mysqlのいくつかの添削は調べます

--        

USE test;

--       ,   mydab

CREATE DATABASE mydab;

--      

DROP DATABASE mydab;

--    

CREATE TABLE t_mytable(



-- primary key    ，      ，    

-- AUTO_INCREMENT     ，       

 id INT PRIMARY KEY AUTO_INCREMENT,

 userName VARCHAR(20),

 sex VARCHAR(2),

 birthday DATE,

 phone VARCHAR(11)

)DEFAULT CHARSET=utf8;--     

--    

DROP TABLE t_mytable;

--     

INSERT INTO t_mytable(userName,sex,birthday,phone) VALUES('  ',' ','1990-05-33','15775108922');

--   

SELECT * FROM t_mytable;

--     

ALTER TABLE t_mytable ADD edu VARCHAR(10);

--     

 ALTER TABLE t_mytable CHANGE edu edu VARCHAR(20);

 --     

 ALTER TABLE t_mytable DROP COLUMN edu;

 -- timestamp       

 ALTER TABLE t_mytable ADD entertime TIMESTAMP;

 INSERT INTO t_mytable(userName,sex,birthday,phone) VALUES('  ',' ','1992-12-22','13409871234');

 -- default    edu   

 ALTER TABLE t_mytable ADD edu VARCHAR(20) DEFAULT '  ';

 INSERT INTO t_mytable(userName,sex,birthday,phone,edu) VALUES('   ',' ','1990-12-22','13409891234','  ');

INSERT INTO t_mytable(userName,sex,birthday,phone,edu) VALUES('   ',' ','1990-12-22','13409891234','  ');

--     ,          ，      ，      ；



CREATE INDEX index_name ON t_mytable(userName);

--     

ALTER TABLE t_mytable DROP INDEX index_name

--  wife    ;

ALTER TABLE t_mytable ADD wife VARCHAR(20) UNIQUE;

--     

UPDATE t_mytable SET wife='   ' WHERE id=1;

UPDATE t_mytable SET wife='   ' WHERE id=3;

ALTER TABLE t_mytable CHANGE edu edu VARCHAR(20) DEFAULT '  ' NOT NULL;

INSERT INTO t_mytable(userName,sex,birthday,phone) VALUES('   ',' ','1990-12-22','13409891234');





CREATE TABLE t_room(

id INT PRIMARY KEY AUTO_INCREMENT,

address VARCHAR(20),

price INT,

manId INT--    ，        ，            



)DEFAULT CHARSET=utf8;

-- ADD CONSTRAINT fk_1          ，FK_1      

-- FOREIGN KEY(manId)             

-- t_room  manId     t_mytable     

ALTER TABLE t_room ADD CONSTRAINT fk_1 FOREIGN KEY(manId) REFERENCES t_mytable(id);

--       

ALTER TABLE t_room DROP FOREIGN KEY fk_1;

DROP TABLE t_room;

INSERT INTO t_room(address,price,manId) VALUES('   3 ','500000',2);