Call MySQL stored procedure using cursor.callproc() in python

Question

When I was trying to call the MySQL stored procedure using cursor.callproc() I encountered some problems. When there were multiple input and output parameters, there was no problem and everything works fine as following: I created procedure in MySQL like this with 5 input/output parameters:

create procedure enrollclass(in yeartime int, in quartertime char(20), in stid char(20), in course_no char(20), out result int)

and call procedure in python using something like this:

arg2 = ('2016', 'Q2', info[0][0], course_no, 0)
ac = cursor.callproc('enrollclass',arg2)

this worked fine. However, if I called another procedure with only one input parameter (with no output parameter) like this:

create procedure prerequisite( in course_no char(20))

and called the procedure using this line:

  arg3 = ('INFO1101')
  cursor.callproc('prerequisite', arg3)

then the system kept giving me error message 'args must be a sequence'. I have no idea how to fix it since I have no other argument to form a sequence. Could someone tell me what's going on here? Thanks!

when creating args, instead of round brackets ( ) user square brackets [ ] and it should work. — Aleksandar Varicak
– Aleksandar Varicak, Commented Nov 8, 2017 at 9:38

Gord Thompson · Accepted Answer · 2017-11-08 15:15:30Z

3

You might think that

arg3 = ('INFO1101')

would create a tuple containing a single element, but it doesn't. In that context the parentheses act as "order of operations" specifiers, e.g.

foo = (2 + 1) * 4

To create a single-element tuple you need to add a comma, as in

arg3 = ('INFO1101',)

answered Nov 8, 2017 at 15:15

Gord Thompson

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