Python中的多字符串插值

Question

我正在嘗試構建一個SQL查詢，它涉及同一個字符串的兩個單獨插入，它本身是通過用逗號連接列表（術語）來構造的。 我這樣做如下：

format_strings = ','.join(['%s'] * len(terms))
sql = """
SELECT i.id, i.title, i.description, MATCH (i.title, i.description) AGAINST (%s IN NATURAL LANGUAGE MODE) AS score
FROM items i
WHERE MATCH (i.title, i.description) AGAINST (%s IN NATURAL LANGUAGE MODE) AS score""" % format_strings, (terms, terms)

結果是TypeError: not enough arguments for format string

這只適用於術語的一種用法，但不是一秒鍾。 我是Python的新手，所以這可能非常簡單。 任何幫助非常感謝！

編輯：術語來自在包含空格的字符串上運行.split（），因此('apples', 'oranges')將是一個示例值。

更新 ：

以下結果導致SQL錯誤，但它確實看起來像字符串沒有被替換（％s出現在SQL中）：

terms = term.split()
format_strings = ','.join(['%s'] * len(terms))
sql = """SELECT i.id, i.title, i.description, MATCH (i.title, i.description) AGAINST (%s IN NATURAL LANGUAGE MODE) AS score
FROM items i
WHERE MATCH (i.title, i.description) AGAINST (%s IN NATURAL LANGUAGE MODE)""" % (format_strings, (terms, terms))
cursor.execute(sql)

輸出：

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 IN NATURAL LANGUAGE MODE) AS score\tFROM items i\tWHERE MATCH (i.title, i.descr' at line 1")

Answer 1

在格式化查詢時，您需要傳遞format_strings兩個實例，或者更好的是，使用str.format()並引用兩次參數：

sql = """
SELECT i.id, i.title, i.description, MATCH (i.title, i.description)
  AGAINST ({0} IN NATURAL LANGUAGE MODE) AS score
FROM items i
WHERE MATCH (i.title, i.description) AGAINST ({0} IN NATURAL LANGUAGE MODE)
  AS score""".format(format_strings)

然后將參數傳遞給cursor.execute() ：

cursor.execute(sql, terms*2)

Answer 2

你可以按如下方式准備你的sql：

format_strings = ','.join(['%s'] * len(terms))
sql = """SELECT i.id, i.title, i.description, MATCH (i.title, i.description) AGAINST (%s IN NATURAL LANGUAGE MODE) AS score FROM items i WHERE MATCH (i.title, i.description) AGAINST (%s IN NATURAL LANGUAGE MODE) AS score""" % (format_strings, format_strings)
#Execute the sql in your database cursor
db_cursor.execute(sql,[terms,terms])