Introduction
Web2Py has a Python interpreter and is developed in Python. This full-stack web framework functions without issue on all popular web servers and OS systems. It supports the MVC architecture and standard web development techniques, including server-side sessions and secure processing of uploaded files, making it a popular language among developers.
Now let us dive further into this topic and understand the concept of Query, Set, and Rows in Web2py along with the help of a few examples.
Query, Set, and Rows in Web2py
Consider the table in Query, Set, and Rows in Web2py and add three records:
>>>db.define_table('mobile', Field('brand'))
<Table mobile (id, brand)>
>>> db.mobile.insert(name="Realme")
1
>>> db.mobile.insert(name="OPPO")
2
>>> db.mobile.insert(name="Apple")
3
The table can be kept in a variable. For instance, with a variable mobile, you could do the following:
>>> mobile = db.mobile
Additionally, a field, like a brand, can be stored in a variable. You could, for instance, carry out:
>>> brand = mobile.brand
You may even create a query (using operators like ==,!=,<, >, <=, >=, like, and belongs) and save it in a variable called q in Query, Set, and Rows in Web2py, as in
>>> q = name == 'Realme'
A set of records is specified when you call db with a query. You might put it in a variable called s and form:
>>> s = db(q)
In Query, Set, and Rows in Web2py, you'll notice that there hasn't yet been a database query. DAL + Query defines a set of records in this database that answers the question. Specifying which table (or tables) are involved is unnecessary because web2py infers this information from the query.
Rendering rows using represent
To use the formatting data in the represents option of the fields, you might want to rewrite the rows returned by select in Query, Set, and Rows in Web2py.
rows = db(query).select()
repr_row = rows.render(0)
A generator will loop over all the rows if you don't give an index:
for row in rows.render():
print row.myfield
Also applicable to slices:
for row in rows[0:10].render():
print row.myfield
In Query, Set, and Rows in Web2py, you can specify a list of fields in the "fields" parameter if you want to alter a subset of them via their "represent" attribute:
repr_row = row.render(0, fields=[db.mytable.myfield])
There is no update record (which you wouldn't want anyway) or delete history because it returns a transformed copy of the original row.
Fetching a Row
The following is yet another useful syntax in Query, Set, and Rows in Web2py:
record = db.mytable(id)
record = db.mytable(db.mytable.id == id)
record = db.mytable(id, myfield='somevalue')
The above approach appears safer and more versatile than db.mytable[id]. It first determines whether id is an integer (or whether str(id) is an integer) and returns None if it is not (it never raises an exception). It is also possible to define various record criteria. When they are not satisfied, it also returns None.
34+ registered 
