How to Connect C++ to SQL Database using ODBC | C / C++ ODBC app accessing an SQL database

In this article we are going to know about how to  establish a connection between C++ and an SQL database, you’ll need to use a library that provides the necessary functions and classes for connecting to and interacting with the database. One popular library for this purpose is called “ODBC” (Open Database Connectivity). ODBC allows you to connect to various database systems, including SQL-based databases like MySQL, PostgreSQL, and Microsoft SQL Server.

Here’s a step-by-step guide on how to establish a C++ connection to an SQL database using ODBC:

• Install the ODBC driver for your specific database system. The installation process may vary depending on the database you’re using. Consult the documentation for your database for instructions on how to install the ODBC driver.
• Include the necessary headers in your C++ program. To use ODBC, you’ll need to include the <sql.h> and <sqlext.h> headers. These headers contain the necessary definitions and functions for working with ODBC.

#include <sql.h>
#include <sqlext.h>

• Declare the necessary variables. You’ll need a handle for the connection (SQLHDBC), a handle for the environment (SQLHENV), and a return code variable (SQLRETURN) to store the results of function calls.

SQLHENV henv;   // Environment handle
SQLHDBC hdbc;   // Connection handle
SQLRETURN ret;  // Return code

• Initialize the environment and allocate a handle for the environment.

ret = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
ret = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, SQL_IS_INTEGER);

Allocate a handle for the connection.

ret = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);

• Connect to the database.

SQLCHAR* dsn = (SQLCHAR*)"your_dsn_name"; // Data Source Name (DSN)
SQLCHAR* user = (SQLCHAR*)"your_username";
SQLCHAR* pass = (SQLCHAR*)"your_password";

ret = SQLConnect(hdbc, dsn, SQL_NTS, user, SQL_NTS, pass, SQL_NTS);

Replace “your_dsn_name”, “your_username”, and “your_password” with the actual values for your database. 

if (ret == SQL_SUCCESS || ret == SQL_SUCCESS_WITH_INFO) {
    // Connection successful
} else {
    // Connection failed
}

ret = SQLDisconnect(hdbc);
ret = SQLFreeHandle(SQL_HANDLE_DBC, hdbc);
ret = SQLFreeHandle(SQL_HANDLE_ENV, henv);

Note: