Different time format characters used by MySQL DATE_FORMAT() function are as follows −Time Format CharacterMeaning %HIt is used to abbreviate Hour on a 24-hour clock in two digits format like 00, 01, 02 up to 23. %hIt is used to abbreviate Hour on 12-hour clock in two digits format like 01, 02 up to 12. %iIt is used to abbreviate minutes in two digits format like 01, 02 up to 59. %lIt is used to abbreviate Hour on 12-hour clock in two digits format without zero-like 01, 02 up to 12. %pIt is used for A.M or P.M.%rIt is used to display time on 12-hour ... Read More

We can also use DATE_FORMAT() function to display the time in other formats. In this case, there would be two arguments of this function, first would be the time and second would be the format string.The following example will change the current time in specified format −mysql> SELECT DATE_FORMAT(NOW(), 'The time is %h:%i:%s %p'); +-----------------------------------------------+ | DATE_FORMAT(NOW(), 'The time is %h:%i:%s %p') | +-----------------------------------------------+ | The time is 06:02:28 AM                       | +-----------------------------------------------+ 1 row in set (0.00 sec)The following example will change the given time in specified format ... Read More

As we know that TRUNCATE will remove all the rows without removing table’s structure from the database. Same work can be done with the help of DELETE command on removing all the rows from the table. But there is a significant difference of re-initialization of PRIMARY KEY AUTO_INCREMENT between both the commands.Suppose a column is defined AUTO_INCREMENT having PRIMARY KEY CONSTRAINT, then on deleting all the rows with DELETE command would not re-initialize the table i.e. on entering the new rows, the AUTO_INCREMENT number will start after the last inserted row. In contrast, on using TRUNCATE, the table will be ... Read More

MySQL DELETE command is used to delete the row/s from a table. It is used with WHERE clause.SyntaxDELETE From Table_name WHERE Condition;ExampleIn the example below, we have deleted the rows from table ‘employee’ where id >=100.mysql> select * from employee; +------+--------+ | Id   | name   | +------+--------+ | 100  | Ram    | | 200  | Gaurav | | 300  | MOHAN  | +------+--------+ 3 rows in set (0.00 sec) mysql> delete from employee where id >=100; Query OK, 3 rows affected (0.06 sec) mysql> select * from employee; Empty set (0.00 sec)

The most significant difference between MySQL TRUNCATE and DROP command is that TRUNCATE command will not destroy table’s structure but in contrast DROP command will destroy table’s structure too.Examplemysql> Create table testing(id int PRIMARY KEY NOT NULL AUTO_INCREMENT, Name Varchar(20)); Query OK, 0 rows affected (0.24 sec) mysql> Insert into testing(Name) Values('Ram'), ('Mohan'), ('John'); Query OK, 3 rows affected (0.12 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> Select * from testing; +----+-------+ | id | Name  | +----+-------+ | 1  | Ram   | | 2  | Mohan | | 3  | John  | +----+-------+ 3 rows ... Read More

As the name explains, it is used to completely remove the table from the database.SyntaxDrop table table_name;Examplemysql> Drop table Student; Query OK, 0 rows affected (0.09 sec)The query above completely removes the ‘Student’ table from the database. We can observe as MySQL returns an error message after running the following query −mysql> Select * from Student; ERROR 1146 (42S02): Table 'query.student' doesn't exist

Eventually, we cannot remove all the columns from a table by using ALTER TABLE command with DROP keyword. In this case, MySQL will return an error message. It is demonstrated with the help of the following exampleSuppose in table ‘Employee’ we have two columns ‘name’ and ‘id’, now if we will use ALTER TABLE to remove both the columns then MySQL returns an error as followsmysql> ALTER TABLE employee drop column name, drop column id; ERROR 1090 (42000): You can't delete all columns with ALTER TABLE; use DROP TABLE instead

We can use keyword CHANGE to modify the column/s of an existing table. With CHANGE keyword we can change the name of the column and its definition both. Its syntax would be a bit different from the syntax of ALTER TABLE with MODIFY keyword.SyntaxAlter table table_name CHANGE old_columnname1 new_columnname1 datatype, CHANGE old_columnname2 new_columnname2 datatype… CHANGE old_columnnameN new_columnname datatype);ExampleIn the example below, with the help of CHANGE keyword in ALTER Command, the name and size of the columns ‘City’ and ‘RollNo’ have been modified.mysql> Alter table Student CHANGE Rollno Id int, CHANGE City Place Varchar(10); Query OK, 5 rows affected (0.40 ... Read More

Different date format characters used by MySQL DATE_FORMAT() function are as follows −Date Format CharacterMeaning %aIt is used to abbreviate the names of the weekdays like Sun, Mon, Tue, Wed, Thu, Fri and Sat.%bIt is used to abbreviate the names of the month like Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov and Dec.%cIt is used to abbreviate the number of the month like 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12. There will be no leading zero.%DIt is used to abbreviate the day of the month with an ordinal suffix like 1st, ... Read More

We need to use DATE_FORMAT() function to display the date in other formats. There would be two arguments of this function, first would be the date and second would be the format string.Example − Suppose in the table ‘date_testing we have three dates in the following formatmysql> Select * from date_testing; +------------+ | Date       | +------------+ | 2017-03-15 | | 2017-03-25 | | 2017-04-05 | +------------+ 3 rows in set (0.00 sec)Now DATE_FORMAT() function will change the format of the above dates in the format given by the user as follows −mysql> Select DATE_FORMAT(Date, '%W %D ... Read More