[root@C03-12U-26 testcontract]# cat testcontract.cpp

#include <eosiolib/eosio.hpp>  

class [[eosio::contract]] testcontract : public eosio::contract

{

public:

    testcontract( eosio::name receiver, eosio::name code, eosio::datastream<const char*> ds )

        : eosio::contract(receiver, code, ds),  _students(receiver, code.value)

    {}  

    //添加学生

    [[eosio::action]]

    void add(eosio::name user, std::string studentName,std::string studentGender,uint32_t studentAge,uint32_t studentHeight)

    {

        require_auth(user);

        eosio::print("Add student ", studentName);

        _students.emplace(get_self(), [&](auto& p) {

            p.id = _students.available_primary_key();

            p.studentName = studentName;

            p.studentGender = studentGender;

            p.studentAge = studentAge;

            p.studentHeight = studentHeight;

        });

    }  

    //根据主键删除学生

    [[eosio::action]]

    void del(eosio::name user, uint64_t id)

    {

        require_auth(user);

        eosio::print("Del student", id);

        auto itr = _students.find(id);

        if (itr != _students.end()) {

            _students.erase(itr);

        }

    }  

    //根据主键修改学生

    [[eosio::action]]

    void update(eosio::name user, uint64_t id,std::string studentName,std::string studentGender,uint32_t studentAge,uint32_t studentHeight)

    {

        require_auth(user);

        eosio::print("update student", studentName);

        auto itr = _students.find(id);

        if (itr != _students.end())

        {

            _students.modify(itr, user, [&]( auto& p ) {

                p.studentName = studentName;

                p.studentGender = studentGender;

                p.studentAge = studentAge;

                p.studentHeight = studentHeight;

            });

        }

    }  

    //清空表,待定

    [[eosio::action]]

    void clear(eosio::name user)

    {

        require_auth(user);

        std::vector<uint64_t> keysForDeletion;

        for(auto& item : _students) {

            keysForDeletion.push_back(item.id);

        }  

        for (uint64_t key : keysForDeletion) {

            eosio::print("remove from _students ", key);

            auto itr = _students.find(key);

            if (itr != _students.end()) {

                _students.erase(itr);

            }

        }

    }  

    //private: -- not private so the cleos get table call can see the table data.

    // create the multi index tables to store the data

    struct [[eosio::table]] students

    {

        uint64_t      id; // primary key

        std::string   studentName;

        std::string   studentGender;

        uint32_t    studentAge;

        uint32_t    studentHeight;  

        uint64_t primary_key() const { return id; }

        uint64_t by_age() const {return studentAge; }

    };  

    //数据表根据age排序

    typedef eosio::multi_index<"students"_n, students, eosio::indexed_by<"studentage"_n, eosio::const_mem_fun<students, uint64_t, &students::by_age>>> studentstable;  

    //students数据库表

    studentstable _students;

};  

EOSIO_DISPATCH( testcontract, (add)(del)(update)(clear))

cleos -u https://jungle2.cryptolions.io:443  wallet unlock -n zmcheng-wallet

cleos -u https://jungle2.cryptolions.io:443 set contract zmcheng12345 /root/github.com/testcontract -p zmcheng12345@active

[root@C03-12U-26 testcontract]# cleos -u https://jungle2.cryptolions.io:443 push action zmcheng12345 add '["zmcheng12345","zmcheng","male",25,170]' -p zmcheng12345@active

executed transaction: a64271659aea1ce07fd05a4ff1bb0188c441de04263f3a18b819cbee205d2bbd  128 bytes  273 us

#  zmcheng12345 <= zmcheng12345::add            {"user":"zmcheng12345","studentName":"zmcheng","studentGender":"male","studentAge":25,"studentHeight...

>> Add student zmcheng

warning: transaction executed locally, but may not be confirmed by the network yet         ]

[root@C03-12U-26 testcontract]# cleos -u https://jungle2.cryptolions.io:443 get table zmcheng12345 zmcheng12345 students

{

  "rows": [{

      "id": 0,

      "studentName": "zmcheng",

      "studentGender": "male",

      "studentAge": 25,

      "studentHeight": 170

    },{

      "id": 1,

      "studentName": "www",

      "studentGender": "male",

      "studentAge": 26,

      "studentHeight": 170

    }

  ],

  "more": false

}

[root@C03-12U-26 testcontract]# cleos -u https://jungle2.cryptolions.io:443 push action zmcheng12345 update '["zmcheng12345",1,"www","male",12,123]' -p zmcheng12345@active

executed transaction: 765c35452964de54771c3fe505daad272a8a53ec61954a2cc43350f7f84e86e3  128 bytes  213 us

#  zmcheng12345 <= zmcheng12345::update         {"user":"zmcheng12345","id":1,"studentName":"www","studentGender":"male","studentAge":12,"studentHei...

>> update studentwww

warning: transaction executed locally, but may not be confirmed by the network yet         ]

[root@C03-12U-26 testcontract]# cleos -u https://jungle2.cryptolions.io:443 get table zmcheng12345 zmcheng12345 students

{

  "rows": [{

      "id": 0,

      "studentName": "zmcheng",

      "studentGender": "male",

      "studentAge": 25,

      "studentHeight": 170

    },{

      "id": 1,

      "studentName": "www",

      "studentGender": "male",

      "studentAge": 12,

      "studentHeight": 123

    }

  ],

  "more": false

}

[root@C03-12U-26 testcontract]#

[root@C03-12U-26 testcontract]# cleos -u https://jungle2.cryptolions.io:443 push action zmcheng12345 del '["zmcheng12345",1]' -p zmcheng12345@active

executed transaction: 1a64a42ebccac0f9b7061c42a0fa8daaebe7b1a18db1cb058fe479608ee9170a  112 bytes  255 us

#  zmcheng12345 <= zmcheng12345::del            {"user":"zmcheng12345","id":1}

>> Del student1

warning: transaction executed locally, but may not be confirmed by the network yet         ]

[root@C03-12U-26 testcontract]# cleos -u https://jungle2.cryptolions.io:443 get table zmcheng12345 zmcheng12345 students

{

  "rows": [{

      "id": 0,

      "studentName": "zmcheng",

      "studentGender": "male",

      "studentAge": 25,

      "studentHeight": 170

    }

  ],

  "more": false

}