python - 如何解决Python错误 "not all arguments converted while string formatting"

Question

当我执行下面的程序时

import MySQLdb
cn = MySQLdb.connect(host="localhost", user="root", passwd="mysqlroot", 
db="sv_data")
cursor = cn.cursor()
cursor.execute("select addressline1, zipcode from sv_address where zipcode = '10011'")
for (addressline1, zipcode) in cursor:
print(addressline1, zipcode)
cursor.close()
cn.close()

效果很好。但是，当我尝试在查询中添加参数时，如下所示

import MySQLdb
 cn = MySQLdb.connect(host="localhost", user="root", passwd="****",     
db="sv_data")
cursor = cn.cursor()

a="10011"
cursor.execute("select addressline1, zipcode from sv_address where zipcode = 
%s", (a))
for (addressline1, zipcode) in cursor:
 print(addressline1, zipcode)

cursor.close()
cn.close()

出现错误ProgrammingError:在字符串格式化过程中并非所有参数都被转换

您能告诉我如何解决这个问题吗？我尝试了各种选择。 zipcode 是 mysqldb 中的 varchar 字段

Answer 1

您没有传递参数。你宁愿给它一个字符串。

试试这个。

cursor.execute("select addressline1, zipcode from sv_address where zipcode = %s" % a )

最好的方法是将参数和 sql_query 分开

_sql = "select addressline1, zipcode from sv_address where zipcode = {0}"
cursor.execute(_sql.format(a))