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Yes, we can use DESCRIBE or EXPLAIN statements instead of SHOW COLUMNS statement to get the list of the columns in an existing table. In the example below we have applied DESCRIBE and EXPLAIN statement on ‘Employee’ table and got the same result set as got after SHOW COLUMNS statement −mysql> DESCRIBE Employee\G *************************** 1. row *************************** Field: Id Type: int(11) Null: YES Key: Default: NULL Extra: *************************** 2. row *************************** Field: Name Type: varchar(20) Null: YES Key: Default: NULL Extra: 2 rows in set (0.05 sec) ... Read More
With the help of following MySQL query, we can get the last day of previous month −mysql> SELECT LAST_DAY(now() - INTERVAL 1 MONTH) AS 'LAST DAY OF PREVIOUS MONTH'; +----------------------------+ | LAST DAY OF PREVIOUS MONTH | +----------------------------+ | 2017-09-30 | +----------------------------+ 1 row in set (0.00 sec)
With the help of following MySQL query, we can get the last day of next month −mysql> SELECT LAST_DAY(now() + INTERVAL 1 MONTH) AS 'LAST DAY OF NEXT MONTH'; +------------------------+ | LAST DAY OF NEXT MONTH | +------------------------+ | 2017-11-30 | +------------------------+ 1 row in set (0.00 sec)
Suppose if we have stored a date value as ‘0000-00-00’ in MySQL table then on extracting year value from such kind of date, MySQL will return 0. It would not be in either Year(2) or Year(4) format. To understand it we are using the following data from ‘detail_bday’ table −mysql> Select * from detail_bday; +----+---------+------------+ | Sr | Name | Birth_Date | +----+---------+------------+ | 1 | Saurabh | 1990-05-12 | | 2 | Raman | 1993-06-11 | | 3 | Gaurav | 1984-01-17 | | 4 | Rahul | 1993-06-11 | | 5 | Sonia ... Read More
You can format any time as per your requirement, but simple method to get time in readable format is asctime() −Example Live Demo#!/usr/bin/python import time; localtime = time.asctime( time.localtime(time.time()) ) print "Local current time :", localtimeOutputThis would produce the following result −Local current time : Tue Jan 13 10:17:09 2009
To translate a time instant from a seconds since the epoch floating-point value into a time-tuple, pass the floating-point value to a function (e.g., localtime) that returns a time-tuple with all nine items valid.Example Live Demo#!/usr/bin/python import time; localtime = time.localtime(time.time()) print "Local current time :", localtimeOutputThis would produce the following result, which could be formatted in any other presentable form −Local current time : time.struct_time(tm_year=2013, tm_mon=7, tm_mday=17, tm_hour=21, tm_min=26, tm_sec=3, tm_wday=2, tm_yday=198, tm_isdst=0)
Many of Python's time functions handle time as a tuple of 9 numbers, as shown below −IndexFieldValues04-digit year20081Month1 to 122Day1 to 313Hour0 to 234Minute0 to 595Second0 to 61 (60 or 61 are leap-seconds)6Day of Week0 to 6 (0 is Monday)7Day of year1 to 366 (Julian day)8Daylight savings-1, 0, 1, -1 means library determines DSTThe above tuple is equivalent to struct_time structure. This structure has following attributes −IndexAttributesValues0tm_year20081tm_mon1 to 122tm_mday1 to 313tm_hour0 to 234tm_min0 to 595tm_sec0 to 61 (60 or 61 are leap-seconds)6tm_wday0 to 6 (0 is Monday)7tm_yday1 to 366 (Julian day)8tm_isdst-1, 0, 1, -1 means library determines DSTRead More
Python includes the following dictionary functions −Sr.NoFunction with Description1cmp(dict1, dict2)Compares elements of both dict.2len(dict)Gives the total length of the dictionary. This would be equal to the number of items in the dictionary.3str(dict)Produces a printable string representation of a dictionary4type(variable)Returns the type of the passed variable. If passed variable is dictionary, then it would return a dictionary type.Python includes following dictionary methods −Sr.NoMethods with Description1dict.clear()Removes all elements of dictionary dict2dict.copy()Returns a shallow copy of dictionary dict3dict.fromkeys()Create a new dictionary with keys from seq and values set to value.4dict.get(key, default=None)For key key, returns value or default if key not in dictionary5dict.has_key(key)Returns true ... Read More
Dictionary values have no restrictions. They can be any arbitrary Python object, either standard objects or user-defined objects. However, same is not true for the keys.There are two important points to remember about dictionary keys −More than one entry per key not allowed. Which means no duplicate key is allowed. When duplicate keys encountered during assignment, the last assignment wins.ExampleFollowing is a simple example − Live Demo#!/usr/bin/python dict = {'Name': 'Zara', 'Age': 7, 'Name': 'Manni'} print "dict['Name']: ", dict['Name']OutputWhen the above code is executed, it produces the following result −dict['Name']: Manni Keys must be immutable. Which means you can use strings, ... Read More
You can either remove individual dictionary elements or clear the entire contents of a dictionary. You can also delete entire dictionary in a single operation.To explicitly remove an entire dictionary, just use the del statement.ExampleFollowing is a simple example − Live Demo#!/usr/bin/python dict = {'Name': 'Zara', 'Age': 7, 'Class': 'First'} del dict['Name']; # remove entry with key 'Name' dict.clear(); # remove all entries in dict del dict ; # delete entire dictionary print "dict['Age']: ", dict['Age'] print "dict['School']: ", dict['School']OutputThis produces the following result. Note that an exception is raised because after del dict dictionary does not exist any more −dict['Age']: Traceback (most ... Read More