Demo of using MySQL to modify table fields

The following articles mainly describe how to modify table fields in MySQL, and describe the actual operation code for modifying table fields in MySQL, if you are interested in the actual operations, you can click to view the following articles. I hope you will gain some benefits after browsing it,

Modify Table fields in MySQL:

Primary Key 549830479

 
 

  
  
alter table tabelname add new_field_id int(5) unsigned default 0 not null auto_increment ,add primary key (new_field_id); 
 
 

Add a new column 549830479

 
 

  
  
alter table t2 add d timestamp;  
  
  
alter table infos add ex tinyint not null default '0'; 
 
 

Delete column 549830479

 
 

  
  
alter table t2 drop column c; 
 
 

Rename column 549830479

 
 

  
  
alter table t1 change a b integer; 
 
 

Change column type 549830479

 
 

  
  
alter table t1 change b b bigint not null;  
  
  
alter table infos change list list tinyint not null default '0'; 
 
 

MySQL needs to rename table 549830479 in modifying table fields

 
 

  
  
alter table t1 rename t2; 
 
 

Add index 549830479

 
 

  
  
MySQL> alter table tablename change depno int (5) not null;
  
  
MySQL> alter table tablename add index name (field name 1 [, field name 2…]);
  
  
MySQL> alter table tablename add index emp_name (name );
 
 

Index with primary keyword 549830479

 
 

  
  
MySQL> alter table tablename add primary key(id); 
 
 

Add an index of 549830479 with unique restrictions

 
 

  
  
MySQL> alter table tablename add unique emp_name2(cardnumber); 
 
 

Delete An index 549830479

 
 

  
  
MySQL>alter table tablename drop index emp_name; 
 
 

Modify Table: 549830479

Add field: 549830479

 
 

  
  
MySQL> ALTER TABLE table_name ADD field_name field_type; 
 
 

Modify the original field name and type: 549830479

 
 

  
  
MySQL> ALTER TABLE table_name CHANGE old_field_name new_field_name field_type;  
 
 

Delete field: 549830479

 
 

  
  
MySQL> ALTER TABLE table_name DROP field_name; 
 
 

The above content is an introduction to modifying table fields in MySQL. I hope you will find some gains.