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Support for Large UDTs

This sample solution contains two projects. One project creates an assembly (DLL) from C# source code. This assembly contains the CLR type. A table will be added to the database. A column in the table will be of a type defined in the assembly, By default, this sample will use the master database. The second project is a native C application that reads data from the table.

This sample will not work with any version of SQL Server earlier than SQL Server 2008.

For more information about support for large UDTs, see Large CLR User-Defined Types (ODBC).

The first code listing is C# source code. Paste it into a file called LargeStringUDT.cs and compile it to a DLL. Copy LargeStringUDT.dll to the root directory of your C drive.

The second (Transact-SQL) code listing creates the assembly in the master database.

Compile the second (C++) code listing with odbc32.lib and user32.lib. Make sure your INCLUDE environment variable includes the directory that contains sqlncli.h.

If you will build and run this sample as a 32-bit application on a 64-bit operating system, you must create the ODBC data source with the ODBC Administrator in %windir%\SysWOW64\odbcad32.exe.

This sample connects to your computer's default SQL Server instance. To connect to a named instance, change the definition of the ODBC data source to specify the instance using the following format: server\namedinstance. By default, SQL Server Express installs to a named instance.

The fourth (Transact-SQL) code listing deletes the assembly from the master database.

// LargeStringUDT.cs
// compile with: /target:library
using System;
using System.Data;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
using System.Text;

[assembly: System.CLSCompliantAttribute(true)]
[Serializable]
[Microsoft.SqlServer.Server.SqlUserDefinedType(Format.UserDefined, IsFixedLength = false, MaxByteSize = -1, IsByteOrdered = true)]
public class LargeStringUDT : INullable, IBinarySerialize {
    private bool _isNull;
    private string _largeString;

    public bool IsNull {
        get {
            return (_isNull);
        }
    }

    public static LargeStringUDT Null {
        get {
            LargeStringUDT lsUDT = new LargeStringUDT();
            lsUDT._isNull = true;
            return lsUDT;
        }
    }

    public override string ToString() {
        if (IsNull)
            return "NULL";
        else
            return _largeString;
    }

    [SqlMethod(OnNullCall = false)]
    public static LargeStringUDT Parse(SqlString s) {
        if (s.IsNull)
            return Null;

        LargeStringUDT lsUDT = new LargeStringUDT();
        lsUDT._largeString = s.Value;
        return lsUDT;
    }

    public String LargeString {
        get {
            return _largeString;
        }

        set {
            _largeString = value;
        }
    }

    public void Read(System.IO.BinaryReader r) {
        _isNull = r.ReadBoolean();
        if (!_isNull)
            _largeString = new String(r.ReadChars(r.ReadInt32()));
    }

    public void Write(System.IO.BinaryWriter w) {
        w.Write(_isNull);
        if (!_isNull) {
            w.Write(_largeString.Length);
            for (int i = 0; i < _largeString.Length; ++i)
                w.Write(_largeString[i]);
        }
    }
}
USE [MASTER]
IF EXISTS (SELECT * FROM sys.objects WHERE name = 'LargeStringUDTs')
   DROP TABLE LargeStringUDTs
GO

IF EXISTS (SELECT * FROM sys.types WHERE name = 'LargeStringUDT')
   DROP TYPE dbo.LargeStringUDT
GO

IF EXISTS (SELECT * FROM sys.assemblies WHERE name = 'LargeStringUDT')
   DROP ASSEMBLY LargeStringUDT
GO

CREATE ASSEMBLY LargeStringUDT
FROM 'C:\LargeStringUDT.dll'
WITh PERMISSION_SET=SAFE;
GO

CREATE TYPE dbo.LargeStringUDT 
EXTERNAL NAME LargeStringUDT.[LargeStringUDT];
GO

CREATE TABLE dbo.LargeStringUDTs
(ID int IDENTITY(1,1) PRIMARY KEY, LargeString LargeStringUDT)
GO

INSERT INTO dbo.LargeStringUDTs (LargeString) VALUES (CONVERT(LargeStringUDT, 'This is the first string'));
INSERT INTO dbo.LargeStringUDTs (LargeString) VALUES (CONVERT(LargeStringUDT, 'This is the second string'));
INSERT INTO dbo.LargeStringUDTs (LargeString) VALUES (Convert(LargeStringUDT, 'This is the third string'));
GO
// compile with: odbc32.lib
#include <stdio.h>
#include <tchar.h>
#include <stddef.h>
#include <windows.h>
#define ODBCVER 0x0350
#include <sql.h>
#include <sqlext.h>
#include <sqltypes.h>
#define _SQLNCLI_ODBC
#include "sqlncli.h"

int main() {
   // The command to execute.
   SQLTCHAR* szCmdString = (SQLTCHAR *)_T("SELECT ID, LargeString FROM dbo.LargeStringUDTs");

   int ret = 0;
   SQLRETURN rc;
   SQLHENV hEnv = NULL;
   SQLHDBC hDbc = NULL;
   SQLHSTMT hStmt = NULL;
   SQLTCHAR szConn[256]; 
   BYTE DataBuf[15];
   SQLSMALLINT iLen = 0;
   SQLLEN iDataLen = 0;

   rc = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &hEnv);
   if (rc != SQL_SUCCESS) {
      printf("Failed to get HENV\n");
      return -1;
   }

   rc = SQLSetEnvAttr (hEnv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, 0);
   if (rc != SQL_SUCCESS) {
      printf("Failed to SetEnvAttr\n");
      SQLFreeHandle(SQL_HANDLE_ENV, hEnv);
      return -1;
   }

   rc = SQLAllocHandle(SQL_HANDLE_DBC, hEnv, &hDbc);
   if (rc != SQL_SUCCESS) {
      printf("Failed to get HDBC\n");
      SQLFreeHandle(SQL_HANDLE_ENV, hEnv);
      return -1;
   }

   rc = SQLDriverConnect(hDbc, NULL, 
      (SQLTCHAR *)_T("DRIVER={SQL Server Native Client 10.0};SERVER=(local);Trusted_Connection=Yes;database=master"), 
      SQL_NTS, szConn, 255, &iLen, SQL_DRIVER_NOPROMPT);
   if (rc != SQL_SUCCESS && rc != SQL_SUCCESS_WITH_INFO) {
      printf("Failed to connect\n");
      ret = -1;
      goto End;
   }

   rc = SQLAllocHandle(SQL_HANDLE_STMT, hDbc, &hStmt);
   if (rc != SQL_SUCCESS) {
      printf("Failed to get hstmt\n");
      ret = -1;
      goto End;
   }

   // Execute the command.
   rc = SQLExecDirect(hStmt, szCmdString, SQL_NTS);
   if (rc != SQL_SUCCESS) {
      printf("Failed to get hstmt\n");
      ret = -1;
      goto End;
   }

   // Process the result set.
   SQLSMALLINT paramType;
   SQLTCHAR szData[100], szData2[100];
   SQLSMALLINT NameLengthPtr = 0, DataTypePtr, DecimalDigitsPtr, NullablePtr;
   SQLULEN ColumnSizePtr[2];
   rc = SQLDescribeCol(hStmt, 1, szData, sizeof(szData), &NameLengthPtr, &DataTypePtr, &ColumnSizePtr[0], &DecimalDigitsPtr, &NullablePtr);
   _tprintf(_T("%s"), szData);
   rc = SQLDescribeCol(hStmt, 2, szData2, sizeof(szData2), &NameLengthPtr, &DataTypePtr, &ColumnSizePtr[1], &DecimalDigitsPtr, &NullablePtr);
   _tprintf(_T("          %s\n"), szData2);

   while ( ( rc = SQLFetch(hStmt ) ) == SQL_SUCCESS ) {
      rc = SQLGetData(hStmt, 1, SQL_C_SHORT, &paramType, sizeof(SQL_C_SHORT), NULL);
      printf("%d           ", paramType);

      bool ifFirst = true;
      while ( ( rc = SQLGetData(hStmt, 2 , SQL_C_BINARY, DataBuf, sizeof(DataBuf) ,&iDataLen ) ) != SQL_NO_DATA) {
         // process number of bytes in the DataBuf;
         int NumBytes = (iDataLen > sizeof(DataBuf)) || (iDataLen == SQL_NO_TOTAL) ? sizeof(DataBuf): iDataLen;
         for ( int i = ifFirst?5:0 ; i <NumBytes ; i++ )
            putchar((char)DataBuf[i]);
         ifFirst = false;
      };
      printf("\n");
   }

   if ( rc != SQL_NO_DATA ) {
      printf("Failed to fetch data\n");
      ret= -1;
   }

End:
   if (hStmt) {
      SQLFreeStmt(hStmt,SQL_CLOSE);
      SQLFreeStmt(hStmt,SQL_DROP);
   }

   if (hDbc) {
      SQLDisconnect(hDbc);
      SQLFreeConnect(hDbc);
   }

   if (hEnv)
      SQLFreeHandle(SQL_HANDLE_ENV, hEnv);
};
USE [MASTER]
IF EXISTS (SELECT * FROM sys.objects WHERE name = 'LargeStringUDTs')
   DROP TABLE LargeStringUDTs
GO

IF EXISTS (SELECT * FROM sys.types WHERE name = 'LargeStringUDT')
   DROP TYPE dbo.LargeStringUDT
GO

IF EXISTS (SELECT * FROM sys.assemblies WHERE name = 'LargeStringUDT')
   DROP ASSEMBLY LargeStringUDT
GO
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