如何在 python 中将一个变量作为另一个变量传递给 function

Question

I have a SQL variable mem_dep When I am using it directly in variable sql then it is working absolutely fine. It is printing proper SQL statement but when I am passing another variable cat in variable sql with the value " mem_dep " then it is not working fine. It is just printing value of cat

mem_dep = """SELECT * FROM TABLE1 WHERE DT2_BUSINESS = '{Business_date}'"""
cob = "20223456"
cat = "mem_dep"

Below code is working absolutely fine

def calc():
    sql = mem_dep.format(Business_date = cob)
    print(sql)

Output:

calc() # calling function
SELECT * FROM TABLE1 WHERE DT2_BUSINESS = '20223456' # printing sql

But below code is not working if I am passing variable cat in a function with the same value as variable name mem_dep

def calc(cat):
    sql = cat.format(Business_date = cob)
    print(sql)

Output:

calc(cat) # calling function
mem_dep #printing sql

How can I pass SQL variable as a variable in the function in this case?

I tried below code also but not working

def calc(cat):
    tmp_sql = "{}".format(cat)
    sql = tmp_sql.format(Business_date = cob)
    print(sql)

Output:

calc(cat) # calling function
mem_dep #printing sql

Expected output:

SELECT * FROM TABLE1 WHERE DT2_BUSINESS = '20223456' # printing sql

Answer 1

Thanks!!! I got it resolved by using eval(cat)

answer would be

sql = eval(cat).format(Business_date = cob)

Answer 2

for this output

SELECT * FROM TABLE1 WHERE DT2_BUSINESS = '20223456'

You have to give mem_dep as an argument in the calc()

calc(mem_dep)

Answer 3

From what I understand cat has the name of the SQL variable which contains your SQL string. And you want to access the SQL string from cat without knowing the value of cat . You can use getattr for this purpose and wrap everything in a class like below:

class SQLCalc:
    def __init__(self):
        self.mem_dep = """SELECT * FROM TABLE1 WHERE DT2_BUSINESS = '{Business_date}'"""
        self.cob = "20223456"
        self.cat = "mem_dep"

    def calc(self):
        sql = getattr(self, self.cat).format(Business_date = self.cob)
        print(sql)

sql_calc = SQLCalc()
sql_calc.calc()

Answer 4

Maybe like this:

mem_dep = """SELECT * FROM TABLE1 WHERE DT2_BUSINESS = '{Business_date}'"""
cob = "20223456" 

def calc(sql_template, buisness_date): 
    return sql_template.format(Business_date = buisness_date)
    
mem_dep_result = calc(mem_dep, cob)
print(mem_dep_result)