Let us first create a table −mysql> create table DemoTable (    Logouttime time ); Query OK, 0 rows affected (0.62 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('5:50:00'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('6:10:10'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('8:00:50'); 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 −+------------+ | Logouttime | +------------+ | 05:50:00 | | 06:10:10 | | 08:00:50 ... Read More

For this, you can use the aggregate function SUM(). Let us first create a table −mysql> create table DemoTable (    isMarried tinyint(1) ); Query OK, 0 rows affected (0.84 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(0); Query OK, 1 row affected (0.26 sec) mysql> insert into DemoTable values(1); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(1); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values(0); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values(1); Query OK, 1 row affected (0.19 sec) mysql> ... Read More

Let’s say you have set dates in the VARCHAR format. Now if you want to update the format, then use the UPDATE command along with STR_TO_DATE(). The syntax is as follows −update yourTableName set yourColumnName=str_to_date(yourColumnName, '%m/%d/%Y');Let us first create a table −mysql> create table DemoTable (    DueDate varchar(100) ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('12/01/2019'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('01/31/2016'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('03/17/2018'); Query OK, 1 row affected (0.17 ... Read More

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

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