I'm creating a program where I need to check if a certain cell in a table equals a string value and, if it does not, to not change that value. Here is some snippet of the code for clarification:
if (db.execute("SELECT :rowchosen FROM userboard WHERE column=:columnchosen", rowchosen = rowchosen, columnchosen = columnchosen)) == '-'):
#change value of cell
else:
#go to a new page that displays an error
Yet, whenever I run this code, I always get an error because the value (I believe) prints as a dictionary value, something like {"row" = 'row'} of that sort. Any help/advice as to why this happens?
Are you sure that userboard is the database and not the table?
i think, here is what you want to do
conn = sqlite3.connect(db_file)
cur = conn.cursor()
cur.execute("SELECT * FROM userboard WHERE one=?", (columnchosen,))
rows = cur.fetchall()
for row in rows:
print(row)
now, in the loop for row in rows: you need to perform your check. For all the rows returned, you need to check each row for - in the appropriate column
also check out http://www.sqlitetutorial.net/sqlite-python/sqlite-python-select/
Related
I'm working on a project where I need to get data from my SQL Server, but there is a catch. In total there is around 100.000 rows in the specific column I need the data out of but I only need the last 20.000 - 30.000 rows of it.
I use the casual connection string and stored procedure but is there a way to select a specific row to start from? (for example let it start at row 70.000)
try:
CONNECTION_STRING = 'DRIVER='+driver+';SERVER='+server+';DATABASE='+databaseName+';UID='+username+';PWD='+ password
conn = pyodbc.connect(CONNECTION_STRING)
cursor = conn.cursor()
storedproc = "*"
cursor.execute(storedproc)
row = cursor.fetchone()
while row:
OID = ((int(row[1])))
print(OID)
So my question: is there a way (for example) set cursor.fetchone to row 70.000 instead of 1? Or is there another way to do that?
Thanks in advance!
I Have this example of sql database. I want to use a certain item from the database in math calculation but I can't because the value looks like this: (25.0,) instead of just 25.0. Please see the attached picture
https://imgur.com/a/j7JOZ5H
import sqlite3
#Create the database:
connection = sqlite3.connect('DataBase.db')
c = connection.cursor()
c.execute('CREATE TABLE IF NOT EXISTS table1 (name TEXT,age NUMBER)')
c.execute("INSERT INTO table1 VALUES('Jhon',25)")
#Pull out the value:
c.execute('SELECT age FROM table1')
data =c.fetchall()
print(data[0])
#simple math calculation:
r=data[0]+1
print(r)
According to Python's PEP 249, the specification for most DB-APIs including sqlite3, fetchall returns a sequence of sequences, usually list of tuples. Therefore, to retrieve the single value in first column to do arithmetic, index the return twice: for specific row and then specific position in row.
data = c.fetchall()
data[0][0]
Alternatively, fetchone returns a single row, either first or next row, in resultset, so simply index once: the position in single row.
data = c.fetchone()
data[0]
The returned data from fetchall always comes back as a list of tuples, even if the tuple only contains 1 value. Your data variable should be:
[(25,)]
You need to use:
print(data[0][0])
r = data[0][0] + 1
print(r)
For example, if I iterate over a query using:
for row in cursor:
And I want to make a comparison like:
if row[0] == previousrow[0]:
#do something
How can I actually access the previous row?
If you wanted to access the previous row from your for loop, you could use the following code.
previousrow = None
for row in cursor:
if (!(previousrow is None)):
# do your comparison with previous row and row here
previousrow = row
I don't write Python, but I think this compiles and should work for you.
I select 1 column from a table in a database. I want to iterate through each of the results. Why is it when I do this it’s a tuple instead of a single value?
con = psycopg2.connect(…)
cur = con.cursor()
stmt = "SELECT DISTINCT inventory_pkg FROM {}.{} WHERE inventory_pkg IS NOT NULL;".format(schema, tableName)
cur.execute(stmt)
con.commit()
referenced = cur.fetchall()
for destTbl in referenced:#why is destTbl a single element tuple?
print('destTbl: '+str(referenced))
stmt = "SELECT attr_name, attr_rule FROM {}.{} WHERE ppm_table_name = {};".format(schema, tableName, destTbl)#this fails because the where clause gets messed up because ‘destTbl’ has a comma after it
cur.execute(stmt)
Because that's what the db api does: always returns a tuple for each row in the result.
It's pretty simple to refer to destTbl[0] wherever you need to.
Because you are getting rows from your database, and the API is being consistent.
If your query asked for * columns, or a specific number of columns that is greater than 1, you'd also need a tuple or list to hold those columns for each row.
In other words, just because you only have one column in this query doesn't mean the API suddenly will change what kind of object it returns to model a row.
Simply always treat a row as a sequence and use indexing or tuple assignment to get a specific value out. Use:
inventory_pkg = destTbl[0]
or
inventory_pkg, = destTbl
for example.
To sum it up. I have data in a row of a db (MySQL). This data are used in the script to calculate a value. A for loop is used to calculate this value for each row in the table.
The Problem: The results stored in the variable meant have to be updated in a different column of the same row.
I tried to include the update command in the for loop but I get an error (see below). If I do not include the update-command in the for loop I just get the result of the last row but for all rows!
The script:
for row in rows:
for col in row:
x = map(str.strip,col.lower().split())
st = map(lambda wo: abo.get(wo, 0), x)
meant = numpy.meant(st)
cur.execute("""UPDATE table_x SET result = %s Where text = %s""",(meant, rows))
Unfortunately I am getting this error:
Programming Error: (1064, 'You have an error in your SQL syntax; check the manual...
How can I update the column with each calculated value (meant) of that row?
As I see rows is a list ( or an iterable )
and in your query, you are binding the placeholder with rows ( instead of row? )
cur.execute("""UPDATE table_x SET result = %s Where text = %s""",(meant, rows)
That would most probably create a syntax error.