【SQL篇章】【SQL语句梳理 :--基于MySQL5.6】【已梳理：ALTER TABLE解析】

CREATE TABLE t1 (a INTEGER,b CHAR(10));

ADD [COLUMN] (col_name column_definition,...)　

ALTER TABLE t1 ADD COLUMN c TIMESTAMP;

mysql> desc t1;
+-------+-----------+------+-----+-------------------+-----------------------------+
| Field | Type      | Null | Key | Default           | Extra                       |
+-------+-----------+------+-----+-------------------+-----------------------------+
| a     | int(11)   | YES  |     | NULL              |                             |
| b     | char(10)  | YES  |     | NULL              |                             |
| c     | timestamp | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+-------+-----------+------+-----+-------------------+-----------------------------+

ADD [COLUMN] col_name column_definition [FIRST | AFTER col_name ]

ALTER TABLE t1 ADD COLUMN d int after a;

mysql> desc t1;
+-------+-----------+------+-----+-------------------+-----------------------------+
| Field | Type      | Null | Key | Default           | Extra                       |
+-------+-----------+------+-----+-------------------+-----------------------------+
| a     | int(11)   | YES  |     | NULL              |                             |
| d     | int(11)   | YES  |     | NULL              |                             |
| b     | char(10)  | YES  |     | NULL              |                             |
| c     | timestamp | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+-------+-----------+------+-----+-------------------+-----------------------------+

ADD {INDEX|KEY} [index_name] [index_type] (index_col_name,...) [index_option] ...

ALTER TABLE t1 ADD INDEX idx_d(d); (d列增加索引)

CREATE TABLE `t1` (
  `a` int(11) DEFAULT NULL,
  `d` int(11) DEFAULT NULL,
  `b` char(10) DEFAULT NULL,
  `c` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  KEY `idx_d` (`d`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1

CREATE TABLE s1(id INT,NAME VARCHAR(10),address CHAR(20));
CREATE TABLE s2(id INT,s1_id INT);　

ALTER TABLE s1 ADD PRIMARY KEY(id); (列被置成not null)

mysql> desc s1;
+---------+-------------+------+-----+---------+-------+
| Field   | Type        | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| id      | int(11)     | NO   | PRI | 0       |       |
| name    | varchar(10) | YES  |     | NULL    |       |
| address | char(20)    | YES  |     | NULL    |       |
+---------+-------------+------+-----+---------+-------+　

ALTER TABLE s1 ADD UNIQUE KEY (NAME);

mysql> desc s1;
+---------+-------------+------+-----+---------+-------+
| Field   | Type        | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| id      | int(11)     | NO   | PRI | 0       |       |
| name    | varchar(10) | YES  | UNI | NULL    |       |
| address | char(20)    | YES  |     | NULL    |       |
+---------+-------------+------+-----+---------+-------+

ADD [CONSTRAINT [symbol]] FOREIGN KEY [index_name] (index_col_name,...) reference_definition

ALTER TABLE s2 ADD FOREIGN KEY (s1_id) REFERENCES s1 (id); 指向表s1的id列

CREATE TABLE `s2` (
  `id` int(11) DEFAULT NULL,
  `s1_id` int(11) DEFAULT NULL,
  KEY `s1_id` (`s1_id`),
  CONSTRAINT `s2_ibfk_1` FOREIGN KEY (`s1_id`) REFERENCES `s1` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1

ALTER TABLE t1 ADD FULLTEXT full_f (f);　

CREATE TABLE `t1` (
  `a` int(11) NOT NULL DEFAULT ‘0‘,
  `d` int(11) DEFAULT NULL,
  `b` char(10) DEFAULT NULL,
  `c` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  `f` text,
  PRIMARY KEY (`a`),
  KEY `idx_d` (`d`),
  FULLTEXT KEY `full_f` (`f`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1

ALTER [COLUMN] col_name {SET DEFAULT literal | DROP DEFAULT}　　

ALTER TABLE t1 ALTER COLUMN a SET DEFAULT ‘1‘;　　

ALTER TABLE t1 ALTER COLUMN d DROP DEFAULT ;

CREATE TABLE `t1` (
  `a` int(11) NOT NULL DEFAULT ‘1‘,
  `d` int(11),
  `b` char(10) DEFAULT NULL,
  `c` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  `f` text,
  PRIMARY KEY (`a`),
  KEY `idx_d` (`d`),
  FULLTEXT KEY `full_f` (`f`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1

CREATE TABLE t1 (a INTEGER,b CHAR(10));　

CHANGE [COLUMN] old_col_name new_col_name column_definition [FIRST|AFTER col_name]　

 ALTER TABLE t3 CHANGE a a_1 INT NOT NULL AFTER b;

MODIFY [COLUMN] col_name column_definition [FIRST | AFTER col_name]

ALTER TABLE t4 MODIFY a INT NOT NULL,CHANGE b c VARCHAR(20);

DROP [COLUMN] col_name

ALTER TABLE t1 DROP COLUMN a;

DROP PRIMARY KEY

ALTER TABLE t1 DROP PRIMARY KEY;

DROP {INDEX|KEY} index_name

ALTER TABLE t1 DROP INDEX idx_d;

DROP FOREIGN KEY fk_symbol

ALTER TABLE s2 DROP FOREIGN KEY s2_ibfk_1

CREATE TABLE `s2` (
  `id` int(11) DEFAULT NULL,
  `s1_id` int(11) DEFAULT NULL,
  KEY `s1_id` (`s1_id`),
  CONSTRAINT `s2_ibfk_1` FOREIGN KEY (`s1_id`) REFERENCES `s1` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1

RENAME [TO|AS] new_tbl_name

ALTER TABLE t1 rename to t2;

[DEFAULT] CHARACTER SET [=] charset_name [COLLATE [=] collation_name]

ALTER TABLE t1 CHARACTER SET = utf8;