This is strange. I am moving a stored proc to a service. The TSQL unions multiple selects. To replicate this I created multiple queries resulting in a common new concrete type. Then I issue a return result.ToString(); and the resulting SQL selects have varying numbers of columns specified thus causing an MSSQL Msg 205... using (var db = GetDb()) { var fundInv = from f in db.funds select new Investments { Company = f.company, FullName = f.fullname, Admin = f.admin, Fund = f.fund1, FundCode = f.fundcode, Source = STR_FUNDS, IsPortfolio = false, IsActive = f.active, Strategy = f.strategy, SubStrategy = f.substrategy, AltStrategy = f.altstrategy, AltSubStrategy = f.altsubstrategy, Region = f.region, AltRegion = f.altregion, UseAlternate = f.usealt, ClassesAllowed = f.classallowed }; var stocksInv = from s in db.stocks where !fundInv.Select(f => f.Company).Contains(s.vehcode) select new Investments { Company = s.company, FullName = s.issuer, Admin = STR_PRS, Fund = s.shortname, FundCode = s.vehcode, Source = STR_STOCK, IsPortfolio = false, IsActive = (s.inactive == null), Strategy = s.style, SubStrategy = s.substyle, AltStrategy = s.altstyle, AltSubStrategy = s.altsubsty, Region = s.geography, AltRegion = s.altgeo, UseAlternate = s.usealt, ClassesAllowed = STR_GENERIC }; var bondsInv = from oi in db.bonds where !fundInv.Select(f => f.Company).Contains(oi.vehcode) select new Investments { Company = string.Empty, FullName = oi.issue, Admin = STR_PRS1, Fund = oi.issue, FundCode = oi.vehcode, Source = STR_BONDS, IsPortfolio = false, IsActive = oi.closed, Strategy = STR_OTH, SubStrategy = STR_OTH, AltStrategy = STR_OTH, AltSubStrategy = STR_OTH, Region = STR_OTH, AltRegion = STR_OTH, UseAlternate = false, ClassesAllowed = STR_GENERIC }; return (fundInv.Concat(stocksInv).Concat(bondsInv)).ToList(); } The code above results in a complex select statement where each "table" above has different column count. (see SQL below) I've been trying a few things but no change yet. Ideas are welcome. SELECT [t6].[company] AS [Company], [t6].[fullname] AS [FullName], [t6].[admin] AS [Admin], [t6].[fund] AS [Fund], [t6].[fundcode] AS [FundCode], [t6].[value] AS [Source], [t6].[value2] AS [IsPortfolio], [t6].[active] AS [IsActive], [t6].[strategy] AS [Strategy], [t6].[substrategy] AS [SubStrategy], [t6].[altstrategy] AS [AltStrategy], [t6].[altsubstrategy] AS [AltSubStrategy], [t6].[region] AS [Region], [t6].[altregion] AS [AltRegion], [t6].[usealt] AS [UseAlternate], [t6].[classallowed] AS [ClassesAllowed] FROM ( SELECT [t3].[company], [t3].[fullname], [t3].[admin], [t3].[fund], [t3].[fundcode], [t3].[value], [t3].[value2], [t3].[active], [t3].[strategy], [t3].[substrategy], [t3].[altstrategy], [t3].[altsubstrategy], [t3].[region], [t3].[altregion], [t3].[usealt], [t3].[classallowed] FROM ( SELECT [t0].[company], [t0].[fullname], [t0].[admin], [t0].[fund], [t0].[fundcode], @p0 AS [value], [t0].[active], [t0].[strategy], [t0].[substrategy], [t0].[altstrategy], [t0].[altsubstrategy], [t0].[region], [t0].[altregion], [t0].[usealt], [t0].[classallowed] FROM [zInvest].[funds] AS [t0] UNION ALL SELECT [t1].[company], [t1].[issuer], @p6 AS [value], [t1].[shortname], [t1].[vehcode], @p7 AS [value2], @p8 AS [value3], (CASE WHEN [t1].[inactive] IS NULL THEN 1 ELSE 0 END) AS [value5], [t1].[style], [t1].[substyle], [t1].[altstyle], [t1].[altsubsty], [t1].[geography], [t1].[altgeo], [t1].[usealt], @p10 AS [value6] FROM [zBank].[stocks] AS [t1] WHERE (NOT (EXISTS( SELECT NULL AS [EMPTY] FROM [zInvest].[funds] AS [t2] WHERE [t2].[company] = [t1].[vehcode] ))) AND ([t1].[vehcode] <> @p2) AND (SUBSTRING([t1].[vehcode], @p3 + 1, @p4) <> @p5) ) AS [t3] UNION ALL SELECT @p11 AS [value], [t4].[issue], @p12 AS [value2], [t4].[vehcode], @p13 AS [value3], @p14 AS [value4], [t4].[closed], @p16 AS [value6], @p17 AS [value7] FROM [zMut].[bonds] AS [t4] WHERE NOT (EXISTS( SELECT NULL AS [EMPTY] FROM [zInvest].[funds] AS [t5] WHERE [t5].[company] = [t4].[vehcode] )) ) AS [t6]