C++/CLI Code Snippet - Check Record Exists in SQL Server Database

C++/CLI Code Snippet - Check Record Exists in SQL Server Database

This .Net C++/CLI code snippet connects to SQL server and executes SQL statement to determine whether the given record exists in the database. To use this function simply provide open database connection and SQL statement. This function uses SqlClient name space to execute sql statement and return logical (True/False) result to check record exists or not in the database. Modify the exception handling section for your project requirements.

bool RecordExists(System::Data::SqlClient::SqlConnection ^%_SqlConnection, System::String ^_SQL)
{
    System::Data::SqlClient::SqlDataReader ^_SqlDataReader = nullptr;

    try
    {
        // Pass the connection to a command object
        System::Data::SqlClient::SqlCommand ^_SqlCommand = gcnew System::Data::SqlClient::SqlCommand(_SQL, _SqlConnection);

        // get query results
        _SqlDataReader = _SqlCommand->ExecuteReader();

    }
    catch (Exception ^_Exception)
    {
        // Error occurred while trying to execute reader
        // send error message to console (change below line to customize error handling)
        Console::WriteLine(_Exception->Message);

        return false;
    }

    if (_SqlDataReader != nullptr && _SqlDataReader->Read())
    {
        // close sql reader before exit
        if (_SqlDataReader != nullptr)
        {
            _SqlDataReader->Close();
            delete _SqlDataReader;
        }

        // record found
        return true;
    }
    else
    {
        // close sql reader before exit
        if (_SqlDataReader != nullptr)
        {
            _SqlDataReader->Close();
            delete _SqlDataReader;
        }

        // record not found
        return false;
    }
}

Here is a simple example showing how to use above function (RecordExists) to login to SQL server and check whether the record exists in the database.

// set temporary variable for database connection
System::Data::SqlClient::SqlConnection ^_SqlConnection = gcnew System::Data::SqlClient::SqlConnection();

// assign database connection string
_SqlConnection->ConnectionString = "Server=SERVERADDRESS;Database=DATABASENAME;Uid=USERID;Pwd=PASSWORD;";

// Connect to database
try
{
    _SqlConnection->Open();
}
catch (Exception ^_Exception)
{
    // Error occurred while trying to connect to database
    Console::WriteLine(_Exception->Message);
}

// Check for valid open database connection before query database
if (_SqlConnection != nullptr && _SqlConnection->State == ConnectionState::Open)
{
    if (RecordExists(_SqlConnection, "SELECT name FROM sampletable WHERE productid = 2"))
    {
        // record found in DB, lets do record found task
        Console::WriteLine("Record exists");
    }
    else
    {
        // record not found in DB, lets do record not found task
        Console::WriteLine("Record not found");
    }

    // close database connection
    _SqlConnection->Close();
}

C++/CLI Keywords Used:

• SqlDataReader
• SqlConnection
• ConnectionString
• SqlCommand
• ExecuteReader
• Exception

Code Snippet Information:

• Applies To: .Net, C++, CLI, SQL, Record Exists, SQL Server, SQL Client, Connection String, Database Connection, SQL Data Reader
• Programming Language : C++/CLI

External Resources:

• SqlDataReader Class
• SqlConnection Class
• SqlConnection.ConnectionString Property
• SqlCommand Class
• SqlCommand.ExecuteReader Method
• Exception Class

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