python3 +MySQLdb 遇到的问题，

aaa2520

B=2
count = cursor.execute('''select * from info where ID=%s''',(B,))


这样语句 没看出啥问题 总提示
_mysql_exceptions.ProgrammingError: (1064, "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '%s' at line 1")

为啥 ？？

askandstudy

没有这样的语法吧

1. B=2
   
2. sql="select * from info where ID=%s" % B
   
3. cursor.execute(sql)

复制代码

aaa2520

多谢，你的方法可以
难道是版本的问题？
我看的是这个
依葫芦画瓢。
http://mysql-python.sourceforge.net/MySQLdb.html#cursor-objects
The connect() method works nearly the same as with _mysql:

import MySQLdb
db=MySQLdb.connect(passwd="moonpie",db="thangs")
To perform a query, you first need a cursor, and then you can execute queries on it:

c=db.cursor()
max_price=5
c.execute("""SELECT spam, eggs, sausage FROM breakfast
          WHERE price < %s""", (max_price,))
In this example, max_price=5 Why, then, use %s in the string? Because MySQLdb will convert it to a SQL literal value, which is the string '5'. When it's finished, the query will actually say, "...WHERE price < 5".

Why the tuple? Because the DB API requires you to pass in any parameters as a sequence. Due to the design of the parser, (max_price) is interpreted as using algebraic grouping and simply as max_price and not a tuple. Adding a comma, i.e. (max_price,) forces it to make a tuple.

aaa2520

如果我想一次插入数据怎么写？
c.execute("insert into info(title,Pnum,Pnei,Pdate,puser,pid) values(%s,%s,%s,%s,%s,%s)"  % (cs[0],cs[1],cs[2],cs[3],cs[4],cs[5]))

没理解 是个啥意思。

askandstudy

你在3楼贴的原文确实是这么用的，我是用sqlite来试的，我的机器上没mysql，不好意思，等我装了mysql再试试那个用法看看

一次插入多行的例子可以这样啊，多行数据保存到一个元组列表变量中就行了。
cursor.executemany(
      """INSERT INTO breakfast (name, spam, eggs, sausage, price)
      VALUES (%s, %s, %s, %s, %s)""",
      [
      ("Spam and Sausage Lover's Plate", 5, 1, 8, 7.95 ),
      ("Not So Much Spam Plate", 3, 2, 0, 3.95 ),
      ("Don't Wany ANY SPAM! Plate", 0, 4, 3, 5.95 )
      ] )

aaa2520

sqlite 下我试验过
这样的语句 工作的挺好。
c.execute("select pid from info where pid = ?",(ppp,))


要是插入数据 包含特殊字符怎么插入到数据库中？