比较运算符

57.8 比较运算符

= 等于,!= 或 <> 不等于,> >= < <= 大小比较。

比较 NULL 必须用 IS NULL,写 =NULL 结果不对。

分数段筛选

import pymysql

conn = pymysql.connect(host='127.0.0.1', user='root', password='root', database='py_demo', charset='utf8mb4')
try:
    with conn.cursor() as cur:
        cur.execute('SELECT name, score FROM students WHERE score >= %s', (90,))
        print('90分及以上:', cur.fetchall())
        cur.execute('SELECT name, score FROM students WHERE score <> %s', (60,))
        print('不是60分的:', cur.fetchall())
finally:
    conn.close()