Get multiple MAX values from single query across multiple columns using Linq

Question

I'm trying to select the max values of 3 columns from a table. All the fields being returned from the query are Strings.

What I have sofar

var step1 =  from result in t_hsbc_staging_trts_derived_tbl_ac_balance.AsQueryable()
             where result.branch_no == brnchnu
                && result.deal_id == dealid
                && result.group_mbr == grpmem
                && result.ac_type != "RMC"
             select result ;

var branch = from result in step1
             select new {ccbranch = result.cc_branch.Max()};
var sect = from result in step1
           select new { ccsect = result.cc_sect.Max()};
var dept = from result in step1
             select new { ccdept = result.cc_dept.Max()};

foreach (var result in branch)
{
  string cc_branch = result.ccbranch.ToString();
}

The error I'm getting at the foreach statement is:

Sequence operators not supported for type 'System.String'.

There must be an easier way to just get the max values from this table?

SWeko · Accepted Answer · 2013-09-18 10:14:19Z

2

You are calling the Max() function on result.cc_branch which is itself a string. Even if it was successful, it would return the character of the string that has the largest unicode number, i.e.

 string s = "one-two-three";
 Console.WriteLine(s.Max()); // returns 'w'

Since I assume that is not what you want, and that you want the largest branch / section / department value, you can use:

string branch = (from result in step1 select result.cc_branch).Max();
string sect = (from result in step1 select result.cc_sect).Max();
string dept = (from result in step1 select result.cc_dept).Max();

answered Sep 18, 2013 at 10:14

SWeko

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3 Comments

TalentTuner Over a year ago

How do you know result.cc_branch is string ? its no where mentioned.

SWeko Over a year ago

@Saurabh: It's mentioned in the question by the OP, and also the error is very suggestive.

Sergey Berezovskiy Over a year ago

With method syntax it will be even better step1.Max(r => r.cc_branch)

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