Column name case changes from camel case to lowercase, when we import data to elastic from SQL DB

SQL DB Column names are Id , FirstName , LastName.
When we imported data to elastic Search , the column name are changes to id, firstname , lastname.

Is there any solution to keep column name as its?

You need to do that in the mapping of the fields, you can either set them to not_analyzed or create your own analysis chain without the lower case analyzer.

Thanks for your replay.
Can you please give me reference URLs.

How are you importing the data?

Mark's comment about field mapping applies to the value of the fields but not the name of the fields.

we are importing data using Nest.
We have created the C# utility to import data . we read data from SQL DB and import as object into elastic search

        Uri ESUrl = new Uri(URL);
        string IndexArry = "discussions,discussion";
        var settings = new ConnectionSettings(ESUrl);
        var client = new ElasticClient(settings);

        try
        {
            var request = new BulkDescriptor();
            string[] IndexType = IndexArry.Split(',');
            if (IndexType.Count() > 1)
            {
                foreach (sqlDBData item in contentItems)
                {
                    request.Index<sqlDBData>(op => op
                            .Index(IndexType[0])
                            .Type(IndexType[1])
                            .Id(item.Id)
                            .Document(item)
                            );

                }
                var result = client.Bulk(request);
            }
        catch (Exception e)
        {
            string m = e.Message;
            // can do this logging thing.
        }

we have used Nest.dll for import the data into elastic search in C#
Uri ESUrl = new Uri(URL);
string IndexArry = "discussions,discussion";
var settings = new ConnectionSettings(ESUrl);
var client = new ElasticClient(settings);

        try
        {
            var request = new BulkDescriptor();
            string[] IndexType = IndexArry.Split(',');
            if (IndexType.Count() > 1)
            {
                foreach (DiscussionDbDetails item in contentItems)
                {
                    request.Index<DiscussionDbDetails>(op => op
                            .Index(IndexType[0])
                            .Type(IndexType[1])
                            .Id(item.Id)
                            .Document(item)
                            );

                }
                var result = client.Bulk(request);
            }
        }
        catch (Exception e)
        {
            string m = e.Message;
            // can do this logging thing.
        }

I doubt the Nest client does the down-casing of the field names. Have you double-checked that the down-casing doesn't take place when DiscussionDbDetails objects are serialized to JSON?

I have cross check the Document in request which is pass to bulk insert , object is not down-casing.
var result = client.Bulk(request)
((Nest.BulkIndexDescriptor<ESConnecter.DiscussionDbDetails>)((new System.Collections.Generic.Mscorlib_CollectionDebugView<Nest.IBulkOperation>(((System.Collections.Generic.SynchronizedCollection<Nest.IBulkOperation>)(request.Nest.IBulkRequest.Operations)).items)).Items[0])).Nest.IIndexOperation.Document

That screenshot only proves that the original member names are mixed case. Anyway, this seems to be an issue with Nest after all: