DatabaseError: The first argument to execute must be a string or unicode query in python

Question

I am trying to return a date selected from date picker in to my sql query in my python code. I also tried using encode(utf-8) to remove the unicode string but still, I am getting the error.

I am new to python. Can anyone please help me figure out how to solve this problem? I am using python flask to create the webpage

if request.method=='POST':
        dateval2 = request.form['datepick']
        dateval = dateval2.encode('utf-8')
    result = ("SELECT * FROM OE_TAT where convert(date,Time_IST)='?'",dateval
    df = pd.read_sql_query(result,connection)`

Error:

pandas.io.sql.DatabaseError
DatabaseError: Execution failed on sql '("SELECT * FROM OE_TAT where convert(date,Time_IST)='?'", '2015-06-01')': The first argument to execute must be a string or unicode query.

Answer 1

You are providing a tuple to read_sql_query, while the first argument (the query) has to be a string. That's why it gives the error "The first argument to execute must be a string or unicode query".

You can pass the parameter like this:

result = "SELECT * FROM OE_TAT where convert(date,Time_IST)=?"
df = pd.read_sql_query(result, connection, params=(dateval,))

Note that the use of ? depends on the driver you are using (there are different ways to specify parameters, see https://www.python.org/dev/peps/pep-0249/#paramstyle). It is possible you will have to use %s instead of ?.

You could also format the string in beforehand, like result = "SELECT * FROM OE_TAT where convert(date,Time_IST)={0}".format(dateval), however, this is not recommended, see eg here