How to use variables in PostgreSQL in Python

Question

My Sounds table has 7 columns: Start_Time , End_Time , Salience_Label , Class_label , Bitrate , Bitdepth , Samplerate .

I want to insert some values into this table with the command

cursor.execute("INSERT INTO Sounds VALUES (%s, %s, %s, %s, %s, %s, %s)",(start_time, end_time, salience_label, class_label, samplerate, bitrate, bitdepth))



try:
   conn = psycopg2.connect(conn_string)
   cursor = conn.cursor()

.... doing staff for getting values for my variables ...

   cursor.execute("INSERT INTO Sounds VALUES (%s, %s, %s, %s, %s, %s, %s)",(start_time, end_time, salience_label, class_label, samplerate, bitrate, bitdepth))
   print "Connected!\n"
except:
 print "I am unable to connect to the database"

cursor.close()
conn.close()
print('Close conection')

Answer 1

While testing do not catch exceptions. Make the parameters a single tuple as Psycopg will adapt it to a record. Use mogrify to check what is being sent to the server:

conn = psycopg2.connect(conn_string)
cursor = conn.cursor()

insert = "insert into Sounds values %s"
parameters = (
    start_time, end_time, salience_label, 
    class_label, samplerate, bitrate, bitdepth
)

print cursor.mogrify(insert, (parameters,))
cursor.execute(insert, (parameters,))

conn.commit()
cursor.close()
conn.close()

BTW, the good practice is to name the columns which will receive the data like in:

insert into t (col_a, col_b) values (1, 'a')

That will avoid some problems.