Select MAX from multiple Tables

I have four tables, and each table has a date column in it. I am trying to get MAX date of these four date columns.

    DateTime maxDate = ((from stockIn in db.StockIns select stockIn.StockInDate)
.Union(from stockOut in db.StockOuts select stockOut.StockOutDate)
.Union(from stockC in db.StockClearances select stockC.StockClearanceDate)
.Union(from stockR in db.StockRejections select stockR.StockRejectionDate))
.Max().Value; 

Is this the simplest way ?

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Thanks in advance

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If that's the way your data is stored, that's pretty much as simple as it gets.

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I wouldn't use UNION for this problem as the query may have poor performance. Union of 4 tables and then sorting (to get the Max) might be really slow with big tables.

Either get 4 MaxDates from 4 queries and find max of them in the application or use 4 subqueries to get these 4 MaxDates and then either a (SQL syntax) CASE WHEN or a UNION of these results (which would be only 4 rows) and a MAX().

No idea how to translate either from SQL to Linq-to-sql ...

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Ideally you would have your Stock all stored in one table, with linkages to other tables that say whether its In, Out, Clearance or Rejections. Then you could simply do a MAX on the one table.