mysql 学习

 1 #-----------------------------------
 2 #1.正则表达式检索 [RegexP]
 3 #-----------------------------------
 4 # * Binary字段可以支持大小写匹配
 5 # * 文本开始^(集合中是否定) 结束$
 6 select * from goods where bid RegexP Binary ‘E|a‘        # * | 为或
 7 select * from goods where bid RegexP Binary ‘[123]Ton‘   # * [123]Ton为匹配   1Ton 2Ton 3Ton
 8 select * from goods where bid RegexP Binary ‘[1-3]Ton‘     * 同上
 9 select * from goods where bid RegexP Binary ‘[^123]Ton‘  # * [123]Ton为不匹配 1Ton 2Ton 3Ton
10 select * from goods where bid RegexP Binary ‘\\.‘        # * 匹配特殊字符需要\\转义
11                                                            * 也可以匹配元字符, \\f \\n \\r \\t \\v
12
13 select ‘justalnums‘ REGEXP ‘[[:alpha:]]‘;                # * [:alpha:] 为任意字符(同[a-zA-Z])
14                                                            * 其他character class:
15                                                              alnum,blank,cntrl,digit,graph,lower,print,punct,space,upper,xdigit
16
17 select ‘***‘ RegexP ‘\\([0-9] sticks?)\\‘                #
18 select ‘***‘ RegexP ‘[[:digit:]]{4}‘                     # 存在4位数字的
19
20
21 #-----------------------------------
22 #2.函数
23 #-----------------------------------
24 字符函数
25 * IFNull() = COALESCE()
26 时间函数
27 * now(),curdate(),curtime(),dayofweek(now()) *第一日是周日
28 * addDate(DataChange_CreateTime,-1),AddTime(DataChange_CreateTime,-1)
29 * Date(DataChange_CreateTime),year(DataChange_CreateTime),month(DataChange_CreateTime),day(DataChange_CreateTime)
30 * time(DataChange_CreateTime),hour(DataChange_CreateTime),minute(DataChange_CreateTime),second(DataChange_CreateTime)
31 * DATE_FORMAT(NOW(),‘%b %d %Y %h:%i %p‘)
32 * date_add(DataChange_CreateTime, interval 1 DAY_MINUTE)  * 增
33 * date_sub(DataChange_CreateTime, interval 1 DAY_MINUTE)  * 减
34
35 * SELECT now(),unix_timestamp( now() ),from_unixtime(unix_timestamp( now() ))  *UTC系统时间戳 与 当前时区timestamp 转换
36
37 数值函数
38 floor()向上取整   round()四舍五入   rand()随机数   ceil() ceiling()向下取整
39
40
41 #-----------------------------------
42 #3.游标
43 #-----------------------------------
44 delimiter //
45 CREATE PROCEDURE TestCursor()
46 BEGIN
47   DECLARE v_id    INT;
48   DECLARE v_value VARCHAR(10);
49
50   -- 游标控制的标志
51   DECLARE no_more_departments INT;
52
53   -- 定义游标.
54   DECLARE c_test_main CURSOR
55   FOR
56   SELECT goodsid,cast(now() as CHAR) as  value FROM goods;
57
58   -- 当游标没有数据的时候
59   -- 设置 no_more_departments = 1
60   DECLARE CONTINUE HANDLER
61   FOR
62   NOT FOUND SET no_more_departments=1;
63
64   -- 设置初始标志位，认为游标是有数据的.
65   SET no_more_departments=0;
66
67   -- 打开游标
68   OPEN c_test_main;
69
70   -- 获取游标数据
71   FETCH c_test_main INTO v_id, v_value;
72
73   -- 循环所有的行
74   WHILE no_more_departments = 0 DO
75     -- 输出调试信息
76     SELECT v_id, v_value;
77     -- 获取游标数据
78     FETCH c_test_main INTO v_id, v_value;
79   END WHILE;
80
81   -- 关闭游标
82   CLOSE c_test_main;
83 END
84 //
85
86 #drop procedure TestCursor;
87 CALL  TestCursor();