Connect C ++ to the SQL database in steps

Each programming language has many methods for database operations when applied to program development. I have summarized a lot of online applications that use C ++ to connect to the SQL database without detailed instructions and complete solutions. In addition, due to my limited ability, the written content may have defects.

• C ++ Dynamic Object Creation Technology
• C ++ basic application guide for calling python script Functions
• Introduction to basic concepts of C-style strings in C ++
• Basic concepts of C ++ string types
• C ++ parameter transfer

Step 1: System Configuration

1. Set the SQLSERVER server to the SQL logon mode, and set the logon function to "enable" for the sa user in system security. A password is required.

2. you need to configure the data source in ODBC. Select \ "SQL server" as the data source, use "SQL SERVER verification with the user login ID and password entered" for logon, and enter the login name sa) and password. Note that the password cannot be blank, which means that your sa user must have a password. Otherwise, you cannot pass the security policy of the system. The configuration is completed after the test is passed.

C ++ connects to SQL database Step 2 C ++ and SQL connection Initialization

1. Introduce ADO in the stdafx. h header file of your C ++ project.

The Code is as follows:

 
 

  
  
#import “c:\Program Files\Common Files\System\ado\msado15.dll” 
no_namespace rename(”EOF”, “adoEOF”) rename(”BOF”, “adoBOF”) 
 
 

2. Define the _ ConnectionPtr variable and call the Open method of the Connection object to establish a Connection with the server.

The Data Type _ ConnectionPtr is actually a specific instance class obtained by the class template _ com_ptr_t. The _ ConnectionPtr class encapsulates the Idispatch interface pointer of the Connection object and some necessary operations. You can use this pointer to manipulate the Connection object.

For example, to connect to the SQLServer database, the Code is as follows:

 
 

  
  
// Connect to ms SQL Server
  
  
// Initialize the pointer
  
  
_ ConnectionPtr pMyConnect = NULL;
  
  
HRESULT hr = pMyConnect. CreateInstance (_ uuidof (Connection ));
  
  
If (FAILED (hr ))
  
  
Return;
  
  
// Initialize the link Parameters
  
  
_ Bstr_t strConnect = "Provider = SQLOLEDB;
  
  
Server = hch;
  
  
Database = mytest;
  
  
Uid = sa; pwd = sa; "; // Database indicates the Database in your system
  
  
// Execute the connection
  
  
Try
  
  
{
  
  
// The Open method connection string must be of the BSTR or _ bstr_t type.
  
  
PMyConnect-> Open (strConnect, "", "", NULL );
  
  
}
  
  
Catch (_ com_error & e)
  
  
{
  
  
MessageBox (e. Description (), "warning", MB_ OK | MB_ICONINFORMATION );
  
  
} // Link Error
 
 

C ++ connects to the SQL database step 3 simple data connection

 
 

  
  
// Define the _ RecordsetPtr variable and call the Recordset object Open to Open a dataset.
  
  
// The initialization process is as follows:
  
  
_ RecordsetPtr pRecordset;
  
  
If (FAILED (pRecordset. CreateInstance (_ uuidof (Recordset ))))
  
  
{
  
  
Return;
  
  
}
  
  
// Perform the operation
  
  
Try
  
  
{
  
  
PRecordset-> Open (_ variant_t ("userinfo "),
_ Variant_t (IDispatch *) pMyConnect ),
  
  
AdOpenKeyset, adLockOptimistic, adCmdTable );
  
  
}
  
  
Catch (_ com_error & e)
  
  
{
  
  
MessageBox ("Unable to open userinfo table \", "System prompt ",
MB_ OK | MB_ICONINFORMATION );
  
  
}
 
 

Step 4 of connecting C ++ to the SQL database

Here is the key. I think that as long as you know SQL statements, everything will be easier and more efficient than the above methods.

First

 
 

  
  
M_pConnection.CreateInstance (_ uuidof (Connection ));
// Initialize the Connection pointer
  
  
M_pRecordset.CreateInstance (_ uuidof (Recordset ));
// Initialize the Recordset pointer
  
  
CString strSql = "select * from tb_goods"; // The SQL statement to be executed
  
  
M_pRecordset = m_pConnection-> Execute (_ bstr_t (strSql ),
NULL, adCmdText); // import the query data to the m_pRecordset data container
 
 

Now that your SQL statement has been executed, the data in m_pRecordset is the result of your execution.

Retrieve records:

 
 

  
  
While (! M_pRecordset-> adoEOF) // traverses and reads records in the name column and outputs
  
  
{
  
  
CString temp = (TCHAR *) (_ bstr_t) m_pRecordset-> GetFields ()-> GetItem
  
  
("Name")-> Value;
  
  
AfxMessageBox (temp );
  
  
PRecordset-> MoveNext ();
  
  
}
 
 

Insert record

 
 

  
  
// Remember to initialize the pointer and then perform the following operations
  
  
CString strsql;
  
  
Strsql. Format ("insert into tb_goods (no, name, price)
Values ('% d',' % s', % d) ", m_intNo, m_strName, m_intPrice );
  
  
M_pRecordset = m_pConnection->
Execute (_ bstr_t (strsql), NULL, ad1_text );
 
 

Modify record

 
 

  
  
CString strsql;  
  
  
strsql.Format(”update tb_goods set name=’%s’ , 
price=%d where no=%d “,m_strName,m_intPrice,m_intNo);   
  
  
m_pRecordset=m_pConnection->Execute(_bstr_t(strsql),NULL,adCmdText); 
 
 

Delete record

 
 

  
  
CString strsql;  
  
  
strsql.Format(”delete from tb_goodswhere no= ‘%d’ “,m_intNo);  
  
  
m_pRecordset=m_pConnection->Execute(_bstr_t(strsql),NULL,adCmdText); 
 
 

These are several common SQL statements and execution methods. Efficiency may not be high, but it is easy to understand. If you are familiar with SQL statements, you can execute queries more effectively and directly obtain the required records. This section describes how to connect C ++ to the SQL database.