MySQL alter command, mysqlalter

MySQL alter command, mysqlalter

Use the alter command in mysql to edit the table structure. The details are as follows:

Modify Field Type

mysql> alter table employee change depno depno int(5) not null;

Add Index

Mysql> alter table name add index name (field name 1 [, field name 2…]);

Example:

mysql> alter table employee add index emp_name (name);

Index with primary keywords

Mysql> alter table name add primary key (field name );

Example:

mysql> alter table employee add primary key(id);

Add an index with unique conditions

Mysql> alter table name add unique index name (field name );

Example:

mysql> alter table employee add unique emp_name2(cardnumber);

View the index of a table

Mysql> show index from table name;

Example:

mysql> show index from employee;

Delete An index

Mysql> alter table Name drop index name;

Example:

mysql>alter table employee drop index emp_name;

Modify Table: add field:

mysql> ALTER TABLE table_name ADD field_name field_type;

View table:

mysql> SELECT * FROM table_name;

Modify the original field name and type:

mysql> ALTER TABLE table_name CHANGE old_field_name new_field_name field_type;

Delete field:

ALTER TABLE table_name DROP field_name

The above is all the content of this article. I hope it will be helpful for your learning and support for helping customers.

Finally, I wish you a successful pass of the Computer Grade examination.