错误：sqlalchemy.exc.ProgrammingError中“ N”或附近的语法错误

Question

I have a query as

query = '''
EXECUTE sp_executesql
N'select ex.b_id, b.code, 
    b.status as status, 
    ex.c_id, c.c_no, c.title as title,
    ex.s_id, s.s_no, s.title as s_title,
    ex.o_id, isnull(o.o_no, o._id) as o_no,
    ex.e_id, 
    ex.types
  from dbo.exercises ex
    left join XXXX o on
      (ex.b_id = o.b_id and ex.c_id = o.c_id
       and ex.s_id = o.s_id and ex.o_id = o.o_id)
    inner join YYYY b on (ex.b_id = b.b_id)
    inner join ZZZZ c on (ex.b_id = c.b_id and
      ex.c_id = c.c_id)
    inner join SSSS s on (ex.b_id = s.b_id and
      ex.c_id = s.c_id and ex.s_id = s.s_id)
  where
    -- cleaning criteria
    -- interesting data selection
    ex.b_id = @bid
  order by ex.b_id, ex.c_id, ex.s_id, ex.o_id,
    ex.o_no, ex.e_id',
N'@bid int',
@bid = ?;
'''

By using pandas read_sql , fetching data from databaase.

from sqlalchemy import create_engine 
from sqlalchemy import event 
import pandas as pd 
pd.read_sql(query, conn, params=params, chunksize=None)

It throws an error as sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) syntax error at or near "N" N'select ex.b_id, b.code, ..

Answer 1

If you read the documentation , you will see that there are no string constants of the form N'...' in PostgresSQL. All string constants have the same encoding, which is specified by the setting of client_encoding for your session.