C++封装odbc连接sql server的增删查改

以下是用C++封装ODBC连接SQL Server的增删查改示例代码：

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

using namespace std;

class SQLServerConnection {
public:
    SQLServerConnection(string server, string database, string username, string password) {
        connHandle = NULL;
        SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &envHandle);
        SQLSetEnvAttr(envHandle, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, SQL_IS_INTEGER);
        SQLAllocHandle(SQL_HANDLE_DBC, envHandle, &connHandle);
        SQLDriverConnect(connHandle, NULL, (SQLCHAR*)("DRIVER={SQL Server};SERVER=" + server + ";DATABASE=" + database + ";UID=" + username + ";PWD=" + password + ";"), SQL_NTS, NULL, 0, NULL, SQL_DRIVER_COMPLETE);
    }

    ~SQLServerConnection() {
        SQLDisconnect(connHandle);
        SQLFreeHandle(SQL_HANDLE_DBC, connHandle);
        SQLFreeHandle(SQL_HANDLE_ENV, envHandle);
    }

    void execute(string query) {
        SQLAllocHandle(SQL_HANDLE_STMT, connHandle, &stmtHandle);
        SQLExecDirect(stmtHandle, (SQLCHAR*)query.c_str(), SQL_NTS);
        SQLFreeHandle(SQL_HANDLE_STMT, stmtHandle);
    }

    void insert(string table, string columns, string values) {
        string query = "INSERT INTO " + table + "(" + columns + ") VALUES(" + values + ")";
        execute(query);
    }

    void update(string table, string setColumn, string setValue, string whereColumn, string whereValue) {
        string query = "UPDATE " + table + " SET " + setColumn + "='" + setValue + "' WHERE " + whereColumn + "='" + whereValue + "'";
        execute(query);
    }

    void remove(string table, string whereColumn, string whereValue) {
        string query = "DELETE FROM " + table + " WHERE " + whereColumn + "='" + whereValue + "'";
        execute(query);
    }

    void select(string table, string columns = "*", string whereColumn = "", string whereValue = "") {
        string query = "SELECT " + columns + " FROM " + table;
        if (!whereColumn.empty()) {
            query += " WHERE " + whereColumn + "='" + whereValue + "'";
        }
        SQLAllocHandle(SQL_HANDLE_STMT, connHandle, &stmtHandle);
        SQLExecDirect(stmtHandle, (SQLCHAR*)query.c_str(), SQL_NTS);

        SQLCHAR column[256];
        SQLLEN indicator;
        int numCols = 0;
        SQLNumResultCols(stmtHandle, (SQLSMALLINT*)&numCols);
        while (SQLFetch(stmtHandle) == SQL_SUCCESS) {
            for (int i = 1; i <= numCols; i++) {
                SQLGetData(stmtHandle, i, SQL_C_CHAR, column, sizeof(column), &indicator);
                cout << (char*)column << " ";
            }
            cout << endl;
        }

        SQLFreeHandle(SQL_HANDLE_STMT, stmtHandle);
    }

private:
    SQLHANDLE envHandle;
    SQLHANDLE connHandle;
    SQLHANDLE stmtHandle;
};

int main() {
    string server = "localhost\\SQLEXPRESS";
    string database = "test";
    string username = "sa";
    string password = "password";

    SQLServerConnection conn(server, database, username, password);

    // 插入数据
    conn.insert("myTable", "name, age, gender", "'Tom', 20, 'M'");

    // 更新数据
    conn.update("myTable", "age", "25", "name", "Tom");

    // 删除数据
    conn.remove("myTable", "name", "Tom");

    // 查询数据
    conn.select("myTable");
    conn.select("myTable", "name, age");
    conn.select("myTable", "*", "gender", "M");

    return 0;
}

在上面的示例代码中，我们使用了ODBC API来连接SQL Server数据库，并封装了常见的增删查改操作。你可以根据自己的需要，修改代码以实现更复杂的功能。