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Let us first create a table −mysql> create table DemoTable ( isValidUser boolean ); Query OK, 0 rows affected (0.70 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(true); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values(false); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable values(false); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values(true); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(true); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(true); Query OK, 1 row affected ... Read More
Let us first create a table −mysql> create table DemoTable ( FirstDate datetime, SecondDate datetime ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2019-01-21', '2018-01-21'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('2019-10-04', '2019-08-14'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('2019-05-01', '2019-09-11'); Query OK, 1 row affected (0.65 sec) mysql> insert into DemoTable values(NULL, NULL); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('2019-03-01', NULL); Query OK, 1 row affected (0.13 sec)Display all records ... Read More
First, you need to prepare a query and then you need to execute the PREPARED statement to dynamically choose a column in MySQL.Let us first create a table −mysql> create table DemoTable ( EmployeeName varchar(100) ); Query OK, 0 rows affected (0.77 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John Doe'); Query OK, 1 row affected (0.18 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+--------------+ | EmployeeName | +--------------+ | John Doe | +--------------+ 1 row in set ... Read More
Let us first create a table −mysql> create table DemoTable ( AdmissionDate varchar(100) ); Query OK, 0 rows affected (1.06 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2018-01-21'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('2019-08-13'); Query OK, 1 row affected (0.56 sec) mysql> insert into DemoTable values('2019-07-08'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('2016-02-12'); Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+---------------+ | AdmissionDate | +---------------+ ... Read More
Here we will see one interesting problem to sort an array based on the set-bits. When an element in the array has higher number of set-bits, then that will be placed before another element which has lower number of set bits. Suppose some numbers are 12, 15, 7. So the set bits are basically number of 1’s in their binary representation. These are 1100 (12), 1111 (15), and 0111 (7). So after sorting it will be look like this −1111, 0111, 1100 (15, 7, 12)Here we have to find the number of set-bits at first. Then we will use the ... Read More
Let us first create a table −mysql> create table DemoTable ( FirstName varchar(100), LastName varchar(100) ); Query OK, 0 rows affected (0.92 sec) mysql> alter table DemoTable add index(FirstName, LastName); Query OK, 0 rows affected (1.00 sec) Records: 0 Duplicates: 0 Warnings: 0Insert some records in the table using insert command −mysql> insert into DemoTable values('Adam', 'Smith'); Query OK, 1 row affected (0.73 sec) mysql> insert into DemoTable values('Adam', 'Smith'); Query OK, 1 row affected (1.17 sec) mysql> insert into DemoTable values('John', 'Doe'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('Carol', 'Taylor'); Query OK, ... Read More
For this, use UNION. Let us first create a table −mysql> create table DemoTable ( Name1 varchar(100), Name2 varchar(100) ); Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert commandmysql> insert into DemoTable values('Adam', 'Bob'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('Adam', 'Bob'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('David', 'Chris'); Query OK, 1 row affected (0.13 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+-------+-------+ | Name1 | Name2 | +-------+-------+ | ... Read More
For this, use a CASE statement. Let us first create a table −mysql> create table DemoTable ( Value char(1) ); Query OK, 0 rows affected (1.21 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('a'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('b'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('a'); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable values('a'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('b'); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable ... Read More
Yes, we can use INTERVAL while inserting data records. Let us first create a table −mysql> create table DemoTable ( ArrivalTime datetime ); Query OK, 0 rows affected (0.52 sec)Insert some records in the table using insert command. Here, we are using INTERVAL keyword for incrementing the date records while inserting −mysql> insert into DemoTable values(date_add(now(), interval 4 hour)); Query OK, 1 row affected (0.41 sec) mysql> insert into DemoTable values(date_add('2016-01-31 10:40:50', interval 2 hour)); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values(date_add('2015-05-01 12:00:00', interval 1 hour)); Query OK, 1 row affected (0.25 sec) mysql> ... Read More
Yes, you can give the year as a column name in MySQL table since it isn’t a reserved word. Let us first create a table −mysql> create table DemoTable ( Year int ); Query OK, 0 rows affected (0.87 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(1995); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(2019); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values(2016); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values(2018); Query OK, 1 row affected (0.13 sec)Display all records from ... Read More