Can someone please explain why the first loop gets exited, when the second loop is done.
First i get all table names in database(Total 4 results)
Then i want to get all data from that table.
But i only get the data from the first table for some reason.
If i remove the loop that gets the data from the table, then it runs the first for loop all the way to the end.
#Get all tables in database file
for tablename in c.execute("SELECT name FROM sqlite_master WHERE type='table';"):
print(tablename[0])
for elementdate in c.execute('SELECT * FROM %s ORDER BY Date DESC' % tablename[0]):
print(elementdate)
Output:
table_1
(1, '20120210', 360)
(2, '20100210', 204)
Loop Excited
Same code just without last for loop
#Get table names
for tablename in c.execute("SELECT name FROM sqlite_master WHERE type='table';"):
print(tablename[0])
#for elementdate in c.execute('SELECT * FROM %s ORDER BY Date DESC' % tablename[0]):
# print(elementdate)
Output:
table_1
table_2
table_3
table_4
Loop Excited
Have i found an error or am i just dumb?
You shouldn't execute few queries in the same cursor before fetching results of first one:
c.execute("SELECT name FROM sqlite_master WHERE type='table'")
tables = c.fetchall()
for tablename in tables:
print(tablename[0])
c.execute('SELECT * FROM %s ORDER BY Date DESC' % tablename[0])
for elementdate in c.fetchall():
print(elementdate)
A single cursor object works only with a single query at a time; execute() overwrites any previous results.
If you want to execute two queries at the same time, use two cursors:
c = db.cursor()
c2 = db.cursor()
for row in c.execute("SELECT name FROM sqlite_master WHERE type='table'"):
tablename = row[0]
for row2 in c2.execute("SELECT * FROM %s ORDER BY Date DESC" % tablename):
...
Note: it would be a bad idea to modify the table while some other query on it is still running.
Related
firstly apologies for the basic question, just starting off with Python.
I have the following code:
import sqlite3
conn = sqlite3.connect("test.sqb")
cursor = conn.cursor()
sql = "SELECT * FROM report WHERE type LIKE 'C%'"
cursor.execute(sql)
data = cursor.fetchall()
for row in data:
print (row[0])
cursor.execute("UPDATE report SET route='ABCDE'")
conn.commit()
conn.close()
Why is it updating all records and not just the filtered records from sql query, even though the print (row[0]) just shows the filtered records.
Many thanks.
What's actually happening is you are running this query for each record returned from the SELECT query.
UPDATE report SET route='ABCDE'
If you only want to update route where type starts with C add the criteria to the UPDATE query and execute it once.
import sqlite3
conn = sqlite3.connect("test.sqb")
cursor = conn.cursor()
sql = "SELECT * FROM report WHERE type LIKE 'C%'"
cursor.execute(sql)
data = cursor.fetchall()
cursor.execute("UPDATE report SET route='ABCDE' WHERE type LIKE 'C%'")
conn.commit()
conn.close()
I have an issue when displaying a value in python retrieved from oracle table into CLOB field:
Oracle query:
SELECT EXTRACTVALUE(xmltype(t.xml), '/DCResponse/ResponseInfo/ApplicationId')
FROM table t
WHERE id = 2
Value displayed in Oracle Client
5701200
Python code
import cx_Oracle
conn = cx_Oracle.Connection("user/pwd#localhost:1521/orcl")
cursor = conn.cursor()
cursor.execute("""SELECT EXTRACTVALUE(xmltype(t.xml),'/DCResponse/ResponseInfo/ApplicationId') FROM table t where id = 2""")
for row in cursor:
print(row)
Python Console: Nothing is displayed!!! I want to show:5701200
Please Help.
Best Regards
Giancarlo
There are only a few issues with your code :
Replace cx_Oracle.Connection with cx_Oracle.connect
Be careful about the indentation related to the print(row)
Triple double-quotes, within the SELECT statement, are redundant,
replace them with Single double-quotes
Prefer Using print(row[0]) in order to return the desired number rather than
a tuple printed.
import cx_Oracle
conn = cx_Oracle.connect('user/pwd#localhost:1521/orcl')
cursor = conn.cursor()
query = "SELECT EXTRACTVALUE(xmltype(t.xml),'/DCResponse/ResponseInfo/ApplicationId')"
query += " FROM tab t "
query += " WHERE t.ID = 2 "
cursor.execute( query )
for row in cursor:
print(row[0])
Assigning a query to a variable not required, as stated in my case, but preferable to use in order to display the long SELECT statement decently.
If you want to iterate over result, use this one:
for row in cursor.execute("sql_query")
print(row)
or you can fetch each row like this:
cursor = conn.cursor()
cursor.execute("sql_query")
while True:
row = cursor.fetchone()
print(row)
I have big XML files to parse (about 200k lines and 10MB). The structure is following:
<el1>
<el2>
<el3>
<el3-1>...</el3-1>
<el3-2>...</el3-2>
</el3>
<el4>
<el4-1>...</el4-1>
<el4-2>...</el4-2>
</el4>
<el5>
<el5-1>...</el4-1>
<el5-2>...</el5-2>
</el5>
</el2>
</el1>
Here is my code:
tree = ElementTree.parse(filename)
doc = tree.getroot()
cursor.execute(
'INSERT INTO first_table() VALUES()',
())
cursor.execute('SELECT id FROM first_table ORDER BY id DESC limit 1')
row = cursor.fetchone()
v_id1 = row[0]
for el1 in doc.findall('EL1'):
cursor.execute(
'INSERT INTO second_table() VALUES(v_id1)',
(v_id1))
cursor.execute(
'SELECT id FROM second_table ORDER BY id DESC limit 1')
row = cursor.fetchone()
v_id2 = row[0]
for el2 in el1.findall('EL2'):
cursor.execute(
'INSERT INTO third_table(v_id2) VALUES()',
(v_id2))
cursor.execute(
'SELECT id FROM third_table ORDER BY id DESC limit 1')
row = cursor.fetchone()
v_id3 = row[0]
for el3 in el2.findall('EL3'):
cursor.execute(
'INSERT INTO fourth_table(v_id3) VALUES()',
(v_id3))
cursor.execute(
'SELECT id FROM fourth_table ORDER BY id DESC limit 1')
row = cursor.fetchone()
v_id4 = row[0]
for el4 in el3.findall('EL4'):
cursor.execute(
'INSERT INTO fifth_table(v_id4) VALUES()',
(v_id4))
for el5 in el4.findall('EL5'):
cursor.execute(
'INSERT INTO sixth_table(v_id4) VALUES()',
(v_id4))
cursor.execute(
'SELECT id FROM sixth_table ORDER BY id DESC limit 1')
row = cursor.fetchone()
v_id5 = row[0]
...
conn.commit()
Basically I get values from attributes and send them into the database. When I need to process nested elements, I have to SELECT last inserted ID from the database and INSERT it as a foreign key into the next INSERT statement.
The whole process takes about 50s but apparently it's too long for the data I have. The SELECT statements for sure take some time, but I already selecting only 1 attribute on last row.
I don't know if it can be faster since I'm not good at programming so I ask you guys.
You have 4 nested for loops. That's why. It is O(n^4).
name=input("input CUSTOMERID to search :")
# Prepare SQL query to view all records of a specific person from
# the SALESPRODUCTS TABLE LINKED WITH SALESPERSON TABLE.
sql = "SELECT * selling_products.customer \
FROM customer \
WHERE customer_products.CUSTOMERID == name"
# Execute the SQL command
cursor.execute(sql)
# Fetch all the rows the sql result of SQL1.
results = cursor.fetchall()
print("\n\n****** TABLE MASTERLIST*********")
print("CUSTOMERID \t PRODUCTID \t DATEOFPURCHASE")
print("**************")
for row in results:
print (row[0],row[1],row[2])
Python would compile the code above, but it will not return any output. Help would be very much appreciated :)
i think you sql should be:
sql = """SELECT * selling_products.customer
FROM customer
WHERE customer_products.CUSTOMERID == {name}""".format(name=name)
I have a MySQL Table named TBLTEST with two columns ID and qSQL. Each qSQL has SQL queries in it.
I have another table FACTRESTTBL.
There are 10 rows in the table TBLTEST.
For example, On TBLTEST lets take id =4 and qSQL ="select id, city, state from ABC".
How can I insert into the FACTRESTTBL from TBLTEST using python, may be using dictionary?
Thx!
You can use MySQLdb for Python.
Sample code (you'll need to debug it as I have no way of running it here):
#!/usr/bin/python
import MySQLdb
# Open database connection
db = MySQLdb.connect("localhost","testuser","test123","TESTDB" )
# prepare a cursor object using cursor() method
cursor = db.cursor()
# Select qSQL with id=4.
cursor.execute("SELECT qSQL FROM TBLTEST WHERE id = 4")
# Fetch a single row using fetchone() method.
results = cursor.fetchone()
qSQL = results[0]
cursor.execute(qSQL)
# Fetch all the rows in a list of lists.
qSQLresults = cursor.fetchall()
for row in qSQLresults:
id = row[0]
city = row[1]
#SQL query to INSERT a record into the table FACTRESTTBL.
cursor.execute('''INSERT into FACTRESTTBL (id, city)
values (%s, %s)''',
(id, city))
# Commit your changes in the database
db.commit()
# disconnect from server
db.close()