C++使用sqlite3创建数据库，并实现增、删、查、改的代码

以下是使用C++语言和sqlite3库来创建数据库，并实现增、删、查、改的代码示例：

首先，需要包含sqlite3.h头文件和iostream头文件

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

接着，定义一个回调函数，用于处理查询结果：

static int callback(void *NotUsed, int argc, char **argv, char **azColName){
    int i;
    for(i=0; i<argc; i++){
        std::cout << azColName[i] << " = " << (argv[i] ? argv[i] : "NULL") << std::endl;
    }
    std::cout << std::endl;
    return 0;
}

然后，在主函数中创建或打开数据库，并执行增、删、查、改操作：

int main(int argc, char* argv[]){
    sqlite3* db;
    char* zErrMsg = 0;
    int rc;

    // 创建或打开数据库
    rc = sqlite3_open("test.db", &db);
    if( rc ){
        std::cerr << "Can't open database: " << sqlite3_errmsg(db) << std::endl;
        return 0;
    }else{
        std::cerr << "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, callback, 0, &zErrMsg);
    if( rc != SQLITE_OK ){
        std::cerr << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    }else{
        std::cerr << "Table created successfully" << std::endl;
    }

    // 插入数据
    const char* sql_insert_data = "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_data, callback, 0, &zErrMsg);
    if( rc != SQLITE_OK ){
        std::cerr << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    }else{
        std::cerr << "Records created successfully" << std::endl;
    }

    // 查询数据
    const char* sql_select_data = "SELECT * from COMPANY";
    rc = sqlite3_exec(db, sql_select_data, callback, 0, &zErrMsg);
    if( rc != SQLITE_OK ){
        std::cerr << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    }else{
        std::cerr << "Operation done successfully" << std::endl;
    }

    // 更新数据
    const char* sql_update_data = "UPDATE COMPANY set SALARY = 25000.00 where ID=1; "
                                  "SELECT * from COMPANY";
    rc = sqlite3_exec(db, sql_update_data, callback, 0, &zErrMsg);
    if( rc != SQLITE_OK ){
        std::cerr << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    }else{
        std::cerr << "Total updated: " << sqlite3_changes(db) << std::endl;
    }

    // 删除数据
    const char* sql_delete_data = "DELETE from COMPANY where ID=2; "
                                  "SELECT * from COMPANY";
    rc = sqlite3_exec(db, sql_delete_data, callback, 0, &zErrMsg);
    if( rc != SQLITE_OK ){
        std::cerr << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    }else{
        std::cerr << "Total deleted: " << sqlite3_changes(db) << std::endl;
    }

    sqlite3_close(db);
    return 0;
}

上述代码创建了一个名为“test.db”的数据库，并在其中创建名为“COMPANY”的表。接着，插入了几条记录，并查询了所有记录。然后，更新了一条记录，并查询了所有记录。最后，删除了一条记录，并查询了所有记录。

注意：以上代码仅为示例，实际应用中需要根据具体情况进行修改。