c语言连接sqlserver数据库

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

void checkSqlError(SQLRETURN ret, SQLSMALLINT handleType, SQLHANDLE handle, const char* msg) {
    if (ret != SQL_SUCCESS) {
        SQLCHAR sqlState[6], sqlMessage[SQL_MAX_MESSAGE_LENGTH];
        SQLSMALLINT i;
        SQLINTEGER nativeError;
        SQLSMALLINT textLength;
        SQLGetDiagRec(handleType, handle, 1, sqlState, &nativeError, sqlMessage, sizeof(sqlMessage), &textLength);
        fprintf(stderr, "%s: SQLSTATE=%s, NativeError=%d, Message=%s\n", msg, sqlState, nativeError, sqlMessage);
    }
}

int main() {
    SQLHENV env;
    SQLHDBC dbc;
    SQLHSTMT stmt;
    SQLRETURN ret;

    // Allocate environment handle
    ret = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &env);
    checkSqlError(ret, SQL_HANDLE_ENV, env, "Failed to allocate environment handle");

    // Set the ODBC version environment attribute
    ret = SQLSetEnvAttr(env, SQL_ATTR_ODBC_VERSION, (void*)SQL_OV_ODBC3, 0);
    checkSqlError(ret, SQL_HANDLE_ENV, env, "Failed to set ODBC version");

    // Allocate connection handle
    ret = SQLAllocHandle(SQL_HANDLE_DBC, env, &dbc);
    checkSqlError(ret, SQL_HANDLE_DBC, dbc, "Failed to allocate connection handle");

    // Connect to the database
    ret = SQLConnect(dbc, (SQLCHAR*)"YourServerName", SQL_NTS, (SQLCHAR*)"YourUsername", SQL_NTS, (SQLCHAR*)"YourPassword", SQL_NTS);
    checkSqlError(ret, SQL_HANDLE_DBC, dbc, "Failed to connect to the database");

    if (ret == SQL_SUCCESS) {
        printf("Connected to the database successfully!\n");

        // Allocate statement handle
        ret = SQLAllocHandle(SQL_HANDLE_STMT, dbc, &stmt);
        checkSqlError(ret, SQL_HANDLE_STMT, stmt, "Failed to allocate statement handle");

        // Execute a query
        ret = SQLExecDirect(stmt, (SQLCHAR*)"SELECT * FROM YourTableName", SQL_NTS);
        checkSqlError(ret, SQL_HANDLE_STMT, stmt, "Failed to execute query");

        if (ret == SQL_SUCCESS) {
            SQLCHAR columnValue[256];
            while (SQLFetch(stmt) == SQL_SUCCESS) {
                SQLGetData(stmt, 1, SQL_C_CHAR, columnValue, sizeof(columnValue), NULL);
                printf("Column Value: %s\n", columnValue);
            }
        }

        // Free statement handle
        SQLFreeHandle(SQL_HANDLE_STMT, stmt);
    }

    // Disconnect and free connection handle
    SQLDisconnect(dbc);
    SQLFreeHandle(SQL_HANDLE_DBC, dbc);

    // Free environment handle
    SQLFreeHandle(SQL_HANDLE_ENV, env);

    return 0;
}