MySQL exercise 2

insert into goods values(
  ' Schoolbag ',
  18.91,
  101,
  NULL
);

insert into book values(
  'Java The core technology ',
  'Cay S. Horstman',
  56.43,
  ' Computer technology '
);

CD The question is actually asking, and the second character is A Which is the most important , Strictly speaking, only C Yes , But the question plane does not explain the verification rules . In general , The default verification rule is utf8_general_ci. In this situation ,D Also on the .

First , Let's create a system composed of 100 A table of records

delimiter //
drop procedure if exists test; # If there is test Stored procedures are deleted 
create procedure test() # Create a parameterless stored procedure , The name is test
begin
  declare i int; # Declare variables 
  set i = 1;
  while i <= 100 do # Conditions for ending the cycle : When i Greater than 100 Jump out of the loop 
    INSERT INTO test values(i);
    set i = i + 1; # Cycle time ,i Add 1
  end while; # end while loop 
  select * from test; # see test Table data 
END
// # End definition statement 


CALL test(); # End definition statement 
DELIMITER ; # Reset the separator to ;

It turns out that :1-50,70
The logic required is ：[1,50] or ((25 or 70 or 95) And [25,75]), Only 25 and 70 Satisfy , The options are not , The first half 1~50 All satisfied with , Only A Option 30 In this range , It would be A 了 .

update goods set price = price+50 where inventory > 30;

.

delete from goods where price>60 or inventory<200;

select name,age from student where name =' Zhang %' and age between 18 and 25;

select * from article where create_date between '2019-01-01 10:30:00' and '2019-11-10 16:02:00';

select * from article where title is null or create_date > '2019-01-01 00:00:00';

select * from book where author is not null or (price >50 and publish_date>'2019-01-01 00:00:00');

select * from user where (ID between 1 and 200 or between 300 and 500)
and account IS NOT NULL OR amount>1000;

Conditions 1 Two between…and… Yes or relationship , Follow “accout Column is not empty ” This condition is and related . Conditions 1 And conditions 2 Yes or relationship .