Statement for modifying fields in mysql

The SQL statements described below are common statements used to modify fields in mysql. If you are a new user who just came into contact with the mysql database, take a look, it is helpful for you to learn how to modify mysql fields.

Modify the default value of a field in mysql

 
 

  
  
alter table tb_mer_team_column drop constraint DF_tb_mer_team_column_columnOrder  
  
  
alter table tb_mer_team_column add constraint DF_tb_mer_team_column_columnOrder default 0 for columnOrder 
 
 

Add fields in SQL statements

 
 

  
  
Alter table table1 (table Name) add No_id (field name) char (12) (Field Type) t null | null UNIQUE after 'characters' added after the specified field
 
 

Modify the field type in mysql

 
 

  
  
Alter table t1 (table Name) alter column a (field name) text (50) (field type)
 
 

Add a primary key field in SQL

 
 

  
  
alter table tb_mer_basInfo add constraint [PK_tb_merchantBasInfo] primary key ( merchantID) 
 
 

SQL deletes a table Field

 
 

  
  
alter table `lm_aclass` drop 'cpid' 
 
 

 

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