Question

I am trying to create a CLR procedure to export SQL data to Excel that will contain more features than other options such as subtotals and highlighting.

This requires me to reference the Microsoft.Office.Interop.Excel dll, but I’m not sure how to actually include the assembly when I compile my code.

How can I include the Excel assembly in my CLR procedure?

using System;
using System.Collections.Generic;
using System.Text;
using System.Data.SqlClient;
using Excel = Microsoft.Office.Interop.Excel;
using System.Reflection;

public class ExportToExcel
{
[Microsoft.SqlServer.Server.SqlProcedure]
public static void ExportQueryResults(string queryText, string worksheetName, string fileName)
{
    using (SqlConnection cnn = new SqlConnection("context connection=true"))
    {
        //the temp list to hold the results in
        List<object[]> results = new List<object[]>();

        cnn.Open();
        //create the sql command
        SqlCommand cmd = new SqlCommand(queryText, cnn);
        using (SqlDataReader reader = cmd.ExecuteReader())
        {
            int fieldCount = reader.FieldCount;
            object[] headers = new object[fieldCount];
            for(int i = 0; i < fieldCount; i++)
            {
                headers[i] = reader.GetName(i);
            }

            //read the results
            while (reader.Read())
            {
                object[] values = new object[fieldCount];
                for (int i = 0; i < fieldCount; i++)
                {
                    values[i] = reader[i];
                }
                results.Add(values);
            }

            //convert the results into a 2-d array to export into Excel
            object[,] exportVals = new object[results.Count, fieldCount];

            for (int row = 0; row < results.Count; row++)
            {
                for (int col = 0; col < fieldCount; col++)
                {
                    exportVals[row, col] = results[row][col];
                }
            }

            Excel.Application _app = new Excel.Application();
            Excel.Workbook _book = _app.Workbooks.Add(Missing.Value);
            Excel.Worksheet _sheet = (Excel.Worksheet)_book.ActiveSheet;
            Excel.Range _range = (Excel.Range)_sheet.Cells[1, 1];

            _range = _sheet.get_Range(_sheet.Cells[1, 1], _sheet.Cells[results.Count, fieldCount]);
            _range.Value2 = exportVals;

            _sheet.Name = worksheetName;

            //remove any extra worksheets
            foreach(Excel.Worksheet sht in _book.Worksheets)
            {
                if (sht.Name != worksheetName)
                    sht.Delete();
            }

            _book.SaveAs(fileName
                , Excel.XlFileFormat.xlWorkbookDefault
                , Missing.Value
                , Missing.Value
                , false
                , false
                , Excel.XlSaveAsAccessMode.xlNoChange
                , Missing.Value
                , Missing.Value
                , Missing.Value
                , Missing.Value
                , Missing.Value);
        }
    }
}
}

Answer 1

After a day of fumbling around with nearly every type of error possible, I came up with a solution for my problems.

I appreciate the answers/comments given, and although I agree there may be more efficient / secure ways of implementing a solution, using the interop assembly was the fastest and most familiar to complete this project.

Before I get raked over the coals, please realize that auto-filtering and other formatting outside the scope of the more traditional SQL Server export functionality were absolutely required for this project.

Solution

I created a class library output type visual studio project titled SqlProcedures, created a new class called ExportToExcel and added Microsoft.Office.Interop.Excel to my references.

Here is the code in my ExportToExcel.cs file:

using System;
using System.Collections.Generic;
using System.Text;
using System.Data.SqlClient;
using Excel = Microsoft.Office.Interop.Excel;
using System.Reflection;
using System.Runtime.InteropServices;

public class ExportToExcel
{
    [Microsoft.SqlServer.Server.SqlProcedure]
public static void ExportQueryResults(string queryText, string worksheetName, string fileName)
{
    using (SqlConnection cnn = new SqlConnection("context connection=true"))
    {
        //the temp list to hold the results in
        List<object[]> results = new List<object[]>();

        cnn.Open();
        //create the sql command
        SqlCommand cmd = new SqlCommand(queryText, cnn);
        using (SqlDataReader reader = cmd.ExecuteReader())
        {
            int fieldCount = reader.FieldCount;
            object[] headers = new object[fieldCount];
            for (int i = 0; i < fieldCount; i++)
            {
                headers[i] = reader.GetName(i);
            }

            //read the results
            while (reader.Read())
            {
                object[] values = new object[fieldCount];
                for (int i = 0; i < fieldCount; i++)
                {
                    values[i] = reader[i];
                }
                results.Add(values);
            }

            //convert the results into a 2-d array to export into Excel
            object[,] exportVals = new object[results.Count, fieldCount];

            for (int row = 0; row < results.Count; row++)
            {
                for (int col = 0; col < fieldCount; col++)
                {
                    exportVals[row, col] = results[row][col];
                }
            }

            Excel.Application _app = new Excel.Application();
            Excel.Workbook _book = _app.Workbooks.Add(Missing.Value);
            Excel.Worksheet _sheet = (Excel.Worksheet)_book.ActiveSheet;
            Excel.Range _range = (Excel.Range)_sheet.Cells[1, 1];
            _app.DisplayAlerts = false;

            //set the headers and freeze the panes
            _range = _sheet.get_Range(_sheet.Cells[1, 1], _sheet.Cells[1, fieldCount]);
            _range.NumberFormat = "@";
            _range.HorizontalAlignment = Excel.XlHAlign.xlHAlignLeft;
            _range.Value2 = headers;
            _range.Font.Bold = true;
            _range = _sheet.get_Range(_sheet.Cells[2, 1], _sheet.Cells[2, 1]);
            _range.EntireRow.Select();
            _range.Application.ActiveWindow.FreezePanes = true;

            _range = _sheet.get_Range(_sheet.Cells[2, 1], _sheet.Cells[results.Count, fieldCount]);
            _range.Value2 = exportVals;

            _range = _sheet.get_Range(_sheet.Cells[1, 1], _sheet.Cells[exportVals.Length, fieldCount]);
            _range.AutoFilter(1, Type.Missing, Excel.XlAutoFilterOperator.xlAnd, Type.Missing, true);
            _sheet.Cells.Columns.AutoFit();
            _sheet.Range["A1"].Select();

            _sheet.Name = worksheetName;

            //remove any extra worksheets
            foreach (Excel.Worksheet sht in _book.Worksheets)
            {
                if (sht.Name != worksheetName)
                    sht.Delete();
            }

            _book.SaveAs(fileName
                , Excel.XlFileFormat.xlExcel5
                , Missing.Value
                , Missing.Value
                , false
                , false
                , Excel.XlSaveAsAccessMode.xlNoChange
                , Missing.Value
                , Missing.Value
                , Missing.Value
                , Missing.Value
                , Missing.Value);

            //_book.Close(Missing.Value, Missing.Value, Missing.Value);
            _app.Application.Quit();

            GC.Collect();
            GC.WaitForPendingFinalizers();

            Marshal.ReleaseComObject(_range);
            Marshal.ReleaseComObject(_sheet);
            Marshal.ReleaseComObject(_book);
            Marshal.ReleaseComObject(_app);

            _range = null;
            _sheet = null;
            _book = null;
            _app = null;
            GC.Collect();
            GC.WaitForPendingFinalizers();
        }
    }
}
}

After sucessfully building the DLL, I copied it to a local directory on my SQL server.

In order to run the procedure ExportQueryResults, I needed to add several assemblies in the SQL server that the Microsoft.Office.Interop.Excel.dll depends on.

Here is my SQL code:

ALTER DATABASE main SET TRUSTWORTHY ON;

create assembly [stdole] from
'C:\Program Files\Microsoft.NET\Primary Interop Assemblies\stdole.dll'
WITH PERMISSION_SET = unsafe
create assembly [Office] from
'C:\WINDOWS\assembly\GAC\office\12.0.0.0__71e9bce111e9429c\OFFICE.DLL'
WITH PERMISSION_SET = unsafe

create assembly [Vbe] 
    FROM 'C:\WINDOWS\assembly\GAC\Microsoft.Vbe.Interop\12.0.0.0__71e9bce111e9429c\Microsoft.Vbe.Interop.dll'
WITH PERMISSION_SET = unsafe


create assembly [Microsoft.Office.Interop.Excel.dll] 
from 'C:\WINDOWS\assembly\GAC\Microsoft.Office.Interop.Excel\12.0.0.0__71e9bce111e9429c\Microsoft.Office.Interop.Excel.dll'
WITH PERMISSION_SET = unsafe

create assembly SqlProcedures from 'c:\sql_data_reporting\SqlProcedures.dll'
WITH PERMISSION_SET = unsafe
go
create procedure ExportToExcel @queryText nvarchar(4000), @worksheetName nvarchar(32),     @fileName nvarchar(250)
as external name SqlProcedures.ExportToExcel.ExportQueryResults
go

Now I know that using with permission_set = unsafe is a nono, but this was a “get it done now” project, and this was the fastest solution I could come up with.

Hopefully this solution will save some time for others who need to implement similar functionality.