study mysql

SELECT
    CONCAT(`_1`.`drop_default`,`_1`.`alter_default`,`_1`.`update_default`) AS `sql`
FROM (
    -- 设置默认值
    SELECT 

    -- ALTER TABLE testalter_tbl ALTER i DROP DEFAULT;
    CONCAT ('ALTER TABLE',' `',`tt`.`table_name`,'` ','ALTER',' `',`col`.`column_name`,'` ','DROP DEFAULT;') AS `drop_default`,
    -- ALTER TABLE testalter_tbl ALTER i SET DEFAULT 1000;
    CONCAT ('ALTER TABLE',' `',`tt`.`table_name`,'` ','ALTER',' `',`col`.`column_name`,'` ','SET DEFAULT \'\';') AS `alter_default`,
    -- UPDATE testalter_tbl SET i = 1000 WHERE ...;
    CONCAT ('UPDATE',' `',`tt`.`table_name`,'` ','SET',' `',`col`.`column_name`,'` ','=',' ','\'\'',' ','WHERE',' `',`col`.`column_name`,'` ','IS NULL;') AS `update_default`

    FROM `information_schema`.`columns` AS `col`
    INNER JOIN `information_schema`.`tables` AS `tt` ON (
        `col`.`table_name` = `tt`.`table_name`
    )
    WHERE (
        -- 对象类型(数据表)
        `tt`.`table_type` = 'BASE TABLE'
        -- 架构名称(数据库名称)
        AND `col`.`table_schema` = 'aigezhe'
        AND (
            -- 字符串类型
            `col`.`data_type` = 'char'
            -- OR `col`.`data_type` = 'longtext'
            -- OR `col`.`data_type` = 'mediumtext'
            -- OR `col`.`data_type` = 'text'
            -- OR `col`.`data_type` = 'tinytext'
            OR `col`.`data_type` = 'varchar' 

            -- 日期和时间类型
            -- `col`.`data_type` = 'date'
            -- OR `col`.`data_type` = 'time'
            -- OR `col`.`data_type` = 'year'
            -- OR `col`.`data_type` = 'datetime'
            -- OR `col`.`data_type` = 'timestamp' 

            -- 数值类型
            -- `col`.`data_type` = 'tinyint'
            -- OR `col`.`data_type` = 'smallint'
            -- OR `col`.`data_type` = 'mediumint'
            -- OR `col`.`data_type` = 'int'
            -- OR `col`.`data_type` = 'bigint'
            -- OR `col`.`data_type` = 'float'
            -- OR `col`.`data_type` = 'double'
            -- OR `col`.`data_type` = 'decimal'
        )
    )
) AS `_1`;

-- ----------------------------
-- SP函数的语法练习
-- ----------------------------
DROP FUNCTION IF EXISTS `函数名称`;
DELIMITER $$
CREATE FUNCTION `函数名称`(/*函数参数*/)
-- 函数返回值
RETURNS VARCHAR(255)
BEGIN

END $$
DELIMITER ;

-- ----------------------------
-- SP过程的语法练习
-- ----------------------------
DROP PROCEDURE IF EXISTS `过程名称`;
DELIMITER $$
CREATE PROCEDURE `过程名称`(/*过程参数*/)
BEGIN

END $$
DELIMITER ;

-- 一个 test 过程
DELIMITER $$
DROP PROCEDURE IF EXISTS `test` $$
CREATE PROCEDURE `test`(out rtn int)
BEGIN
    declare LoginId int default 0;
    set rtn = 1;
    if (LoginId = 3) then
        set rtn = 2;
    elseif (LoginId = 0) then
        set rtn = 3;
    else
        set rtn = 4;
    end if;
END $$
DELIMITER ;

-- ----------------------------
-- 创建函数
-- ----------------------------
set global log_bin_trust_function_creators=TRUE;
-- set global log_bin_trust_function_creators=1;
SET @RAND_NUM = '';
SET @RAND_EN = 'abcdefghijklmnopqrstuvwxyzABCDEFJHIJKLMNOPQRSTUVWXYZ';
SET @RAND_ZHCN = '们以我到他会作时要动国产的一是工就年阶义发成部民可出能方进在了不和有大这主中人上为来分生对于学下级地个用同行面说种过命度革而多子后自社加小机也经力线本电高量长党得实家定深法表着水理化争现所二起政三好十战无农使性前等反体合斗路图把结第里正新开论之物从当两些还天资事队批点育重其思与间内去因件日利相由压员气业代全组数果期导平各基或月毛然如应形想制心样干都向变关问比展那它最及外没看治提五解系林者米群头意只明四道马认次文通但条较克又公孔领军流入接席位情运器并飞原油放立题质指建区验活众很教决特此常石强极土少已根共直团统式转别造切九你取西持总料连任志观调七么山程百报更见必真保热委手改管处己将修支识病象几先老光专什六型具示复安带每东增则完风回南广劳轮科北打积车计给节做务被整联步类集号列温装即毫知轴研单色坚据速防史拉世设达尔场织历花受求传口断况采精金界品判参层止边清至万确究书术状厂须离再目海交权且儿青才证低越际八试规斯近注办布门铁需走议县兵固除般引齿千胜细影济白格效置推空配刀叶率述今选养德话查差半敌始片施响收华觉备名红续均药标记难存测士身紧液派准斤角降维板许破述技消底床田势端感往神便贺村构照容非搞亚磨族火段算适讲按值美态黄易彪服早班麦削信排台声该击素张密害侯草何树肥继右属市严径螺检左页抗苏显苦英快称坏移约巴材省黑武培著河帝仅针怎植京助升王眼她抓含苗副杂普谈围食射源例致酸旧却充足短划剂宣环落首尺波承粉践府鱼随考刻靠够满夫失包住促枝局菌杆周护岩师举曲春元超负砂封换太模贫减阳扬江析亩木言球朝医校古呢稻宋听唯输滑站另卫字鼓刚写刘微略范供阿块某功套友限项余倒卷创律雨让骨远帮初皮播优占死毒圈伟季训控激找叫云互跟裂粮粒母练塞钢顶策双留误础吸阻故寸盾晚丝女散焊功株亲院冷彻弹错散商视艺灭版烈零室轻血倍缺厘泵察绝富城冲喷壤简否柱李望盘磁雄似困巩益洲脱投送奴侧润盖挥距触星松送获兴独官混纪依未突架宽冬章湿偏纹吃执阀矿寨责熟稳夺硬价努翻奇甲预职评读背协损棉侵灰虽矛厚罗泥辟告卵箱掌氧恩爱停曾溶营终纲孟钱待尽俄缩沙退陈讨奋械载胞幼哪剥迫旋征槽倒握担仍呀鲜吧卡粗介钻逐弱脚怕盐末阴丰雾冠丙街莱贝辐肠付吉渗瑞惊顿挤秒悬姆烂森糖圣凹陶词迟蚕亿矩康遵牧遭幅园腔订香肉弟屋敏恢忘编印蜂急拿扩伤飞露核缘游振操央伍域甚迅辉异序免纸夜乡久隶缸夹念兰映沟乙吗儒杀汽磷艰晶插埃燃欢铁补咱芽永瓦倾阵碳演威附牙芽永瓦斜灌欧献顺猪洋腐请透司危括脉宜笑若尾束壮暴企菜穗楚汉愈绿拖牛份染既秋遍锻玉夏疗尖殖井费州访吹荣铜沿替滚客召旱悟刺脑措贯藏敢令隙炉壳硫煤迎铸粘探临薄旬善福纵择礼愿伏残雷延烟句纯渐耕跑泽慢栽鲁赤繁境潮横掉锥希池败船假亮谓托伙哲怀割摆贡呈劲财仪沉炼麻罪祖息车穿货销齐鼠抽画饲龙库守筑房歌寒喜哥洗蚀废纳腹乎录镜妇恶脂庄擦险赞钟摇典柄辩竹谷卖乱虚桥奥伯赶垂途额壁网截野遗静谋弄挂课镇妄盛耐援扎虑键归符庆聚绕摩忙舞遇索顾胶羊湖钉仁音迹碎伸灯避泛亡答勇频皇柳哈揭甘诺概宪浓岛袭谁洪谢炮浇斑讯懂灵蛋闭孩释乳巨徒私银伊景坦累匀霉杜乐勒隔弯绩招绍胡呼痛峰零柴簧午跳居尚丁秦稍追梁折耗碱殊岗挖氏刃剧堆赫荷胸衡勤膜篇登驻案刊秧缓凸役剪川雪链渔啦脸户洛孢勃盟买杨宗焦赛旗滤硅炭股坐蒸凝竟陷枪黎救冒暗洞犯筒您宋弧爆谬涂味津臂障褐陆啊健尊豆拔莫抵桑坡缝警挑污冰柬嘴啥饭塑寄赵喊垫丹渡耳刨虎笔稀昆浪萨茶滴浅拥穴覆伦娘吨浸袖珠雌妈紫戏塔锤震岁貌洁剖牢锋疑霸闪埔猛诉刷狠忽灾闹乔唐漏闻沈熔氯荒茎男凡抢像浆旁玻亦忠唱蒙予纷捕锁尤乘乌智淡允叛畜俘摸锈扫毕璃宝芯爷鉴秘净蒋钙肩腾枯抛轨堂拌爸循诱祝励肯酒绳穷塘燥泡袋朗喂铝软渠颗惯贸粪综墙趋彼届墨碍启逆卸航衣孙龄岭骗休借';
DELIMITER $$
DROP FUNCTION IF EXISTS `rs` $$
CREATE FUNCTION `rs`(n int,type int)
returns varchar(1024)
BEGIN
    -- declare chars char(52) default 'abcdefghijklmnopqrstuvwxyzABCDEFJHIJKLMNOPQRSTUVWXYZ';
    declare res varchar(1024) default '';
    declare i int default 0;
    declare count int;
    declare chars text;
    if (n <= 0) then
        return res;
    else
        if (n >= 1024) then
            set n = 1024;
        end if;
    end if;
    -- 判断采用那种字体
    if (type = 1) then
        -- 采用中文
        set count = 1500;
    else
        if (type = 2) then
            -- 采用英文
            set count = 52;
        else
            -- 采用数字
            set count = 10;
        end if;
    end if;
    repeat
    set i = i + 1;
    -- 判断采用那种字体
    if (type = 1) then
        -- 采用中文
        set res = concat(res,substring(@RAND_ZHCN,floor(1+rand()*count),1));
    else
        if (type = 2) then
            -- 采用英文
            set res = concat(res,substring(@RAND_EN,floor(1+rand()*count),1));
        else
            -- 采用数字
            set res = concat(res,substring(@RAND_NUM,floor(1+rand()*count),1));
        end if;
    end if;
    until i = n end repeat;
    return res;
END $$
DELIMITER ;
-- ----------------------------
-- 创建存储过程
-- ----------------------------
DELIMITER $$
DROP PROCEDURE IF EXISTS `inst` $$
CREATE PROCEDURE `inst`(n int)
BEGIN

    declare i int default 0;
    set autocommit = 0;

    if (n > 0) then
        repeat
            set i = i + 1;
            insert into `user` (`nickname`,`realname`,`age`,`sex`,`phone`,`telephone`) values (rs(floor(2+rand()*3),1),rs(floor(2+rand()*3),1),floor(10+rand()*90),floor(1+rand()*2),concat('',rs(10,3)),concat('023-',rs(8,3)));
        until i = n end repeat;
    end if;
    commit;
    set autocommit = 1;

END $$
DELIMITER ;

DROP PROCEDURE IF EXISTS `inst_one`;
DELIMITER $$
CREATE PROCEDURE `inst_one`(
    in id int,
    in nickname varchar(50),
    in realname varchar(50),
    in age tinyint(3) unsigned,
    in sex tinyint(1) unsigned,
    in phone varchar(30),
    in telephone varchar(30)
)
BEGIN

    set autocommit = 0;
    insert into `user` (`nickname`,`realname`,`age`,`sex`,`phone`,`telephone`) values (nickname,realname,age,sex,phone,telephone);
    commit;
    rollback;
    set autocommit = 1;

END $$
DELIMITER ;

-- ----------------------------
-- Table structure for `user`
-- ----------------------------
CREATE TABLE IF NOT EXISTS `user` (
    `id` int unsigned NOT NULL AUTO_INCREMENT COMMENT '自增ID',
    `nickname` varchar(50) NOT NULL DEFAULT '' COMMENT '昵称',
    `realname` varchar(50) NOT NULL DEFAULT '' COMMENT '真实姓名',
    `age` tinyint(3) unsigned NOT NULL DEFAULT 0 COMMENT '年龄',
    `sex` tinyint(1) unsigned NOT NULL DEFAULT 0 COMMENT '1-男,2-女',
    `phone` varchar(30) NOT NULL DEFAULT '' COMMENT '手机号码',
    `telephone` varchar(30) NOT NULL DEFAULT '' COMMENT '联系电话',
    `type` tinyint(3) NOT NULL DEFAULT 1 COMMENT '1-普通用户',
    `createtime` int(10) unsigned NOT NULL DEFAULT 0 COMMENT '创建时间',
    `createts` timestamp DEFAULT CURRENT_TIMESTAMP COMMENT '系统创建时间',
    `updatetime` int(10) unsigned NOT NULL DEFAULT 0 COMMENT '修改时间',
    `updatets` datetime COMMENT '系统修改时间',
    PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COMMENT '用户管理表';
-- ----------------------------
-- TRIGGER structure for `update_user_trigger`
-- ----------------------------
DROP TRIGGER IF EXISTS `update_user_trigger`;
DELIMITER //
CREATE TRIGGER `update_user_trigger` BEFORE UPDATE ON `user`
FOR EACH ROW SET NEW.`updatets` = NOW()
//
DELIMITER ;

-- ----------------------------
-- Table structure for `user_address`
-- ----------------------------
CREATE TABLE IF NOT EXISTS `user_address` (
    `id` int unsigned NOT NULL AUTO_INCREMENT COMMENT '自增ID',
    `name` varchar(255) NOT NULL DEFAULT '' COMMENT '地址名称',
    `prov` varchar(30) NOT NULL DEFAULT '' COMMENT '省',
    `city` varchar(30) NOT NULL DEFAULT '' COMMENT '市',
    `zone` varchar(30) NOT NULL DEFAULT '' COMMENT '区',
    `lon` varchar(50) NOT NULL DEFAULT '' COMMENT '经度',
    `lat` varchar(50) NOT NULL DEFAULT '' COMMENT '纬度',
    `type` tinyint(3) NOT NULL DEFAULT 1 COMMENT '1-默认地址',
    `createtime` int(10) unsigned NOT NULL DEFAULT 0 COMMENT '创建时间',
    `createts` timestamp DEFAULT CURRENT_TIMESTAMP COMMENT '系统创建时间',
    `updatetime` int(10) unsigned NOT NULL DEFAULT 0 COMMENT '修改时间',
    `updatets` datetime COMMENT '系统修改时间',
    `userid` int unsigned COMMENT '用户id',
    PRIMARY KEY (`id`),
    CONSTRAINT `FK_userid` FOREIGN KEY (`userid`) REFERENCES `user`(`userid`) ON DELETE SET NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COMMENT '用户地址管理表';
-- ----------------------------
-- TRIGGER structure for `update_user_address_trigger`
-- ----------------------------
DROP TRIGGER IF EXISTS `update_user_address_trigger`;
DELIMITER //
CREATE TRIGGER `update_user_address_trigger` BEFORE UPDATE ON `user_address`
FOR EACH ROW SET NEW.`updatets` = NOW()
//
DELIMITER ;

/**
 *
 *
 *
 * 补充：自定义函数相关内容
 *
 *
 */
/**
* 1.自定义示例
**/
-- 无参函数定义
DROP FUNCTION IF EXISTS `hello`;
DELIMITER $$
CREATE FUNCTION `hello`()
RETURNS VARCHAR(255)
BEGIN
    RETURN 'Hello world,i am mysql';
END $$
DELIMITER ;
SELECT hello();
-- 含有参数的自定义函数
DROP FUNCTION IF EXISTS `aiyu`.`formDate`;
DELIMITER $$
CREATE FUNCTION `aiyu`.`formDate`(fdate DATETIME)
RETURNS VARCHAR(255)
BEGIN
    DECLARE x VARCHAR(255) DEFAULT '';
    SET x = DATE_FORMAT(fdate,'%Y年%m月%d日 %H时%i分%s秒');
    RETURN x;
END $$
DELIMITER ;
SELECT formDate(NOW());
/**
* 2.自定义函数相关语法及变量
**/
-- 变量声明
DECLARE var_name[,...] type [DEFAULT value]
SELECT col_name[,...] INTO var_name[,...] table_expr
-- IF  条件语句
IF search_condition THEN
statement_list
[ELSEIF search_condition THEN statement_list]
...
[ELSE statement_list]
END IF
-- CASE语句
CASE case_value
WHEN when_value THEN statement_list
[WHEN when_value THEN statement_list]
...
[ELSE statement_list]
END CASE;
-- 循环语句
WHILE
[begin_label:]WHILE search_condition DO
statement_list
END WHILE [begin_label];
退出整个循环leave 相当于break
退出当前循环iterate 相当于 continue
通过退出的标签决定退出哪个循环。
-- 其他相关
删除函数我们可以使用 DROP FUNCTION IF EXISTS function_name;
查看定义的函数  SHOW FUCNTION STATUS LIKE 'function_name'，或者是使用SHOW  CREATE FUNCTION function_name;

/**
 *
 *
 * MySQL存储过程中实现执行动态SQL语句的方法
 *
 *
 */
mysql>
mysql> delimiter $$
mysql>
mysql> CREATE PROCEDURE set_col_value
  ->    (in_table   VARCHAR(128),
  ->     in_column  VARCHAR(128),
  ->     in_new_value VARCHAR(1000),
  ->     in_where   VARCHAR(4000))
  ->
  -> BEGIN
  ->  DECLARE l_sql VARCHAR(4000);
  ->  SET l_sql=CONCAT_ws(' ',
  ->        'UPDATE',in_table,
  ->          'SET',in_column,'=',in_new_value,
  ->        ' WHERE',in_where);
  ->  SET @sql=l_sql;
  ->  PREPARE s1 FROM @sql;
  ->  EXECUTE s1;
  ->  DEALLOCATE PREPARE s1;
  -> END$$
Query OK, 0 rows affected (0.00 sec)

当然也可以利用临时表来创建，

感谢波波的分享。

#mysql 存储过程中利用游标循环结果集
<p>有这么个需求</p><p>
</p><p>topic表中有id 和comments数量</p><p>
</p><p>commemt表中有 topicid 和id</p><p>
由于历史原因，【删除评论表中时未同步删除topic中评论数量的值】，</p><p>所以要求一条语句执行更新。（当然用php写个foreach也可以）。  

<pre name="code" class="sql">drop procedure if exists add_demo;
# 创建存储过程 add_test  

CREATE PROCEDURE add_demo()  

    BEGIN
           #定义 变量
            #a 评论数量
            #b id话题  

           DECLARE a int;
           DECLARE b int;
           #此变可有可无，为了给个该存储函数执行成功后给个提示，运行下便知道  

           DECLARE str VARCHAR(300);
           DECLARE x int default 123;
           #这个用于处理游标到达最后一行的情况  

           DECLARE s int default 0;  

           #声明游标cursor_name（cursor_name是个多行结果集）  

           DECLARE cursor_name CURSOR FOR select count(topicid), topicid from t_comment group by topicid;  

           #设置一个终止标记   

           DECLARE CONTINUE HANDLER FOR SQLSTATE '' SET s=1;  

            set str = "--";
                #打开游标  

                OPEN cursor_name;  

                    #获取游标当前指针的记录，读取一行数据并传给变量a,b  

                    fetch  cursor_name into a,b;
                    #开始循环，判断是否游标已经到达了最后作为循环条件   

                    while s <> 1 do
                            set str =  concat(str,b);  

                            update t_topic set comments =a where id =b;
                            #读取下一行的数据  

                            fetch  cursor_name into a,b;  

                    end while;  

                 #关闭游标  

                 CLOSE cursor_name ;  

            select str;  

            set @aa='';
            select @aa;  

    #语句执行结束
    END;
    #调用存储函数add_test  

    CALL add_demo()  

decimal的用法

* decimal(较常用) 
* decimal(M,D) - (10,0) -(M-D个9).(D个9) ~ (M-D个9).(D个9)
* decimal(10,0) -> -9999999999 ~ 9999999999
* decimal(6,2) -> -9999.99 ~ 9999.99
* decimal(6,6) -> -0.999999 ~ 0.999999
* decimal(10,0) unsigned -> 0 ~ 9999999999
* decimal(6,2) unsigned -> 0 ~ 9999.99
* decimal(6,6) unsigned -> 0 ~ 0.999999