1, views
create:
create view as SQL statements view name (e.g. select id, name from t1 where id> 10);
modify:
alter view view name as SQL statements;
delete:
View Name drop view;
2, the trigger:
When a table will do the perception of manipulation (CRUD), trigger custom behavior
demiliter // # // to change the terminator
When create tigger t1 before insert on student for each row # t1 of the trigger named student table do insert trigger action
begin
insert into loggin(lname) values(new.sname)
insert into loggin(lname) values(new.sname)
end
NEW, new data, usually only generated when the insert update operation
OLD, old data is usually generated when the delete operation
3, function
python
def f1(a1,a2):
return a1 + a2
f1 ()
Built-in functions
Execution of the function select CURDATE ();
blog
id title ctime
1 asdf 2019-11
2 asdf 2019-11
3 asdf 2019-10
4 asdf 2019-10
select ctime,count(1) from log group by ctime;
select DATE_FORMAT(ctime,"%Y-%m") from blog group by DATE_FORMAT(ctime,"%Y-%M")；
2019-11 2
2019-10 2
Custom function (return value)
delimiter //
create function(
i1 int,
i2 int
)
begin
delcare num int default 0;
set num = i1 + i2;
return (whether);
end
delimiter ;
select f1(1,100);
4, stored procedures
An alias == "Save MySQL on some already written sql statement
Call: Alias ();
Used in place of programmers to write sql statement
method one:
MySQL: Stored Procedures
Program: call a stored procedure
1, simple
delimiter //
create procedure p1()
begin
select * from teacher;
inser into student(sname) valuer('ct');
end //
delimiter ;
call p1 (); # MySQL calls
cursor.callproc ( 'p1') # python call
2, pass the parameter (in, out, inout)
delimiter //
create procedure p2(
in n1 int,
in n2 int
)
begin
select * from teacher where tid > n1;
end //
delimiter ;
call p1 (12,2); # MySQL calls
cursor.callproc ( 'p2', (12,2)) # Python pymysql call
3, parameter out
delimiter //
create procedure p3(
in n1 int;
out n2 int
)
begin
set n2 = 123123;
select * from student where sid > n2;
end //
delimiter ;
# Mysql call effects to achieve the return of indirect variables by @ v1
set @v1 = 12;
call p3(12,@v1)
select @ v1; # p3 call after call to @V variables into them, then n2 is actually @v, set @v from 12 to reassign 123123.
# Pymysql call a stored procedure, the default mysql in the implementation of the following statements.
set @_p3_0 = 12;
set @_p3_1 = 2;
call p3(@_p3_0,@_p3_1)
select @_p3_0,@_p3_1;
cursor.callproc('p3',(12,2))
r1 = cursor.fetchal()
print(r1)
cursor.execute('select @_p3_0,@_p3_1')
r2 = cursor.fatchall()
print(r2)
The results set out why there needs return values falsified
delimiter //
create procedure p3(
From in n1 int,
Results of out n2 int procedure for identifying a stored identifier 1 is 1,2 error ERROR is normally 2
)
begin
insert into vv(..)
insert into vv(..)
insert into vv(..)
end //
delimiter ;
4, transaction
delimiter //
create procedure p4(
Out Sataus int
)
begin
1, the statement is executed if abnormal {
set status = 1;
rollback;
}
Begin transaction
--- A accounts minus 100 yuan
--- B accounts increased 80 yuan
--- C accounts increased 20 yuan
--- commit；
End
setstatus = 2；
end //
delimiter ；
----------------------------------------------
Example # Affairs
demiliter //
create PROCEDURE P5(
OUT p_return_code tinyint
)
befin
declare exit hadler for sqlexecption
begin
--- ERROR
set p_return_code = 1;
rollback;
end;
start transaction;
delete from tb1;
inser into tb2(name) values('veven');
commit;
--- success
set p_return_code =2 ;
end //
delimiter ;
----------------------------------------
5, the cursor
delimiter //
create procedure p6()
begin
declare row_id int; - Variable 1
declare row_num int; - Variable 2
declare done int DEFAULT FALSE;
declare temp int;
declare my_cursor cursor for select id,num from A;
declare continuehandler for not found set done = TRUE;
open my_cursor:
bbj:LOOP
fetch my_cursor inti row_id,row_num;
if done the
leave bbj;
end if
set temp = row_id + row_num
insert into B(number) values(temp)
end loop bbj;
close my_cursor;
end //
delimiter ;
6, the implementation of dynamic SQL (Anti-SQL injection)
delimiter //
create procedure p7(
in tpl varchar(255)
in arg int
)
begin
1, preflight car something SQL statements legitimacy
2, SQL = tp1 format
3, the implementation of sql statement
set @xo = arg;
PREPARE XXX FROM 'select * from student where sid > ?';
execute XXX using @xo; # @ variables can only be used
DEALLOCATE prepare prod;
end //
delimiter ;