MySQL Query statement

Select field 1, Field 2 from Table 1, table 2 where field group by Group Field having field order by field asc| DESC Limit M,n

First, to inquire all

Select *  from student;

Select  as  from student;

Select  from student;

Second, the conditions of inquiry

1. Query student ID equals 1

*  from where student_id;

2. Query the Name field NULL

*  from where  is null;

3. Query the name field is not NULL

Select *  from where  is  not null;

4. Query the Name field is an empty string

Select *  from where = ";

5. Query the Name field is not an empty string and is not NULL

Select *  from where != ";

6. Query the city character Gencun data in Henan province and Shandong Province

Select *  from where inch (' Shandong province ',' Henan province ');

7. Query age from 25 to 30

Select *  from where between  -  and ;

8. Query that age is not between 20 and 30

Select *  from where  not between  -  and ;

9. Query the first word is Guo's data

Select *  from where  like ' Guo% ';

10 Query The first word is Guo's two characters of data

Select *  from where  like ' Guo _ ';

11 Query the existence of Guo's Word data

Select *  from where  like ' % Guo ';

Third, group query

1. Group Sex

Select Sex,count(*fromgroup by sex;

2. Group sex Pre-condition query

Select Sex,count(*fromwhere!=' Li Bai  'group by sex;

3. Group Sex after conditional query

Select Sex,count(*fromgroupby hascount (*)>5;

4. Group after query and then condition query

Select Sex,count(*fromwhere!=' li Bai '  Groupby hascount(*)>5;

Four, sort query

1. Descending sort

Select *  from Order  by desc;

2. Descending and Ascending sort

Select *  from Order  by desc ASC;

Five, aggregate function

Count (*) sum (Salary) avg (Salary) min (Salary) Max (Salary)

MySQL Query statement