Mysql SQL statements Daquan

Mysql SQL statements Daquan

1, Description: Create DATABASE dbname;

2. Description: Delete database drop DB dbname;

3. Description: Creating a new Table CREATE table tabname (col1 type1 [NOT NULL] [primary key],col2 type2 [NOT NULL],..);

4. Description: Delete new table drop table tabname;

5. Description: Add a column Alter table tabname add column col type;

6, Description: A few simple basic SQL statements
selection: SELECT * from table1 where range;
insert: INSERT INTO table1 (field1,field2) values (value1,value2);
Delete: Delete from table1 where range;
Updated: Update table1 set field1=value1 where range;
Find: SELECT * FROM table1 where field1 like '%value1% '---the syntax of like is very subtle, check information!;
Sort: SELECT * FROM table1 ORDER by field1,field2 [DESC];
Total: Select count as TotalCount from table1;　　
sum: Select sum (field1) as Sumvalue from table1;
Average: Select AVG (field1) as Avgvalue from table1;
Maximum: Select Max (field1) as MaxValue from table1;
min: select min (field1) as MinValue from table1;

7, left JOIN Connect:

　　Left join: Returns all fields in the left table that match the criteria in the table to the right.　　

JOIN  on Stu.classe_name=tech.classe_name;

Here are two tables:

Table Stu

　　

Table Tech

　　

The results are as follows:

8. Internal connection:

　　Returns an entry in the table that meets the criteria.

JOIN  on Stu.classe_name=tech.classe_name;

The results are as follows:

9、右连接： returns all fields in the right table that match the criteria in the table on the left.

JOIN  on Stu.classe_name=tech.classe_name;

The results are as follows:

 

Mysql SQL statements Daquan