Linux Learning notes: MySQL Modify table structure

mysql> help alter tablename:  ' alter table ' description:syntax:alter [online  | OFFLINE] [IGNORE] TABLE tbl_name    [alter_specification  [,  alter_specification]  ...]     [partition_options]alter_specification:    table_options   | ADD [COLUMN] col_name column_definition         [FIRST | AFTER col_name ]  | ADD [COLUMN]  (col_name  Column_definition,...)   | add {index| key} [index_name]        [index_type]  (Index_col_name,...)  [index_option] ...  | add [constraint [symbol]] primary key         [index_type]  (Index_col_name,...)  [index_option] ...  | add [constraiNt [symbol]]        unique [index| key] [index_name]        [index_type]  (Index_col_name,...)  [index_option] ...  | add fulltext [index| key] [index_name]         (Index_col_name,...)  [index_option] ...  | add spatial [index| key] [index_name]         (Index_col_name,...)  [index_option] ...  | ADD [CONSTRAINT [symbol]]         FOREIGN KEY [index_name]  (Index_col_name,...)         reference_definition  | alter [column]  col_name {set default literal | drop default}  | change  [column] old_col_name new_col_name column_definitIon        [first| after col_name]  | modify [column] col_name column_definition         [first | after col_name]  | drop [ Column] col_name  | drop primary key  | drop {index| Key} index_name  | drop foreign key fk_symbol  | disable  KEYS  | ENABLE KEYS  | RENAME [TO|AS] new_tbl_name   | order by col_name [, col_name] ...  | convert to  character set charset_name [collate collation_name]  | [default]  character set [=] charset_name [collate [=] collation_name]  |  discard tablespace  | import tablespace  | force  | add partition  (partition_definition)   | DROP PARTITION  partition_names  | truncate partition {partition_names | all}  |  coalesce partition number  | reorganize partition [partition_names  INTO  (partition_definitions)]  | analyze partition {partition_names |  ALL}  | CHECK PARTITION {partition_names | ALL}  |  optimize partition {partition_names | all}  | rebuild partition { Partition_names | all}  | repair partition {partition_names | all }  | partition by partitioning_expression  | remove  partitioningindex_col_name:    col_name [(length)] [asc | desc]index_ Type:    using {btree | hash}index_option:    key_block_size [=] value   | index_type  | WITH PARSER parser_name  | COMMENT  ' String ' table_options:    table_option [[,] table_option] ...   ( see create table options) partition_options:     (See CREATE TABLE  options)

For example, use mydb data to add sex, age, and QQ columns to the student table

mysql> use mydbdatabase changedmysql> alter table student add  ' Sex '  varchar (1), add  ' Age '  tinyint (3)  unsigned, add  ' QQ '  int (Ten)   unsigned;mysql> desc student;+-------+---------------------+------+-----+---------+-------------- --+| field | type                 | Null | Key | Default | Extra           |+-------+---------------------+------+-----+---------+----------------+|  id    | int (one)               | no   | pri | null    | auto_ increment | |  name  | varchar (         | no &) nbsp; | mul | null    |                 | |  score | int (1)                | yes  |     | 0       |                 | |  sex   | varchar (1)           |  YES  |     | NULL    |                 | |  age   | tinyint (3)  unsigned | YES  |      | NULL    |                  | |  qq    | int (Ten)  unsigned    | yes  |      | NULL    |                 |+-------+---------------------+------+-----+---------+ + ---------------+6 rows in set  (0.04 SEC)

About adding more than one column at a time, see MySQL official help is not written clearly, in front of each new column need to use the keyword add, and MySQL is no number field type, to use non-negative type, you need to add the unsigned keyword after shaping.

Linux Learning notes: MySQL Modify table structure