MySQL - delete data in database tables

Delete the data in the database table

• Deleting data records is a common operation in data operations , You can delete existing data records in the table . stay MySQL Through DELETE Statement to delete data records , The SQL Statements can be used in the following ways ： Delete specific data records 、 Delete all data records .

 
 
1. Delete specific data records

• stay MySQL You can delete specific data records through SQL sentence DELETE To achieve , Its grammatical form is as follows ：

  DELETE FROM tablename WHERE CONDITION;    
  

• In the above statement , Parameters tablename Indicates the table name of the data record to be deleted , Parameters CONDITION Specify to delete specific data records that meet the conditions .

  mysql> create table class(id int, name varchar(64));
  mysql> insert into class values(1, ' Zhang San ');
  mysql> insert into class values(2, ' Li Si ');
  mysql> delete from class where id=1;		// Delete... From the table id by 1 The record of 
  mysql> delete from class where name=' Li Si ';	// Delete... From the table name by ' Li Si ' The record of  
  mysql> select * from class;
  

 
 
2. Delete all data records

• stay MySQL You can also delete all data records in SQL sentence DELETE To achieve , Its grammatical form is as follows ：

  DELETE FROM tablename WHERE CONDITION;           or 
  DELETE FROM tablename;
  

• In the above statement , To delete all data records , Parameters CONDITION Need to meet table tablename All data records in , Such as id>0; Or no keywords WHERE sentence .

  mysql> create table class(id int, name varchar(64));
  mysql> insert into class values(1, ' Zhang San ');
  mysql> insert into class values(2, ' Li Si ');
  mysql> delete from class;		// Delete all records in the table 
  mysql> select * from class;