将列表转换为要在 Pandas dataframe 查询的 IN 子句中替换的逗号分隔整数

Question

I have a list of integers that contains EMPI_ID

emp_list = [1,2]

I have a variable that defines the SQL query

emp_sql = '''
select 
      emp_id
    , emp_name
from emp
where emp in (%s)
'''

Columns for the dataframe:

emp_columns = [emp_id, emp_name]

When I try to convert them to comma separated integer values, the sql_string hold Str values and is failing to fetch the data from database.

emp = ','.join(emp_list)
sql_string = emp_sql%(emp)    
data = connection.fetchall(sql_string) 
df = pd.DataFrame.from_records(data, columns=emp_columns)

Please advise how i can change the query to substitute the IN clause of SQL with list of integers. from_records does not have param as parameter to pass the joined sql string.

Answer 1

list comprehension is you friend

emp_sql = f'''
select 
      emp_id
    , emp_name
from emp
where emp in (%s)
'''%(", ".join([str(i) for i in emp_list]))

print(emp_sql)

output:

select 
      emp_id
    , emp_name
from emp
where emp in (1, 2)

join only works with str , so you have to convert the elements in the list, thats where you can use list comprehension. With the join, you can enter them into the query.

EDIT: if you want the numbers quoted, try this

emp_sql = f'''
select 
      emp_id
    , emp_name
from emp
where emp in (%s)
'''%(", ".join([f"'{i}'" for i in emp_list]))

print(emp_sql)

giving this output:

select 
      emp_id
    , emp_name
from emp
where emp in ('1', '2')