mysql小白之旅——基础篇2——表和视图的增删改

1.CREATE TABLE Statement（创建表语句）

参考：https://www.techonthenet.com/mysql/tables/create_table.php

（简单形式）

CREATE TABLE table_name
( 
  column1 datatype [ NULL | NOT NULL ],
  column2 datatype [ NULL | NOT NULL ],
  ...
);

（完整形式）

CREATE [ TEMPORARY ] TABLE [IF NOT EXISTS] table_name
( 
  column1 datatype [ NULL | NOT NULL ]
                   [ DEFAULT default_value ]
                   [ AUTO_INCREMENT ]
                   [ UNIQUE KEY | PRIMARY KEY ]
                   [ COMMENT 'string' ],

  column2 datatype [ NULL | NOT NULL ]
                   [ DEFAULT default_value ]
                   [ AUTO_INCREMENT ]
                   [ UNIQUE KEY | PRIMARY KEY ]
                   [ COMMENT 'string' ],
  ...

  | [CONSTRAINT [constraint_name]] PRIMARY KEY [ USING BTREE | HASH ] (index_col_name, ...)

  | [INDEX | KEY] index_name [ USING BTREE | HASH ] (index_col_name, ...)

  | [CONSTRAINT [constraint_name]] UNIQUE [ INDEX | KEY ] 
        [ index_name ] [ USING BTREE | HASH ] (index_col_name, ...)

  | {FULLTEXT | SPATIAL} [ INDEX | KEY] index_name (index_col_name, ...)

  | [CONSTRAINT [constraint_name]] 
        FOREIGN KEY index_name (index_col_name, ...)
        REFERENCES another_table_name (index_col_name, ...)
        [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
        [ ON DELETE { RESTRICT | CASCADE | SET NULL | NO ACTION } ]
        [ ON UPDATE { RESTRICT | CASCADE | SET NULL | NO ACTION } ]

  | CHECK (expression)

    {ENGINE | TYPE} = engine_name
  | AUTO_INCREMENT = value
  | AVG_ROW_LENGTH = value
  | [DEFAULT] CHARACTER SET = charset_name
  | CHECKSUM = {0 | 1}
  | [DEFAULT] COLLATE = collation_name
  | COMMENT = 'string'
  | DATA DIRECTORY = 'absolute path'
  | DELAY_KEY_WRITE = { 0 | 1 }
  | INDEX DIRECTORY = 'absolute path'
  | INSERT_METHOD = { NO | FIRST | LAST }
  | MAX_ROWS = value
  | MIN_ROWS = value
  | PACK_KEYS = {0 | 1 | DEFAULT}
  | PASSWORD = 'string'
  | RAID_TYPE = { 1 | STRIPED | RAIDO }
       RAID_CHUNKS = value
       RAID_CHUNKSIZE = value
  | ROW_FORMAT = {DEFAULT | DYNAMIC | FIXED | COMPRESSED}
  | UNION = (table1, ... )
);

PS：完整的形式有点吓人，但实际上大部分都不常用。

2.REATE TABLE AS Statement（复制形式创建表）

参考：https://www.techonthenet.com/mysql/tables/create_table_as.php

CREATE TABLE [ IF NOT EXISTS ] new_table [ AS ] 
  SELECT expressions
  FROM existing_tables
  [WHERE conditions];

PS：这种用法可以用来快速从一个有数据的表或者一个复杂的关联查询中生成一个子表，比如可以用于数据快速备份。

3.ALTER TABLE Statement（修改表语句）

参考：https://www.techonthenet.com/mysql/tables/alter_table.php

ALTER TABLE table_name
  ADD new_column_name column_definition
    [ FIRST | AFTER column_name ],
  ADD new_column_name column_definition
    [ FIRST | AFTER column_name ],
  ...
;

4.DROP TABLE Statement（删除表语句）

DROP [ TEMPORARY ] TABLE [ IF EXISTS ]
table_name1, table_name2, ...
[ RESTRICT | CASCADE ];

5.VIEW（视图）

参考：https://www.techonthenet.com/mysql/views.php

——CREATE

CREATE [OR REPLACE] VIEW view_name AS
  SELECT columns
  FROM tables
  [WHERE conditions];

——Update

ALTER VIEW view_name AS
  SELECT columns
  FROM table
  WHERE conditions;

——Drop

DROP VIEW [IF EXISTS] view_name;

PS：视图的作用也很多，比如可以用于报表查询的，也可以用来做一些数据清洗；

mysql小白之旅——基础篇2——表和视图的增删改

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