mysql使用from与join两表查询的区别总结

CREATE TABLE `one` (
 `id` int(0) NOT NULL AUTO_INCREMENT,
 `one` varchar(100) NOT NULL,
 PRIMARY KEY (`id`)
) ENGINE = InnoDB CHARACTER SET = utf8;

CREATE TABLE `two` (
 `id` int(0) NOT NULL AUTO_INCREMENT,
 `two` varchar(100) NOT NULL,
 PRIMARY KEY (`id`)
) ENGINE = InnoDB CHARACTER SET = utf8;

select one.id,one.one,two.id,two.two from one,two where one.id=two.id;

select one.id,one.one,two.id,two.two from one join two on one.id=two.id;

import pymysql

db = pymysql.connect("127.0.0.1", 'root', "123456", "bruce")
cursor = db.cursor()

sql = "INSERT INTO one (one) values (%s)"
for i in range(1000000):
 cursor.executemany(sql, ['one' + str(i)])
 if i % 10000 == 0:
 db.commit()
 print(str(i) + '次 commit')
db.commit()

print('insert one ok')
sql2 = "INSERT INTO two (two) values (%s)"
for i in range(100000):
 cursor.executemany(sql2, ['two' + str(i)])
 if i % 10000 == 0:
 db.commit()
 print(str(i) + '次 commit')
db.commit()
print('insert two ok')

select one.id,one.one,two.id,two.two from one,two where one.id=two.id;

select one.id,one.one,two.id,two.two from one join two on one.id=two.id;