Python 动态列名称和值的字符串替换

Question

我有以下查询从 PostgreSQL 检索数据。

select_stmt = "SELECT * FROM kart_user WHERE token = %(token)s"
cursor.execute(select_stmt, { 'token': 2 })

某些案例字典可能包含多个键和值
例如-

{ 'token': 10,'custid':100,cycle:"yes" }

在这种情况下，我如何动态指定列名及其值？？

我试过了..

select_stmt = "SELECT * FROM kart_user WHERE dist.keys() = %(dist.keys())s"
cursor.execute(select_stmt, dist)

但运气不好。感谢您的回复..

Answer 1

根据您尝试过的语句，我假设您有三个键和三个值，因此您想对所有三个键一一执行 SELECT 语句。以下解决方案将对您有所帮助。

d = { 'token': 10,'custid':100,cycle:"yes" }
select_stmt = "SELECT * FROM kart_user WHERE {key} = '{value}'"
allowed_col = ['token', 'custid'] # Predefined column names to allow from coming dictionary.
for key, value in d.iteritems():
    if  key in allowed_col:
        select_stmt = select_stmt.format(key=key, value=value)
        cursor.execute(select_stmt, dist)
        # Further fetching code you can execute. Here you will get select statement for particular key and value.

@对于和条件

d = { 'token': 10,'custid':100,'cycle':"yes" }
select_stmt = "SELECT * FROM kart_user WHERE"
allowed_col = ['token', 'custid'] # Predefined column names to allow from coming dictionary.
for key, value in d.iteritems():
    if  key in allowed_col:
        condition = "{key} = '{value}'".format(key=key, value=value)
        select_stmt = select_stmt + " and " + condition
cursor.execute(select_stmt, dist)
# Further fetching code you can execute. Here you will get select statement for particular key and value.

上述答案的一个线性解决方案，

d = { 'token': 10,'custid':100,'cycle':"yes" }
condition = ' and '.join([key+'="'+str(value)+'"' for key,value in d.iteritems() if key in allowed_col])
select_stmt = "SELECT * FROM kart_user WHERE"
select_stmt = " ".join([select_stmt, condition])
cursor.execute(select_stmt, dist)
# Further fetching code you can execute. Here you will get select statement for particular key and value.

如果您的查询与我回答的不同，请回复此问题。谢谢

Python 动态列名称和值的字符串替换

Python string substitution for dynamic column name and values

python

database

postgresql

psql