mysql 修改表的详细语法介绍
ALTER [IGNORE] TABLE tbl_name
[alter_specification [, alter_specification] ...]
[partition_options]
algorithm_option:
ALGORITHM [=] {DEFAULT|INPLACE|COPY}
lock_option:
LOCK [=] {DEFAULT|NONE|SHARED|EXCLUSIVE}
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
| ALGORITHM [=] {DEFAULT|INPLACE|COPY}
| ALTER [COLUMN] col_name {SET DEFAULT literal | DROP DEFAULT}
| CHANGE [COLUMN] old_col_name new_col_name column_definition
[FIRST|AFTER col_name]
| LOCK [=] {DEFAULT|NONE|SHARED|EXCLUSIVE}
| 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
| RENAME {INDEX|KEY} old_index_name TO new_index_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
| DISCARD PARTITION {partition_names | ALL} TABLESPACE
| IMPORT PARTITION {partition_names | ALL} TABLESPACE
| TRUNCATE PARTITION {partition_names | ALL}
| COALESCE PARTITION number
| REORGANIZE PARTITION partition_names INTO (partition_definitions)
| EXCHANGE PARTITION partition_name WITH TABLE tbl_name [{WITH|WITHOUT} VALIDATION]
| 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}
| REMOVE PARTITIONING
常用的操作的例子：
1、修改列名，列类型，列名： 下面语句将列名为old_column的列名修改成new_column，并且数据类型为int
>alter table tablename change old_column new_column int ;
2、修改列的数据类型：将column_name 这个列的数据类型修改成为new_datatype
>alter table tablename modify column_name new_datatype ;
3、添加字段
>alter table tablename add column_name column_datatype ;
4、删除主键
>alter table tablename DROP PRIMARY KEY
5、删除分区
>alter table tablename DROP PARTITION partition_names
6、删除索引
>alter table tablename DROP INDEX index_name
7、删除列
>alter table tablename DROP col_name