SQL Server
(ODBC)

Connecting to a database

Transaction isolation levels

Working with Long or Lob(CLob, BLob) data

Returning output parameters

Cancelling queries

Connection, command, parameter and field options

Getting native SQL Server (ODBC) API

Getting native SQL Server (ODBC) connection related handles

Getting native SQL Server (ODBC) command related handles

Error handling

Special header files - Compile time

Connecting to a database

To connect to a database you should create a connection object and then connect it. A connection object is represented by SAConnection class:

SAConnection con;

Starting from version 3.3.1 SQLAPI++ Library uses OLE DB as default API when working with SQL Server. If you want to use ODBC, you should set "UseAPI" connection option before specifying SQL Server client or connecting to database:

con.setOption( "UseAPI" ) = "ODBC";

If the Library cann't find ODBC interface it throws an exception.

After the connection is created you need to connect it to SQL Server using SAConnection::Connect method

void Connect( const SAString &sDBString, const SAString &sUserID, const SAString &sPassword, SAClient_t eSAClient = SA_Client_NotSpecified );

with the following parameters:

sDBString.      A connection string like "[[<server_name>@][<database_name][;<driver_connection_option_list>]"

• <server_name> - connects to a specified server.  If it's ommitted SQLAPI++ tries to connect to default local server instance.
  
• <database_name> - connects to a database with the specified name. If it's ommitted SQLAPI++ tries to connect to default database.
• <driver_connection_option_list>  - SQL Server Native ODBC driver specific option list.
  

To connect to a named instance of SQL Server use <server name\instance name> instead of <server_name> (use double back slash at C++ constants, for example "MyServer\\SQLEXPRESS@pubs").

sUserID.    A string containing a user name to use when establishing the connection. If sUserID parameter is empty, SQLAPI++ Library requests a secure, or trusted, connection to SQL Server.

sPassword.    A string containing a password to use when establishing the connection.

eSAClient.    Optional. One of the following values from SAClient_t enum:

• SA_SQLServer_Client    SQLServer client.
• SA_Client_NotSpecified     Used by default if eSAClientparameter is omitted.  You can use this default value only if you have call SAConnection::setClient method with SA_SQLServer_Client constant before.

The SQLAPI++ Library requires SQLServer ODBC version 2000.x or SQL Server Native Client (ODBC API) version 2005 and higher.

For more details see How To - Connecting to databases, SAConnection object, SAConnection::Connect.

Transaction isolation levels

SQL-92 defines four isolation levels, all of which are supported by SQLAPI++:

• Read uncommitted (the lowest level where transactions are isolated just enough to ensure that physically corrupt data is not read)
• Read committed
• Repeatable read
• Serializable (the highest level, where transactions are completely isolated from one another)

SQLAPI++ maps different isolation levels on SQL Server (ODBC) in the following way:

SA_ReadUncommitted = SQL_TXN_READ_UNCOMMITTED
SA_ReadCommitted = SQL_TXN_READ_COMMITTED
SA_RepeatableRead = SQL_TXN_REPEATABLE_READ
SA_Serializable = SQL_TXN_SERIALIZABLE

For more details see SAConnection::setIsolationLevel.

Working with Long or Lob(CLob, BLob) data

SQLAPI++ supports four types for working with Long and Lob(CLob, BLob) data:

Name	C enum constant
image	SA_dtLongBinary
text	SA_dtLongChar
varbinary(max)	SA_dtBLob
[n]varchar(max)	SA_dtCLob

SQLAPI++ maps data types to ODBC constants. Actual mapping from constant to SQL type is ODBC driver specific. The table below shows how SQLAPI++ data types correspond with ODBC constants:

SA_dtLongBinary <= > SQL_LONGVARBINARY
SA_dtLongChar <= > SQL_LONGVARCHAR
SA_dtBLob = > SQL_VARBINARY
SA_dtCLob => SQL_VARCHAR

For more details see How To - Working with Long or Lob(CLob, BLob) data , How To - Binding input parameters.

Returning output parameters

SQL Server stored procedures can have integer return codes and output parameters. The return codes and output parameters are sent in the last packet from the server and are therefore not available to the application until all result sets from stored procedure (if any) are completely processed using SACommand::FetchNext method.

SQLAPI++ Library automatically creates SAParam object to represent procedure status return code or function return value. You can refer to this SAParam object using SQLAPI++ predefined name "RETURN_VALUE".

SQLAPI++ Library doesn't support output [n]varchar(max)/varbinary(max) parameters because they aren't supported by ODBC API.

For more details see SACommand::Execute, SACommand::FetchNext, SAParam object, How To - Returning Output Parameters.

Cancelling queries

Using SACommand::Cancel method you can cancel the following types of processing on a statement:

• A function running asynchronously on the statement.
  
• A function running on the statement on another thread.

SQLAPI++ calls SQLCancel function to cancel a query. To get more details see SQLCancel function description in SQLServer Native Client ODBC documentation.

For more details see SACommand::Cancel, SQL Server (ODBC) connection and command options.

Connection, command, parameter and field options

A server specific option can relate to a connection, command,  parameter or field. We recommend you specify each option in an appropriate object, although it is possible to specify them in the parental object as well. In that case the option affects all the child objects.

A connection related option must be specified in a  SAConnection object.

A command related option may be specified in either SAConnection object or SACommand object. If it is specified in SAConnection object it affects all the commands on that connection.

A parameter related option may be specified in SAConnection object, SACommand object or SAParam object. If it is specified in SAConnection object it affects all the commands and therefore all the parameters on that connection. If it is specified in SACommand object it affects all the parameters on that command.

A field related option may be specified in SAConnection object, SACommand object or SAField object. If it is specified in SAConnection object it affects all the commands and therefore all the fields on that connection. If it is specified in SACommand object it affects all the fields on that command.

Specific options for SQL Server (ODBC):

Option name / Scope	Description
UseAPI Connection related. Should be specified before connection is made.	Forces SQLAPI++ Library to use OLE DB, ODBC or DB-Library API.   Valid values : "OLEDB", "ODBC" and "DB-Lib". Default value: "OLEDB". SQLAPI++ uses OLE DB as the default API.
SQLNCLI.LIBS Connection related. Should be specified before the first connection is made.	Specifies SQL Server Native client library list. SQLAPI++ tries to load libraries from this list one by one for loading SQL Server Natvie API. Valid values : shared library names separated by ';'. Default value: "sqlncli10.dll;sqlncli.dll;sqlsrv32.dll".
PreFetchRows Command related. Should be specified before command execution.	Forces SQLAPI++ Library to fetch rows in bulk, rather than retrieving records one by one. Valid values: String containing number of rows in the fetch buffer. Default value: "1".
UseDynamicCursor or Scrollable Command related.	Forces SQLAPI++ to use scrollable dynamic server side cursor. Valid values: "True", "1". Default value: "false".

For more details see SAConnection::setOption, SACommand::setOption, SAField::setOption, SAParam::setOption.

Getting native SQL Server (ODBC) API

You can call client specific API functions which are not directly supported by SQLAPI++ Library. SAConnection::NativeAPI method returns a pointer to the set of native API functions available for SQL Server (ODBC). To use the database API directly you have to downcast this saAPI pointer to the appropriate type and use its implementation-specific members. The following table shows what type cast you have to make and what additional header file you have to include to work with SQL Server with ODBC API. Note that using appropriate type casting depends on an API (that generally mean that you have to explicitly check client version before casting, see SAConnection::ClientVersion method).

Type casting	Additional include file
Cast the result to class ssNCliAPI: saAPI *pResult = con.NativeAPI(); ssAPI *p_ssAPI = (ssNCliAPI *)pResult;	#include <ssNcliAPI.h>

To get more information about DBMS API functions see this DBMS specific documentation. 

For more details see SAConnection::NativeAPI.

Getting native SQL Server (ODBC) connection related handles

You have to use native API handles when you want to call specific ODBC API functions which are not directly supported by the Library. API functions usually need to receive one or more active handles as a parameter(s). SAConnection::NativeHandles method returns a pointer to the set of native API connection related handles. To use API handles directly you have to downcast saConnectionHandles pointer to the appropriate type and use its implementation-specific members. The following table shows what type cast you have to make and what additional header file you have to include to work with SQL Server with ODBC API. Note that using appropriate type casting depends on an API (that generally mean that you have to explicitly check client version before casting, see SAConnection::ClientVersion method).

Type casting

Cast the result to class ssConnectionHandles: #include <ssNcliAPI.h> saConnectionHandles *pResult = con.NativeHandles(); ssNCliConnectionHandles *p_ssCH = (ssNCliConnectionHandles *)pResult; Available handles: SQLHENV m_hevn ; SQLHDBC m_hdbc ;

To get more information about DBMS API functions and handles see this DBMS specific documentation. 

For more details see SAConnection::NativeHandles.

Getting native SQL Server (ODBC) command related handles

You have to use native API handles when you want to call specific ODBC API functions which are not directly supported by the Library. API functions usually need to receive one or more active handles as a parameter(s). SACommand::NativeHandles method returns a pointer to the set of native API command related handles. To use API handles directly you have to downcast saCommandHandles pointer to the appropriate type and use its implementation-specific members. The following table shows what type cast you have to make and what additional header file you have to include to work with SQL Server with ODBC API. Note that using appropriate type casting depends on an API (that generally mean that you have to explicitly check client version before casting, see SAConnection::ClientVersion method).

Type casting

Cast the result to class ssCommandHandles: #include <ssNcliAPI.h> saCommandHandles *pResult = cmd.NativeHandles (); ssNCliCommandHandles *p_ssCH = (ssNCliCommandHandles *)pResult; Available handles: SQLHSTMT m_hstmt

To get more information about DBMS API functions and handles see this DBMS specific documentation. 

For more details see SACommand::NativeHandles.

Error handling

When an error occurs inside SQLAPI++ Library it throws an exception of type SAException. SAException::ErrPos method gets an error position in SQL statement. In SQL Server (ODBC) SAException::ErrPos method returns the number of the line within SQL statement where an error occured.

For more details see How To - Error handling, SAException object.

Special header files - Compile time

The header file in the include subdirectory of SQLAPI++ distributions:
#include <SQLAPI.h> - main header, should be used whenever SQLAPI++ is used.
#include <ssNcliAPI.h> - SQLServer API, should be included if direct ODBC calls are required.

For more details see Online Documentation - Instructions for Compiling and Linking Applications with SQLAPI++ 

Problems and Questions

If you haven't found the answer to you questions or have some problems on using the Library, please, send e-mail to howto@sqlapi.com.