erlang连接mysql数据库后为什么fetch说匹配不到这个函数

发布网友发布时间：2022-05-07 05:48

共2个回答

热心网友时间：2022-05-07 07:17

需要注意，官方放在googlecode的测试代码已经旧了，fetch接口实际上需要一个二进制list，所以是[<<"select * from table">>]格式，而不是<<”select * from table”>>格式。

以下是增、删、改、查操作的测试代码：

-mole(mysql_test).
-export([start/0]).

start () ->

    % 连接数据库
    mysql:start_link(conn1, "localhost", "root", "ybybyb", "webgame"),

    % 插入数据
    Result1 = mysql:fetch(
        conn1,
        [<<
        "INSERT INTO"
        "        `player`"
        "    SET"
        "        `username`         = 'test',"
        "        `joined_datetime`  = now(),"
        "        `logined_datetime` = now();"
        >>]
    ),

    io:format("Result1: ~p~n", [Result1]),

    % 查询数据
    Result2 = mysql:fetch(conn1, [<<"SELECT * FROM player">>]),

    io:format("Result2: ~p~n", [Result2]),

    % 更新数据
    Result3 = mysql:fetch(
        conn1,
        [<<
        "UPDATE"
        "    `player`"
        "SET"
        "    `username` = 'test_player'"
        "where"
        "    `username` = 'test'"
        >>]
    ),

    io:format("Result3: ~p~n", [Result3]),

    % 查询数据
    Result4 = mysql:fetch(conn1, [<<"SELECT * FROM player">>]),

    io:format("Result4: ~p~n", [Result4]),

    % 删除数据
    Result5 = mysql:fetch(
        conn1,
        [<<
        "DELETE FROM `player` WHERE `username` = 'test_player'"
        >>]
    ),

    io:format("Result5: ~p~n", [Result5]),

    % 查询数据
    Result6 = mysql:fetch(conn1, [<<"SELECT * FROM player">>]),

    io:format("Result4: ~p~n", [Result6]),

    ok.