The DROP TABLE removes the table completely and also removes all data. If you want to remove all data completely and wants the table structure, then you can use TRUNCATE TABLE command. The TRUNCATE command will recreate the table.Let us first check the DROP TABLE. For that, we will first create a table −mysql> create table DemoTable    (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    Name varchar(20)    ); Query OK, 0 rows affected (0.20 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Name) values('Larry'); Query OK, 1 row affected (0.07 sec) ... Read More

You can use elt() along with rand() for this. Let us select random number from a specific list.mysql> SELECT ELT(FLOOR(RAND() * 10) + 1,    100, 200, 300, 400, 500, 600, 700, 800, 900, 1000) AS random_value_from_listOfValues;This will produce the following output −+--------------------------------+ | random_value_from_listOfValues | +--------------------------------+ | 1000 | +--------------------------------+ 1 row in set (0.00 sec)Now we will run the query again to select random number from a specific list.mysql> SELECT ELT(FLOOR(RAND() * ... Read More

You can use DEFAULT CURRENT_TIMESTAMP. Keep in mind that it will work only at the time of insertion. Let us first create a table −mysql> create table DemoTable    (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    Arrivaltime TIMESTAMP DEFAULT CURRENT_TIMESTAMP    ); Query OK, 0 rows affected (0.31 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Arrivaltime) values('2018-01-31 10:34:56'); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable values(); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(Arrivaltime) values('2019-01-31 11:10:12'); Query OK, 1 row affected (0.04 sec)Display ... Read More

You need to give name explicitly or you can remove AS command. Let us first create a table −mysql> create table DemoTable    (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    Name varchar(20)    ); Query OK, 0 rows affected (0.21 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Name) values('John'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable(Name) values('Larry'); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable(Name) values('Sam'); Query OK, 1 row affected (0.06 sec)Display all records from the table using select statement −mysql> select ... Read More

To fetch only N rows at a time, you can use LIMIT operator. Following is the syntax −select *from yourTableNameLIMIT 0, N;Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Name varchar(20) ); Query OK, 0 rows affected (0.25 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Name) values('John'); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable(Name) values('Larry'); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable(Name) values('Bob'); ... Read More

Use aggregate function SUM() to get the sum of a column in al rows. Let us first create a table −mysql> create table DemoTable    (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Amount int    ); Query OK, 0 rows affected (0.20 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Amount) values(50); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable(Amount) values(60); Query OK, 1 row affected (0.04 sec) mysql> insert into DemoTable(Amount) values(70); Query OK, 1 row affected (0.10 sec)Display all records from the table using select statement −mysql> ... Read More

To insert when a record does not exist, set the column as UNIQUE INDEX. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName varchar(20) ); Query OK, 0 rows affected (0.30 sec)Following is the query to create unique index to insert record which does not exist in the ‘FirstName’ column −mysql> CREATE UNIQUE INDEX index_on_FirstName ON DemoTable(FirstName); Query OK, 0 rows affected (0.56 sec) Records: 0 Duplicates: 0 Warnings: 0Insert some records in the table using insert command. ... Read More

You need to follow some steps to add a new column after a specific column and defining default value. In order to achieve this, you need to use ALTER command. Let us first create a table −mysql> create table DemoTable    (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentFirstName varchar(20),    StudentAge int,    StudentCountryName varchar(100)    ); Query OK, 0 rows affected (0.21 sec)Let us check the description of table −mysql> desc DemoTable;This will produce the following output −+--------------------+--------------+------+-----+---------+----------------+ | Field              | Type         | Null | ... Read More

For using MySQL CASE statement while using UPDATE Query, you can use CASE statement. Let us first create a table −mysql> create table DemoTable    (    UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY, UserScore int    ); Query OK, 0 rows affected (0.29 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(UserScore) values(100); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable(UserScore) values(110); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable(UserScore) values(120); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable(UserScore) values(200); Query OK, 1 ... Read More

You need to use FIND_IN_SET() for this. Let us first create a table −mysql> create table DemoTable ( CustomerId int NOT NULL AUTO_INCREMENT PRIMARY KEY, CustomerName varchar(20), CustomerAllProductPrice text ); Query OK, 0 rows affected (0.30 sec)Insert some records in the table using insert command. Here, we are inserting numbers separated by comma −mysql> insert into DemoTable(CustomerName, CustomerAllProductPrice) values('Chris', '245, 345, 678, 90, 45, 56, 78'); Query OK, 1 row affected (0.03 sec) mysql> insert into DemoTable(CustomerName, CustomerAllProductPrice) values('Chris', '98, 99, 90, 56, 77'); ... Read More