3) as BatchNo
This should do what you require. Just add it to your select statement. You can change the number you are dividing by splitting it up into more batches.

Answer 2

Imho the fastest way to do this is write for example CLR SqlProcedure that would read data row by row and produce output record every time "batch" has 300 or more using SqlContext.Pipe.SendResultsStart() / SqlContext.Pipe.SendResultsEnd() / SqlContext.Pipe.SendResultsRow() . It is easy to produce output data in single pass with c#, not so much in tsql
public partial class StoredProcedures
{
[Microsoft.SqlServer.Server.SqlProcedure]
public static void MakeBatches()
{
using (var connection = new SqlConnection("context connection=true"))
{
connection.Open();
var command = new SqlCommand(string.Format("SELECT [...]"), connection);
var reader = command.ExecuteReader();
using (reader)
{
var outputRecord = new SqlDataRecord(new SqlMetaData[]
{
new SqlMetaData("BatchNo", SqlDbType.Int),
new SqlMetaData("Product", SqlDbType.Char),
new SqlMetaData("Quantity", SqlDbType.Int)
}
);
SqlContext.Pipe.SendResultsStart(outputRecord);
while (reader.Read())
{
var orderId = reader.GetInt32(0);
var product = (char)reader.GetValue(1);
var quantity = reader.GetInt32(2);
if ([...]) //put some logic here
{
outputRecord.SetInt32(0, batchNo_value_here);
[...] //insert record here
SqlContext.Pipe.SendResultsRow(outputRecord);
}
}
SqlContext.Pipe.SendResultsEnd();
}
}
}
}