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This article mainly explains "what you need to pay attention to and what are the common table changes in PHP?" friends who are interested may wish to have a look. The method introduced in this paper is simple, fast and practical. Next, let the editor take you to learn "what you need to pay attention to in modifying tables in PHP and what are common table changes?"

Modify the table

The following points are explained:

1. Modifying a table refers to modifying the structure of the table-just as creating a table is also setting the structure of the table.

2. You can do almost everything you can do to create a table-but it is not recommended to modify the table, but you should basically determine the structure of the table when you create the table.

3, generally speaking, yes

3.1 Fields can be added, deleted, and modified

3.2 you can add and delete the index.

4, table options are usually "modified", even if they do not write any table options, they all have their default values.

Several common ones:

Add field: alter table table name add [column] New field name field type [field attribute list]

Modified field: (and can be renamed): alter table table name change [column] Old field name new field name new field type [new field property list]

Delete the field. Alter table table name drop [column] field name

Add a normal index: alter table table name addkey [index name] (field name 1 [, field name 2.]) Add unique index (constraint): alter table table name add unique key (field name 1 [, field name 2.]) Add primary key index (constraint): alter table table name add primary key (field name 1 [, field name 2.]):

Modify table name: alter table old table name

Rename [to] New Table name

# the following shows how to modify the table:

Alter table tab_xuanxiang add column email varchar (50); alter table tab_xuanxiang add key (age); / * add a general index * / so far, I believe you have a deeper understanding of "what you need to pay attention to in modifying tables in PHP and what common modified tables are". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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