Some sentences commonly used in mysql
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Create a tabl
Create TABLE emp (
Id INT (10) unsigned NOT NULL AUTO_INCREMENT
Emp_no VARCHAR (10) NOT NULL
Emp_name VARCHAR (50) NOT NULL
Emp_sex CHAR (1) default null
Emp_salary DOUBLE (10dint 2) default NULL
Birthday Date default null
Entry_date TIMESTAMP (8)
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
Insert data
Insert into emp (emp_no,emp_name,emp_sex,emp_salary,birthday) values ('1001, 2004-09-23')
Add table field number after cityId
Alter table emp ADD number INT (10) after emp_name
Modify the field name definition of the table
Alter table emp change emp_name emp_namedd VARCHAR (55)
Modify the definition location of the fields of the table
Alter table emp modify emp_name VARCHAR (20) default 'zhangsan'
Delete fields from a table
Alter table emp drop emp_name
Delete tabl
Drop table emp
Clear the table data
Truncate table emp
Get the table structure
Desc emp
This is used to optimize the table. This command merges the fragments in the table and eliminates the waste of space caused by deletions or updates. This command only works on MyISAM BDB,InnoDB.
OPTIMIZE TABLE emp
Creation process: insert 10000 pieces of data into table emp
Create PROCEDURE createEmpData ()
BEGIN
Set @ Xero1
Loop1:LOOP
Set @ x = @ x + 1
If @ x = 10000 THEN
LEAVE loop1
End IF
Insert into emp (emp_no,emp_name,emp_sex,emp_salary,birthday) values ('1001, 2004, 09, 23, 2004)
End loop loop1
END
Calling procedure
Call createEmpData
Delete process
Drop PROCEDURE createEmpData
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