Question

I have several functions in an assembly dll named UserFunctions.dll, for example :

public static partial class VariousFunctions
{
    [SqlFunction(IsDeterministic = true, IsPrecise = true)]
    public static SqlBoolean RegexMatch(SqlString expression, SqlString pattern)
    {
      ...
    }

    [SqlFunction(IsDeterministic = true, IsPrecise = true)]
    public static SqlInt32 WorkingDays(SqlDateTime startDateTime, SqlDateTime endDateTime)
    {
      ...
    }

    [SqlFunction(IsDeterministic = true, IsPrecise = true)]
    public static SqlString getVersion()
    {
      ...
    }

    ...
}

And I want to generate the sql script with a c# function, to create or update automatically all functions with attribute SqlFunction contained in this dll.
This sql script should look like this :

-- Delete all functions from assembly 'UserFunctions'
DECLARE @sql NVARCHAR(MAX)
SET @sql = 'DROP FUNCTION ' + STUFF(
            (
                SELECT
                    ', ' + QUOTENAME(assembly_method) 
                FROM
                    sys.assembly_modules
                WHERE
                    assembly_id IN (SELECT assembly_id FROM sys.assemblies WHERE name = 'UserFunctions')
                FOR XML PATH('')
            ), 1, 1, '')
-- SELECT @sql
IF @sql IS NOT NULL EXEC sp_executesql @sql


-- Create all functions from assembly 'UserFunctions'
CREATE FUNCTION RegexMatch(@expression NVARCHAR(MAX), @pattern NVARCHAR(MAX)) RETURNS BIT 
    AS EXTERNAL NAME UserFunctions.VariousFunctions.RegexMatch;
GO
CREATE FUNCTION WorkingDays(@startDateTime DATETIME, @endDateTime DATETIME) RETURNS INTEGER 
    AS EXTERNAL NAME UserFunctions.VariousFunctions.WorkingDays;
GO  
 CREATE FUNCTION getVersion() RETURNS VARCHAR(MAX) 
    AS EXTERNAL NAME UserFunctions.VariousFunctions.getVersion;
GO

The first part is very simple, but for the second part this is probably possible using the reflection methods of the classes Type, MethodInfo and ParameterInfo.
Someone has already done this ?

Answer 1

I have tested and debugged it :

static void Main(string[] args)
{
  Assembly clrAssembly = Assembly.LoadFrom(@"Path\to\your\assembly.dll");
  string sql = CreateFunctionsFromAssembly(clrAssembly, permissionSetType.UNSAFE);
  File.WriteAllText(sqlFile, sql);
}


/// <summary>
/// permissions available for an assembly dll in sql server
/// </summary>
public enum permissionSetType { SAFE, EXTERNAL_ACCESS, UNSAFE };


/// <summary>
/// generate sql from an assembly dll with all functions with attribute SqlFunction
/// </summary>
/// <param name="clrAssembly">assembly object</param>
/// <param name="permissionSet">sql server permission set</param>
/// <returns>sql script</returns>
public static string CreateFunctionsFromAssembly(Assembly clrAssembly, permissionSetType permissionSet)
{
    const string sqlTemplate = @"
      -- Delete all functions from assembly '{0}'
      DECLARE @sql NVARCHAR(MAX)
      SET @sql = 'DROP FUNCTION ' + STUFF(
        (
            SELECT
                ', ' + assembly_method 
            FROM
                sys.assembly_modules
            WHERE
                assembly_id IN (SELECT assembly_id FROM sys.assemblies WHERE name = '{0}')
            FOR XML PATH('')
        ), 1, 1, '')
      IF @sql IS NOT NULL EXEC sp_executesql @sql
      GO

      -- Delete existing assembly '{0}' if necessary
      IF EXISTS(SELECT 1 FROM sys.assemblies WHERE name = '{0}')
        DROP ASSEMBLY {0};
      GO

      {1}
      GO

      -- Create all functions from assembly '{0}'
    ";
    string assemblyName = clrAssembly.GetName().Name;

    StringBuilder sql = new StringBuilder();
    sql.AppendFormat(sqlTemplate, assemblyName, CreateSqlFromAssemblyDll(clrAssembly, permissionSet));

    foreach (Type classInfo in clrAssembly.GetTypes())
    {
        foreach (MethodInfo methodInfo in classInfo.GetMethods(BindingFlags.Static | BindingFlags.Public | BindingFlags.DeclaredOnly))
        {
            if (Attribute.IsDefined(methodInfo, typeof(SqlFunctionAttribute)))
            {
                StringBuilder methodParameters = new StringBuilder();
                bool firstParameter = true;
                foreach (ParameterInfo paramInfo in methodInfo.GetParameters())
                {
                    if (firstParameter)
                         firstParameter = false;
                    else
                        methodParameters.Append(", ");
                    methodParameters.AppendFormat(@"@{0} {1}", paramInfo.Name, ConvertClrTypeToSql(paramInfo.ParameterType));
                }
                string returnType = ConvertClrTypeToSql(methodInfo.ReturnParameter.ParameterType);
                string methodName = methodInfo.Name;
                string className = (classInfo.Namespace == null ? "" : classInfo.Namespace + ".") + classInfo.Name;
                string externalName = string.Format(@"{0}.[{1}].{2}", assemblyName, className, methodName);
                sql.AppendFormat(@"CREATE FUNCTION {0}({1}) RETURNS {2} AS EXTERNAL NAME {3};"
                                , methodName, methodParameters, returnType, externalName)
                   .Append("\nGO\n");
            }
        }
    }
    return sql.ToString();
}


/// <summary>
/// Generate sql script to create assembly
/// </summary>
/// <param name="clrAssembly"></param>
/// <param name="permissionSet">sql server permission set</param>
/// <returns></returns>
public static string CreateSqlFromAssemblyDll(Assembly clrAssembly, permissionSetType permissionSet)
{
    const string sqlTemplate = @"
      -- Create assembly '{0}' from dll
      CREATE ASSEMBLY [{0}] 
        AUTHORIZATION [dbo]
        FROM 0x{2}
        WITH PERMISSION_SET = {1};
    ";

    StringBuilder bytes = new StringBuilder();
    using (FileStream dll = File.OpenRead(clrAssembly.Location))
    {
        int @byte;
        while ((@byte = dll.ReadByte()) >= 0)
            bytes.AppendFormat("{0:X2}", @byte);
    }
    string sql = String.Format(sqlTemplate, clrAssembly.GetName().Name, permissionSet, bytes);

    return sql;
}


/// <summary>
/// Convert clr type to sql type
/// </summary>
/// <param name="clrType">clr type</param>
/// <returns>sql type</returns>
private static string ConvertClrTypeToSql(Type clrType)
{
    switch (clrType.Name)
    {
        case "SqlString":
            return "NVARCHAR(MAX)";
        case "SqlDateTime":
            return "DATETIME";
        case "SqlInt16":
            return "SMALLINT";
        case "SqlInt32":
            return "INTEGER";
        case "SqlInt64":
            return "BIGINT";
        case "SqlBoolean":
            return "BIT";
        case "SqlMoney":
            return "MONEY";
        case "SqlSingle":
            return "REAL";
        case "SqlDouble":
            return "DOUBLE";
        case "SqlDecimal":
            return "DECIMAL(18,0)";
        case "SqlBinary":
            return "VARBINARY(MAX)";
        default:
            throw new ArgumentOutOfRangeException(clrType.Name + " is not a valid sql type.");
    }
}