Mysql存储过程知识，案例

Mysql存储过程知识，案例：

create procedure delete_setting(in p_settingid integer)
begin
delete
from	setting
where	settingid=p_settingid;
end

select `name` from mysql.proc where db = 'your_db_name' and `type` = 'PROCEDURE'

show procedure status;

show create procedure proc_name;

show create function func_name;

局部变量

create  procedure test3(out number1 integer)
begin
declare number2 integer default 100;
set number1=number2;
end

call test(@number)

select @number#

默认值为标量子查询

create procedure test2(out ta integer)
begin
declare tt integer default (select count(*) from `setting`);
set ta=tt;
end

流程控制

IF

create procedure getMax(in p1 integer,in p2 integer,out p3 integer)
begin
if p1>p2 then
set p3 = p1;
elseif p1<p2 then
set p3 = p2;
else
set p3=0;
end if;
end

fibonnaci

create procedure fibonnaci(inout n1 integer,inout n2 integer,inout n3 integer)
begin
set n3=n1+n2;
if n3>1000 then
set n3 = n3-1000;
end if;
set n1=n2;
set n2=n3;
end

create procedure largest(out t char(30))
begin
if (select count(*) from product)>(select count(*) from productcategory) then
set t="product";
elseif (select count(*) from product)<(select count(*) from productcategory) then
set t="productcategory";
else
set t = "equal";
end if;
end

create procedure small_exit(out p1 integer,out p2 integer)
begin
set p1 = 1;
set p2 = 2;
block1:begin
leave block1;
set p2 = 3;
end;
set p1=4;
end

WHILE  计算两个相差的年月日

create procedure age(
in start_date date,
in end_date   date,
out years integer,
out monthes integer,
out days integer
)
begin
declare next_date,previous_date date;

set years = 0;
set previous_date=start_date;
set next_date =start_date+interval 1 year;
while next_date<end_date do
set years = years+1;
set previous_date = next_date;
set next_date = next_date+ interval 1 year;
end while;

set monthes = 0;
set next_date = previous_date + interval 1 month;
while next_date<end_date do
set monthes = monthes +1;
set previous_date=next_date;
set next_date = previous_date+interval 1 month;
end while;
end

————————————————————————
调用存储过程
建表
create table players_with_parents
(playerno	integer not null primary key,
father_playerno integer,
mother_playerno integer);

alter table players_with_parents add constraint fk_1
foreign key (father_playerno) references player_with_parents (playerno);

alter table players_with_parents add
foreign key (mother_playerno) references player_with_parents(playerno);

增加外键约束；

insert into players_with_parents values(9,null,null),(8,null,null),(7,null,null),(6,null,null),(5,null,null)
,(4,8,9),(3,6,7),(2,4,5),(1,2,3)

create procedure total_number_of_parents(in_playerno integer,inout number integer)
begin
declare v_father,v_mother integer;
set v_father =
(select father_playerno from players_with_parents where playerno=in_playerno);

set v_mother =
(select mother_playerno from players_with_parents where playerno=in_playerno);

if v_father is not null then
call total_number_of_parents(v_father,number);
set number = number+1;
end if;

if v_mother is not null then
call total_number_of_parents(v_mother,number);
set number = number+1;
end if;
end
set @num=0;
set max_sp_recursion_depth=100;
call total_number_of_parents(4,@num);
select @num;

select into

create procedure total_setting(out p1 integer)
begin
select count(*) into p1 from `setting`;
end

create procedure get_setting(out v_name varchar(60),out v_value varchar(60))
begin
select `name`,`value` into v_name,v_value from setting limit 0,1;
end

create procedure showErr(out p integer)
begin
set p=1;
insert into `setting` (`settingid`,`name`)values(12,'vname');
set p=2;
end

create procedure showErr(out p integer,out error integer)
begin
declare continue handler for sqlstat '23000'
set error = '200000';
declare continue handler for sqlstat '23001';
set error = '200001';
set error = '000000';
set p=1;
insert into `setting` (`settingid`,`name`)values(12,'vname');
set p=2;
end

declare continue handler for 1062 set error='23000';
declare continue handler for 1136 set error='21S01';

01 SQLWARING
02 NOT FOUND
SQLEXCEPTION 01,02以外的

create procedure addDate(out error char(5))
begin
declare continue handler for sqlstate '23000' set error='23000';
declare continue handler for sqlstate '21S01' set error='21S01';
set error='00000';
insert into `setting` values(15,'test','testValue',10);
end

declare non_unique condition for sqlstate '23000';
ddeclare continue handler for non_unique set error='23000';

同一块中，相同的错误，不能有两个或多个处理程序；

带有游标的存储过程
declare c_players cursor for select playerno from players;

create procedure number_of_players(out number integer)
begin
declare a_playerno integer;
declare found boolean default true;
declare c_players cursor for select playerno from players;
declare continue handler for not found set found=false;
set number=0;
open c_players;
fetch c_players into a_playerno;
while found do
set number =number+1;
fetch c_players into a_playerno;
end while;
close c_players;
end

create procedure number_of_setting(out number integer)
begin
declare a_settingid integer;
declare found boolean default true;
declare c_settingids cursor for select settingid from setting;
declare continue handler for not found set found=false;
set number=0;
open c_settingids;
fetch c_settingids into a_settingid;
while	found do
set number=number+1;
fetch c_settingids into a_settingid;
end while;
close c_settingids;
end

create procedure delete_older_than_30()
begin
declare v_age,v_playerno,v_years,v_months,v_days integer;
declare v_birth_date date;
declare found boolean default true;
declare c_players cursor for
select playerno,birth_date from players;
declare continue handler for not found set found=false;
open c_players;
fetch c_players into v_playerno,v_birth_date;
while found do
call age(v_birth_date,now(),v_years,v_months,v_days);
if v_years>30 then
delete from penalties where playerno=v_playerno;
end if;
fetch c_players into v_playno,v_birth_date;
end while;
close c_players;
end

commit,rollback,start transaction;

create function test(t1 integer,t2 integer) returns integer
begin
return t1+t2;
end

查询数据库中的存储过程

方法一：

select `name` from mysql.proc where db = 'your_db_name' and `type` = 'PROCEDURE'

方法二：

show procedure status;

查看存储过程或函数的创建代码

show create procedure proc_name;
show create function func_name;

查询数据库中的存储过程和函数

方法一：

select `name` from mysql.proc where db = 'your_db_name' and `type` = 'PROCEDURE' //存储过程
select `name` from mysql.proc where db = 'your_db_name' and `type` = 'FUNCTION' //函数

方法二：

show procedure status; //存储过程

show function status; //函数

查看存储过程或函数的创建代码

show create procedure proc_name;
show create function func_name;

查看视图

SELECT * from information_schema.VIEWS //视图

SELECT * from information_schema.TABLES //表

查看触发器

方法一：
语法：SHOW TRIGGERS [FROM db_name] [LIKE expr]
实例：SHOW TRIGGERS\G //触发器

方法二：
对INFORMATION_SCHEMA数据库中的TRIGGERS表查询
mysql>SELECT * FROM triggers T WHERE trigger_name=”mytrigger” \G

在存儲過程中使用 表名做变量传递：

PREPARE stmt_name FROM preparable_stmt;
EXECUTE stmt_name [USING @var_name [, @var_name] ...];
{DEALLOCATE | DROP} PREPARE stmt_name;

下面是示例：

DROP PROCEDURE IF EXISTS `newtable`;
CREATE PROCEDURE `newtable`(IN tname varchar(64))
BEGIN
SET @sqlcmd = CONCAT('CREATE TABLE ', tname, ' (id int NOT NULL AUTO_INCREMENT, name varchar(64) DEFAULT NULL, PRIMARY KEY (`id`))');
PREPARE stmt FROM @sqlcmd;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END;
call newtable('abc');

　再来一个示例：

create procedure ate(in t char(30))
begin
set @s=concat("alter table ",t," engine=innodb");
prepare stmt from @s;
execute stmt;
deallocate prepare stmt;
end
call ate('deal')#

　　

看下面的示例：

mysql> SET @s = 'SELECT SQRT(POW(?,2) + POW(?,2)) AS hypotenuse';
mysql> PREPARE stmt2 FROM @s;
mysql> SET @a = 6;
mysql> SET @b = 8;
mysql> EXECUTE stmt2 USING @a, @b;
+------------+
| hypotenuse |
+------------+
| 10 |
+------------+
mysql> DEALLOCATE PREPARE stmt2;

在sql中替换变量；

如果你的MySQL 版本是 5.0.7 或者更高的，你还可以在 LIMIT 子句中使用它，示例如下：

mysql> SET @a=1;mysql> PREPARE STMT FROM "SELECT * FROM tbl LIMIT ?";
mysql> EXECUTE STMT USING @a;
mysql> SET @skip=1; SET @numrows=5;
mysql> PREPARE STMT FROM "SELECT * FROM tbl LIMIT ?, ?";
mysql> EXECUTE STMT USING @skip, @numrows;

使用 PREPARE 的几个注意点：
A：PREPARE stmt_name FROM preparable_stmt;预定义一个语句，并将它赋给 stmt_name ，tmt_name 是不区分大小写的。
B： 即使 preparable_stmt 语句中的 ? 所代表的是一个字符串，你也不需要将 ? 用引号包含起来。
C： 如果新的 PREPARE 语句使用了一个已存在的 stmt_name ，那么原有的将被立即释放！ 即使这个新的 PREPARE 语句因为错误而不能被正确执行。
D： PREPARE stmt_name 的作用域是当前客户端连接会话可见。
E： 要释放一个预定义语句的资源，可以使用 DEALLOCATE PREPARE 句法。
F： EXECUTE stmt_name 句法中，如果 stmt_name 不存在，将会引发一个错误。
G： 如果在终止客户端连接会话时，没有显式地调用 DEALLOCATE PREPARE 句法释放资源，服务器端会自己动释放它。
H： 在预定义语句中，CREATE TABLE, DELETE, DO, INSERT, REPLACE, SELECT, SET, UPDATE, 和大部分的 SHOW 句法被支持。
I： PREPARE 语句不可以用于存储过程，自定义函数！但从 MySQL 5.0.13 开始，它可以被用于存储过程，仍不支持在函数中使用！

了解了PREPARE的用法，再用变量做表名就很容易了。不过在实际操作过程中还发现其他一些问题，比如变量定义，declare变量和set @var=value变量的用法以及参数传入的变量。

测试后发现，set @var=value这样定义的变量直接写在字符串中就会被当作变量转换，declare的变量和参数传入的变量则必须用CONCAT来连接。具体的原理没有研究。

EXECUTE stmt USING @a;这样的语句USING后面的变量也只能用set @var=value这种，declare和参数传入的变量不行。

另外php调用mysql存储过程的时候也碰到很多问题，总是出现PROCEDURE p can't return a result set in the given context这样的问题。

mysql存储过程基本函数

一.字符串类

CHARSET(str) //返回字串字符集
CONCAT (string2 [,... ]) //连接字串
INSTR (string ,substring ) //返回substring首次在string中出现的位置,不存在返回0
LCASE (string2 ) //转换成小写
LEFT (string2 ,length ) //从string2中的左边起取length个字符
LENGTH (string ) //string长度
LOAD_FILE (file_name ) //从文件读取内容
LOCATE (substring , string [,start_position ] ) 同INSTR,但可指定开始位置
LPAD (string2 ,length ,pad ) //重复用pad加在string开头,直到字串长度为length
LTRIM (string2 ) //去除前端空格
REPEAT (string2 ,count ) //重复count次
REPLACE (str ,search_str ,replace_str ) //在str中用replace_str替换search_str
RPAD (string2 ,length ,pad) //在str后用pad补充,直到长度为length
RTRIM (string2 ) //去除后端空格
STRCMP (string1 ,string2 ) //逐字符比较两字串大小,
SUBSTRING (str , position [,length ]) //从str的position开始,取length个字符,
注：mysql中处理字符串时，默认第一个字符下标为1 ，即参数position必须大于等于1
mysql> select substring(’abcd’,0,2);
+———————–+
| substring(’abcd’,0,2) |
+———————–+
| |
+———————–+
1 row in set (0.00 sec)
mysql> select substring(’abcd’,1,2);
+———————–+
| substring(’abcd’,1,2) |
+———————–+
| ab |
+———————–+
1 row in set (0.02 sec)
TRIM([[BOTH|LEADING|TRAILING] [padding] FROM]string2) //去除指定位置的指定字符
UCASE (string2 ) //转换成大写
RIGHT(string2,length) //取string2最后length个字符
SPACE(count) //生成count个空格

二.数学类

ABS (number2 ) //绝对值
BIN (decimal_number ) //十进制转二进制
CEILING (number2 ) //向上取整
CONV(number2,from_base,to_base) //进制转换
FLOOR (number2 ) //向下取整
FORMAT (number,decimal_places ) //保留小数位数
HEX (DecimalNumber ) //转十六进制
注：HEX()中可传入字符串，则返回其ASC-11码，如 HEX(’DEF’)返回4142143
也可以传入十进制整数，返回其十六进制编码，如HEX(25)返回19
LEAST (number , number2 [,..]) //求最小值
MOD (numerator ,denominator ) //求余
POWER (number ,power ) //求指数
RAND([seed]) //随机数
ROUND (number [,decimals ]) //四舍五入,decimals为小数位数]
注：返回类型并非均为整数，如：
(1)默认变为整形值
mysql> select round(1.23);
+————-+
| round(1.23) |
+————-+
| 1 |
+————-+
1 row in set (0.00 sec)
mysql> select round(1.56);
+————-+
| round(1.56) |
+————-+
| 2 |
+————-+
1 row in set (0.00 sec)

(2)可以设定小数位数，返回浮点型数据
mysql> select round(1.567,2);
+—————-+
| round(1.567,2) |
+—————-+
| 1.57 |
+—————-+
1 row in set (0.00 sec)

SIGN (number2 ) //返回符号,正负或0
SQRT(number2) //开平方

三.日期时间类

ADDTIME (date2 ,time_interval ) //将time_interval加到date2
CONVERT_TZ (datetime2 ,fromTZ ,toTZ ) //转换时区
CURRENT_DATE ( ) //当前日期
CURRENT_TIME ( ) //当前时间
CURRENT_TIMESTAMP ( ) //当前时间戳
DATE (datetime ) //返回datetime的日期部分
DATE_ADD (date2 , INTERVAL d_value d_type ) //在date2中加上日期或时间
DATE_FORMAT (datetime ,FormatCodes ) //使用formatcodes格式显示datetime
DATE_SUB (date2 , INTERVAL d_value d_type ) //在date2上减去一个时间
DATEDIFF (date1 ,date2 ) //两个日期差
DAY (date ) //返回日期的天
DAYNAME (date ) //英文星期
DAYOFWEEK (date ) //星期(1-7) ,1为星期天
DAYOFYEAR (date ) //一年中的第几天
EXTRACT (interval_name FROM date ) //从date中提取日期的指定部分
MAKEDATE (year ,day ) //给出年及年中的第几天,生成日期串
MAKETIME (hour ,minute ,second ) //生成时间串
MONTHNAME (date ) //英文月份名
NOW ( ) //当前时间
SEC_TO_TIME (seconds ) //秒数转成时间
STR_TO_DATE (string ,format ) //字串转成时间,以format格式显示
TIMEDIFF (datetime1 ,datetime2 ) //两个时间差
TIME_TO_SEC (time ) //时间转秒数]
WEEK (date_time [,start_of_week ]) //第几周
YEAR (datetime ) //年份
DAYOFMONTH(datetime) //月的第几天
HOUR(datetime) //小时
LAST_DAY(date) //date的月的最后日期
MICROSECOND(datetime) //微秒
MONTH(datetime) //月
MINUTE(datetime) //分

附:可用在INTERVAL中的类型
DAY ,DAY_HOUR ,DAY_MINUTE ,DAY_SECOND ,HOUR ,HOUR_MINUTE ,HOUR_SECOND ,MINUTE ,MINUTE_SECOND,MONTH ,SECOND ,YEAR

再说一个小技巧：
比如想要在存储过程中使用"show tables";
可以使用

" SELECT `table_name` FROM `information_schema`.`TABLES`  WHERE `TABLE_SCHEMA`= 'banksys'"

替换。因为show tables 的结果并不能像select的结果这样循环。