将 sql 存储在 python 中的变量中

Question

I need help in storing the query result in a variable after executing the select statement. this is my code below.. there are no error but i need help in storing it in a variable in PYTHON. i am using pymssql and python 2.7.9. thanks in advance

conn = pymssql.connect(host='localhost', user='xx', password='xx', database='dbpython')
    c = conn.cursor()
    row = c.execute("select fid, fname, lname, contact from tblcontact where fname='maiji'")
    row = c.fetchall()
    while row:
        print row
        row = c.fetchall()

Answer 1

Stripping down your code, this is what you're doing in short.

row = c.ex...
row = c.fe..
    row = c.fe...

In programming, this is called assigning a value to a variable. In short, row is the container and you're replacing it over and over multiple times.

We'll ignore optmizations for now and just go with the basics.

conn = pymssql.connect(host='localhost', user='xx', password='xx', database='dbpython')
c = conn.cursor()
row = c.execute("select fid, fname, lname, contact from tblcontact where fname='maiji'")
rows = c.fetchall()
for row in rows:
    print(row)

First of all, c.fetchall() retrieves ALL the results from your query, we'll put them in a variable called rows . Then we create a iterator (the thing you tried to do with the while loop) by doing for row in rows . Then we simply print each row.

How you should do it tho

This is called context managers.

with pymssql.connect(host='localhost', user='xx', password='xx', database='dbpython') as conn:
    c = conn.cursor()
    rows = c.execute("select fid, fname, lname, contact from tblcontact where fname='maiji'")
    for row in c.fetchall():
        print(row)

This opens a context handle called conn which will automatically close the connection when you're done with your code (leaving no open connections which could be a problem) and secondly it's less code iterating directly over c.fetchall() and potentially be faster if the function supports iterations, which it probably will in later versions.

---

Here's one where you just add upp all the results into a hughe string (for dumping out to a file etc for instance). Note that this might fill your memory if the results are many, sequentially storing this to the file in such a case would be better, hence why you normally work with each database row individually for memory reasons.

with pymssql.connect(host='localhost', user='xx', password='xx', database='dbpython') as conn:
    c = conn.cursor()
    rows = c.execute("select fid, fname, lname, contact from tblcontact where fname='maiji'")
    string_result = ''
    for row in c.fetchall():
        string_result = row + '\n'

Answer 2

You should use an iterator instead of while loop.

conn = pymssql.connect(host='localhost', user='xx', password='xx', database='dbpython')
c = conn.cursor()
c.execute("select fid, fname, lname, contact from tblcontact where fname='maiji'")

for row in c:
    print(row)

c.close()