C++利用Ｓｑｌｉｔｅ3实现增删改查等功能

使用SQLite3实现增删改查等功能需要先安装SQLite3的库文件和头文件，然后在C++代码中调用SQLite3提供的API来实现相应的功能。

以下是一个简单的示例，演示如何使用SQLite3在C++中实现增删改查等功能：

#include <iostream>
#include <sqlite3.h>

int main()
{
    sqlite3 *db;
    char *zErrMsg = 0;
    int rc;

    rc = sqlite3_open("test.db", &db);

    if (rc) {
        std::cerr << "Can't open database: " << sqlite3_errmsg(db) << std::endl;
        return 1;
    } else {
        std::cout << "Opened database successfully" << std::endl;
    }

    // 创建表
    const char *sql_create_table = "CREATE TABLE COMPANY("
                                   "ID INT PRIMARY KEY     NOT NULL,"
                                   "NAME           TEXT    NOT NULL,"
                                   "AGE            INT     NOT NULL,"
                                   "ADDRESS        CHAR(50),"
                                   "SALARY         REAL );";
    rc = sqlite3_exec(db, sql_create_table, 0, 0, &zErrMsg);
    if (rc != SQLITE_OK) {
        std::cerr << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    } else {
        std::cout << "Table created successfully" << std::endl;
    }

    // 插入数据
    const char *sql_insert = "INSERT INTO COMPANY(ID,NAME,AGE,ADDRESS,SALARY) "
                             "VALUES (1, 'Paul', 32, 'California', 20000.00 ); "
                             "INSERT INTO COMPANY(ID,NAME,AGE,ADDRESS,SALARY) "
                             "VALUES (2, 'Allen', 25, 'Texas', 15000.00 ); "
                             "INSERT INTO COMPANY(ID,NAME,AGE,ADDRESS,SALARY)"
                             "VALUES (3, 'Teddy', 23, 'Norway', 20000.00 );"
                             "INSERT INTO COMPANY(ID,NAME,AGE,ADDRESS,SALARY)"
                             "VALUES (4, 'Mark', 25, 'Rich-Mond', 65000.00 );";
    rc = sqlite3_exec(db, sql_insert, 0, 0, &zErrMsg);
    if (rc != SQLITE_OK) {
        std::cerr << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    } else {
        std::cout << "Records created successfully" << std::endl;
    }

    // 查询数据
    const char *sql_select = "SELECT * from COMPANY";
    sqlite3_stmt *stmt;
    rc = sqlite3_prepare_v2(db, sql_select, -1, &stmt, nullptr);
    if (rc == SQLITE_OK) {
        while (sqlite3_step(stmt) == SQLITE_ROW) {
            int id = sqlite3_column_int(stmt, 0);
            const unsigned char *name = sqlite3_column_text(stmt, 1);
            int age = sqlite3_column_int(stmt, 2);
            const unsigned char *address = sqlite3_column_text(stmt, 3);
            double salary = sqlite3_column_double(stmt, 4);

            std::cout << "ID = " << id << ", NAME = " << name << ", AGE = " << age <<
                      ", ADDRESS = " << address << ", SALARY = " << salary << std::endl;
        }
        sqlite3_finalize(stmt);
    } else {
        std::cerr << "SQL error: " << sqlite3_errmsg(db) << std::endl;
    }

    // 更新数据
    const char *sql_update = "UPDATE COMPANY set SALARY = 25000.00 where ID=1;";
    rc = sqlite3_exec(db, sql_update, 0, 0, &zErrMsg);
    if (rc != SQLITE_OK) {
        std::cerr << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    } else {
        std::cout << "Records updated successfully" << std::endl;
    }

    // 删除数据
    const char *sql_delete = "DELETE from COMPANY where ID=2;";
    rc = sqlite3_exec(db, sql_delete, 0, 0, &zErrMsg);
    if (rc != SQLITE_OK) {
        std::cerr << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    } else {
        std::cout << "Records deleted successfully" << std::endl;
    }

    sqlite3_close(db);

    return 0;
}

在这个示例中，我们首先打开一个名为“test.db”的数据库，然后创建了一个名为“COMPANY”的表，并向表中插入了一些数据。接着，我们查询了表中的数据，并尝试更新和删除数据。

当然，这只是一个简单的示例，实际使用中还需要根据具体需求进行更多的操作。但是这个示例应该足以帮助你理解如何使用SQLite3在C++中实现增删改查等功能。