Fix the issue of parameter concatenation when generating ORM with ins…

[floodpillar]

Before fixing the parameter concatenation:
d_price =
fields.DecimalField(max_digits=10, decimal_places=2null=True, )
p_price =
fields.DecimalField(max_digits=10, decimal_places=2null=True, )

After fixing the parameter concatenation:
d_price =
fields.DecimalField(max_digits=10, decimal_places=2, null=True, )
p_price =
fields.DecimalField(max_digits=10, decimal_places=2, null=True, )

[waketzheng]

Line 33: if self.data_type in ["decimal", "numeric"]:
Can be changed to elif self.data_type in ("decimal", "numeric"):

And line 39: length = ", ".join(length_parts)+", "
Shoud be changed to:

if length_parts:
    length = ", ".join(length_parts) + ", "