Creating a dynamic SQL Query from Python
Question:
I am using the below set of parameters to create a dynamic sql query and running it from python.
target_column = 'connect_status'
table_name = 'public.main_table'
query_params = {'month_date' : '201801',
'churn_date' : ['201802','201803','201804'],
'disco_target' : '1-3 Month Disco'
}
for churn in query_params['churn_date']:
sql_data_sample = str("""select * from {1}
where dt = %(month_date)s
and churn_date = %(churn)s
and {0} IN (%(disco_target)s,'No Disco') order by random() limit 5000
;""").format(target_column,table_name)
print (sql_data_sample)
df_data_sample = pd.read_sql(sql_data_sample,con = cnxn,params = query_params)
However this gives an DatabaseError:
Execution failed on sql 'select * from public.main_table
where dt = %(month_date)s
and churn_date = %(churn)s
and connect_status IN (%(disco_target)s,'No Disco') order by random() limit 5000
;': 'churn'
Can someone please help me to correct this?
Answers:
The problem is because churn
is not available in query_params
. Modify your code to
for churn in query_params['churn_date']:
try:
sql_data_sample = str("""select * from {1}
where dt = %(month_date)s
and churn_date = %(churn)s
and {0} IN (%(disco_target)s,'No Disco') order by random() limit 5000
;""").format(target_column,table_name)
print (sql_data_sample)
query_params['churn'] = churn
df_data_sample = pd.read_sql(sql_data_sample,con = cnxn,params = query_params)
except (Exception, psycopg2.DatabaseError) as error:
print(error)
Your string format expression references data in your query_params but query_params isn’t referenced in the format function’s parameters. Have a look at your month_date
and disco_target
usage.
#Use this python to write the dynamic update query for postgreSql
def updateQuery(self,tableName,setFields,setValues,whereFields,whereValues):
querySetfields = None
queryWhereFields = None
# Loop for set fields
for i in range(len(setFields)):
if querySetfields is None:
querySetfields=setFields[i]+"='"+setValues[i]+"'"
else:
querySetfields=querySetfields+","+setFields[i]+"='"+setValues[i]+"'"
# Loop for whereFields
for i in range(len(whereFields)):
if queryWhereFields is None:
queryWhereFields=whereFields[i]+"='"+whereValues[i]+"'"
else:
queryWhereFields=queryWhereFields+","+whereFields[i]+"='"+whereValues[i]+"'"
#Form the complete update query
query="UPDATE "+tableName+" SET "+querySetfields+" WHERE "+queryWhereFields
return query
I am using the below set of parameters to create a dynamic sql query and running it from python.
target_column = 'connect_status'
table_name = 'public.main_table'
query_params = {'month_date' : '201801',
'churn_date' : ['201802','201803','201804'],
'disco_target' : '1-3 Month Disco'
}
for churn in query_params['churn_date']:
sql_data_sample = str("""select * from {1}
where dt = %(month_date)s
and churn_date = %(churn)s
and {0} IN (%(disco_target)s,'No Disco') order by random() limit 5000
;""").format(target_column,table_name)
print (sql_data_sample)
df_data_sample = pd.read_sql(sql_data_sample,con = cnxn,params = query_params)
However this gives an DatabaseError:
Execution failed on sql 'select * from public.main_table
where dt = %(month_date)s
and churn_date = %(churn)s
and connect_status IN (%(disco_target)s,'No Disco') order by random() limit 5000
;': 'churn'
Can someone please help me to correct this?
The problem is because churn
is not available in query_params
. Modify your code to
for churn in query_params['churn_date']:
try:
sql_data_sample = str("""select * from {1}
where dt = %(month_date)s
and churn_date = %(churn)s
and {0} IN (%(disco_target)s,'No Disco') order by random() limit 5000
;""").format(target_column,table_name)
print (sql_data_sample)
query_params['churn'] = churn
df_data_sample = pd.read_sql(sql_data_sample,con = cnxn,params = query_params)
except (Exception, psycopg2.DatabaseError) as error:
print(error)
Your string format expression references data in your query_params but query_params isn’t referenced in the format function’s parameters. Have a look at your month_date
and disco_target
usage.
#Use this python to write the dynamic update query for postgreSql
def updateQuery(self,tableName,setFields,setValues,whereFields,whereValues):
querySetfields = None
queryWhereFields = None
# Loop for set fields
for i in range(len(setFields)):
if querySetfields is None:
querySetfields=setFields[i]+"='"+setValues[i]+"'"
else:
querySetfields=querySetfields+","+setFields[i]+"='"+setValues[i]+"'"
# Loop for whereFields
for i in range(len(whereFields)):
if queryWhereFields is None:
queryWhereFields=whereFields[i]+"='"+whereValues[i]+"'"
else:
queryWhereFields=queryWhereFields+","+whereFields[i]+"='"+whereValues[i]+"'"
#Form the complete update query
query="UPDATE "+tableName+" SET "+querySetfields+" WHERE "+queryWhereFields
return query