如何在python中为mysql连接执行异常处理

Question

I'm new to python , I want to know how to do exception handling in python in a proper way.I want to raise an exception for failure of db connection.I also don't want to include all the lines of code in try block.I want to raise connection failure exception.How to do this?

try:
    conn = MySQLdb.connect(host="mysql", user="root", passwd="password"
                           , db="database")
    mycursor = conn.cursor()
    query = "INSERT INTO table1(col1,col2,col3)VALUES(%s,%s,%s)"
    val = (x,y,z)
    mycursor.execute(query, val)
    conn.commit()
    conn.close()
    print("Data inserted to db")
except Exception as ex:
    print(ex)

Answer 1

    conn = MySQLdb.connect(host="mysql", user="root", passwd="password"
                           , db="database")
    mycursor = conn.cursor()
    query = "INSERT INTO table1(col1,col2,col3)VALUES(%s,%s,%s)"  
    try:
        mycursor.execute(query, val)
    except MySQLdb.Error, e:
        try:
            print "MySQL Error [%d]: %s" % (e.args[0], e.args[1])
            return None
        except IndexError:
            print "MySQL Error: %s" % str(e)
            return None
    except TypeError, e:
        print(e)
        return None
    except ValueError, e:
        print(e)
        return None
    finally:
        mycursor.close()
        conn.close()

Answer 2

Something like:

connected = False
try:
    conn = MySQLdb.connect(host="mysql", user="root", passwd="password"
                           , db="database")
    connected  = True
except MySQLError as ex:
    print(ex)
if connected:
    mycursor = conn.cursor()
    query = "INSERT INTO table1(col1,col2,col3)VALUES(%s,%s,%s)"
    val = (x,y,z)
    mycursor.execute(query, val)
    conn.commit()
    conn.close()
    print("Data inserted to db")