I have tried to query all elements from a list into an insertion query, I tried by making the list into a list of tuples and directly by adding the elements from the list. But it did not work, and I don't know the best practice for this as I am no SQL shark. I have below added the two different outputs I have before I do the query. I don't know which is easier to work with for this, but the code example is for the list of elements.
Output
['testuser', 'AskeMeyer']
and
[('testuser',), ('AskeMeyer',)]
Code to query
try:
conn = psycopg2.connect(host=ENDPOINT, port=PORT, database=DBNAME, user=USER, password=PASS, sslmode='require', sslrootcert="SSLCERTIFICATE")
cur = conn.cursor()
var_string = ', '.join(map(str, res))
sql = 'INSERT INTO users_from_group(name) VALUES %s;' % var_string)
cur.execute(sql)
error from above
Database connection failed due to syntax error at or near ")"
You need to use brackets and quotes in your insert statement, for example:
var_string = ', '.join([f"(\"{name}\")" for name in ['testuser', 'AskeMeyer']])
Also, there is a bracket at the end of your sql statement which causes the syntax error:
sql = 'INSERT INTO users_from_group(name) VALUES %s;' % var_string)
Should be
sql = 'INSERT INTO users_from_group(name) VALUES %s;' % var_string
it's not the proper way to store lists.
you should save it as json :
json.dumps(['testuser', 'AskeMeyer'] )
then save it
Try this:
var_string = '(' + ','.join(map(str, res)) + ')'
sql = 'INSERT INTO users_from_group(name) VALUES %s;' % var_string
I am trying to python to generate a script that generates unload command in redshift. I not an expert Python programmer. I need to where I can generate all columns for the unload list. If the column is of specific name, I need to replace with a function. The challenge I am facing is it appending "," to last item in the dictionary. Is there a way I can avoid the last comma? Any help would be appreciated.
import psycopg2 from psycopg2.extras
import RealDictCursor
try:
conn = psycopg2.connect("dbname='test' port='5439' user='scott' host='something.redshift.amazonaws.com' password='tiger'");
except:
print "Unable to connect to the database"
conn.cursor_factory = RealDictCursor
cur = conn.cursor()
conn.set_isolation_level( psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT )
try:
cur.execute("SELECT column from pg_table_def where schema_name='myschema' and table_name ='tab1' " );
except:
print "Unable to execute select statement from the database!"
result = cur.fetchall()
print "unload mychema.tab1 (select "
for row in result:
for key,value in row.items():
print "%s,"%(value)
print ") AWS Credentials here on..."
conn.close()
Use the join function on the list of values in each row:
print ",".join(row.values())
Briefly, the join function is called on a string which we can think of as the "glue", and takes a list of "pieces" as its argument. The result is a string of "pieces" "held together" by the "glue". Example:
>>> glue = "+"
>>> pieces = ["a", "b", "c"]
>>> glue.join(pieces)
"a+b+c"
(since row.values() returns a list, you don't actually need the comprehension, so it's even simpler than I wrote it at first)
Infact, this worked better.
columns = []
for row in result:
if (row['column_name'] == 'mycol1') or (row['column_name'] == 'mycol2') :
columns.append("func_sha1(" + row['column_name'] + "||" + salt +")")
else:
columns.append(row['column_name'])
print selstr + ",".join(columns)+" ) TO s3://"
Thanks for your help, Jon
I'm still trying to get the hang of python, so bear with me. please. I have this bit of code that I'm using from a book. The book does not properly show the white space in the code, so the spacing is my best guess. This code is supposed to break the results of a MySQL query into a more readable format.
if form is True:
columns_query = """DESCRIBE %s""" % (table)
print columns_query
columns_command = cursor.execute(columns_query)
headers = cursor.fetchall()
column_list = []
for record in headers:
column_list.append(record[0])
output=""
for record in results:
output = output + "===================================\n\n"
for field_no in xrange(0, len(column_list)):
output = output + column_list[field_no] + ": " + str(record[field_no]) + "\n"
output = output + "\n"
When I try to run it, I get the following:
Traceback (most recent call last):
File "odata_search.py", line 46, in <module>
output = output + column_list[field_no] + ": " + str(record[field_no]) + "\n"
IndexError: tuple index out of range
It has something to do with the str(record[field_no]) portion of the code, but that's what it looks like in the book, so I'm not sure what else to try.
Clearly len(record) != len(column_list). (specifically, column_list is longer than record). Is there a reason that you expect them to be the same length?
One "fix" would be something like:
for col,rec in zip(column_list,record):
output += col + ": " + str(rec) + "\n"
instead of:
for field_no in xrange(0, len(column_list)):
output = output + column_list[field_no] + ": " + str(record[field_no]) + "\n"
This will truncate the output at the shorter of column_list and record.
I would recommend using zip instead of range(0,len(...)) in any event. It's much more idiomatic.
The problem it turns out was both the white space and, more importantly, the MySQL query itself. I was pulling a list that were rows in a column instead of pulling all columns of a row, which is what the loops were written to concatenate. The number of records I would get back in the result of the wrong query was not equal to the number of results in the list that contained all the columns. The code was also intended to be a loop within a loop, so the spacing I have at the top is wrong. It should look like it does below. I added a couple of lines before it to show the query I had to modify:
Old statement looped like this:
statement = """select %s from %s where %s like '%s' limit 10""" % (column, table, column, term)
Should look like this:
statement = """select * from %s where %s like '%s' limit 10""" % (table, column, term)
command = cursor.execute(statement)
results = cursor.fetchall()
column_list = []
for record in results:
column_list.append(record[0])
Loop within a loop:
if form is True:
columns_query = """DESCRIBE %s""" % (table)
columns_command = cursor.execute(columns_query)
headers = cursor.fetchall()
column_list = []
for record in headers:
column_list.append(record[0])
output=""
for record in results:
output = output + "===================================\n\n"
for field_no in xrange(0, len(column_list)):
output = output + column_list[field_no] + ": " + str(record[field_no]) + "\n"
output = output + "\n"
I am trying to use a dict to do a SQL INSERT. The logic would basically be:
INSERT INTO table (dict.keys()) VALUES dict.values()
However, I am having a tough time figuring out the correct syntax / flow to do this. This is what I currently have:
# data = {...}
sorted_column_headers_list = []
sorted_column_values_list = []
for k, v in data.items():
sorted_column_headers_list.append(k)
sorted_column_values_list.append(v)
sorted_column_headers_string = ', '.join(sorted_column_headers_list)
sorted_column_values_string = ', '.join(sorted_column_values_list)
cursor.execute("""INSERT INTO title (%s)
VALUES (%s)""",
(sorted_column_headers_string, sorted_column_values_string))
From this I get a SQL exception (I think related to the fact that commas are also included in some of the values that I have). What would be the correct way to do the above?
I think the comment on using this with MySQL is not quite complete. MySQLdb doesn't do parameter substitution in the columns, just the values (IIUC) - so maybe more like
placeholders = ', '.join(['%s'] * len(myDict))
columns = ', '.join(myDict.keys())
sql = "INSERT INTO %s ( %s ) VALUES ( %s )" % (table, columns, placeholders)
# valid in Python 2
cursor.execute(sql, myDict.values())
# valid in Python 3
cursor.execute(sql, list(myDict.values()))
You're not getting escaping on the columns though, so you might want to check them first....
See http://mail.python.org/pipermail/tutor/2010-December/080701.html for a more complete solution
You want to add parameter placeholders to the query. This might get you what you need:
qmarks = ', '.join('?' * len(myDict))
qry = "Insert Into Table (%s) Values (%s)" % (qmarks, qmarks)
cursor.execute(qry, myDict.keys() + myDict.values())
Always good answers here, but in Python 3, you should write the following:
placeholder = ", ".join(["%s"] * len(dict))
stmt = "insert into `{table}` ({columns}) values ({values});".format(table=table_name, columns=",".join(dict.keys()), values=placeholder)
cur.execute(stmt, list(dict.values()))
Don't forget to convert dict.values() to a list because in Python 3, dict.values() returns a view, not a list.
Also, do NOT pour the dict.values() in stmt because it tears a quote out of a string by joining it, which caused MySQL error in inserting it. So you should always put it in cur.execute() dynamically.
I'm a little late to the party but there is another way that I tend to prefer since my data is usually in the form of a dict already. If you list the bind variables in the form of %(columnName)s you can use a dictionary to bind them at execute. This partially solves the problem of column ordering since the variables are bound in by name. I say partially because you still have to make sure that the columns & values portion of the insert are mapped correctly; but the dictionary itself can be in any order (since dicts are sort of unordered anyway)
There is probably a more pythonic way to achieve all this, but pulling the column names into a list and working off it ensures we have a static ordering to build the columns & values clauses.
data_dict = {'col1': 'value 1', 'col2': 'value 2', 'col3': 'value 3'}
columns = data_dict.keys()
cols_comma_separated = ', '.join(columns)
binds_comma_separated = ', '.join(['%(' + item + ')s' for item in columns])
sql = f'INSERT INTO yourtable ({cols_comma_separated}) VALUES ({binds_comma_separated})'
cur.execute(sql, data_dict)
Now whether or not it is a good idea to dynamically build your columns & values clause like this is a topic for a SQL injection thread.
table='mytable'
columns_string= '('+','.join(myDict.keys())+')'
values_string = '('+','.join(map(str,myDict.values()))+')'
sql = """INSERT INTO %s %s
VALUES %s"""%(table, columns_string,values_string)
I tried #furicle's solution but it still inputs everything as a string - if your dict is a mixed one then this may not work as you would want it to. I had a similar issue and this is what I came up with - this is only a query builder and you could use it (with changes) to work with any database of your choice. Have a look!
def ins_query_maker(tablename, rowdict):
keys = tuple(rowdict)
dictsize = len(rowdict)
sql = ''
for i in range(dictsize) :
if(type(rowdict[keys[i]]).__name__ == 'str'):
sql += '\'' + str(rowdict[keys[i]]) + '\''
else:
sql += str(rowdict[keys[i]])
if(i< dictsize-1):
sql += ', '
query = "insert into " + str(tablename) + " " + str(keys) + " values (" + sql + ")"
print(query) # for demo purposes we do this
return(query) #in real code we do this
This is crude and still needs sanity checks, etc, but it works as intended.
for a dict:
tab = {'idnumber': 1, 'fname': 'some', 'lname': 'dude', 'dob': '15/08/1947', 'mobile': 5550000914, 'age' : 70.4}
running the query I get the following output
results of query generated by the suite
This code worked for me (Python 3):
fields = (str(list(dictionary.keys()))[1:-1])
values = (str(list(dictionary.values()))[1:-1])
sql = 'INSERT INTO Table (' + fields + ') VALUES (' + values + ')'
cursor.execute(sql)
It does rely on the dictionary outputting its keys and values in the same order. I'm unclear if this is always true :)
When constructing queries dynamically it's important to ensure that both identifiers and values are correctly quoted. Otherwise you risk
SQL injection if untrusted data is processed
Errors if the column names require quoting (for example embedded spaces)
Data corruption or errors if values are incorrectly quoted (for example 2021-07-11 unquoted may be evaluated as 2003)
Quoting values is best delegated to the DB-API connector. However connector packages don't always provide a way to quote identifiers, so you may need to do this manually. MySQL uses backticks (`) to quote identifiers.
This code quotes identifiers and values. It works for MySQLdb, mysql.connector and pymysql and works for Python 3.5+.
data = {'col1': val1, 'col2': val2, ...}
# Compose a string of quoted column names
cols = ','.join([f'`{k}`' for k in data.keys()])
# Compose a string of placeholders for values
vals = ','.join(['%s'] * len(data))
# Create the SQL statement
stmt = f'INSERT INTO `tbl` ({cols}) VALUES ({vals})'
# Execute the statement, delegating the quoting of values to the connector
cur.execute(stmt, tuple(data.values()))
This is based on other answers here, but it uses back ticks around column names for cases in which you are using reserved words as column names and it it ensures that column names only contain letters, numbers, and underscores to thwart SQL injection attacks.
I've also written a similar upsert that works the same way as the insert but which overwrites data that duplicates the primary key.
import mysql.connector
import re
cnx = mysql.connector.connect(...)
def checkColumnNames(data):
for name in data.keys():
assert re.match(r'^[a-zA-Z0-9_]+$',name), "Bad column name: " + name
def insert(table, data):
checkColumnNames(data)
assert table, "No table specified"
placeholders = ', '.join(['%s'] * len(data))
columns = '`,`'.join(data.keys())
sql = "INSERT INTO `%s` (`%s`) VALUES (%s);" % (table, columns, placeholders)
cnx.cursor().execute(sql, list(data.values()))
def upsert(table, data):
checkColumnNames(data)
assert table, "No table specified"
placeholders = ', '.join(['%s'] * len(data))
columns = '`,`'.join(data.keys())
updates = '`' + '`=%s,`'.join(data.keys()) + '`=%s'
sql = "INSERT INTO `%s` (`%s`) VALUES (%s) ON DUPLICATE KEY UPDATE %s" % (table, columns, placeholders, updates)
cnx.cursor().execute(sql, list(data.values()) + list(data.values()))
Example usage
insert("animals", {
"id": 1,
"name": "Bob",
"type": "Alligator"
})
cnx.commit()
I used this thread for my usage and tried to keep it much simpler
ins_qry = "INSERT INTO {tablename} ({columns}) VALUES {values};" .format(
tablename=my_tablename,
columns=', '.join(myDict.keys()),
values=tuple(myDict.values())
)
cursor.execute(ins_qry)
Make sure to commit the data inserted, either using db_connection.commit() and use cursor.lastrowid, if you need the primary key of the inserted row
This works for me
cursor.execute("INSERT INTO table (col) VALUES ( %(col_value) )",
{'col_value': 123})
if you have list in which there are number of dictionaries
for example: lst=[d1,d2,d3,d4]
then below one will worked for me:
for i in lst:
placeholders = ', '.join(['%s'] * len(i))
columns = ', '.join(i.keys())
sql = "INSERT INTO %s ( %s ) VALUES ( %s )" % (table, columns, placeholders)
cursor.execute(sql,list(i.values()))
conn.commit()
Note:Dont ever forget to commit otherwise you wont be able to see columns and values inserted in table
columns = ', '.join(str(x).replace('/', '_') for x in row_dict.keys())
values = ', '.join("'" + str(x).replace('/', '_') + "'" for x in row_dict.values())
sql = "INSERT INTO %s ( %s ) VALUES ( %s );" % ("tablename", columns, values)
applicable for python3
Let's say our data is:
data = {
"name" : "fani",
"surname": "dogru",
"number" : 271990
}
This is my shorter version:
tablo = "table_name"
cols = ','.join([f" {k}" for k in data.keys()])
vals = ','.join([f"'{k}'" for k in data.values()])
stmt = f'INSERT INTO {tablo} ({cols}) VALUES ({vals})'
What about:
keys = str(dict.keys())
keys.replace('[', '(')
keys.replace(']', ')')
keys.replace("'",'')
vals = str(dict.values())
vals.replace('[', '(')
vals.replace(']', ')')
cur.execute('INSERT INTO table %s VALUES %s' % (keys, vals))
For python 3:
keys = str(dict.keys())[9:].replace('[', '').replace(']', '')
vals = str(dict.values())[11:].replace('[', '').replace(']', '')
...