Let us first create a table −mysql> create table DemoTable1471    -> (    -> EmployeeJoiningDate date,    -> EmployeeRelievingDate date    -> ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1471 values('2018-06-21', '2018-12-21'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1471 values('2017-01-19', '2019-01-31'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1471 values('2015-12-31', '2016-03-01'); Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −mysql> select * from DemoTable1471;This will produce the following output −+---------------------+-----------------------+ | EmployeeJoiningDate | ... Read More

For this, use COALESCE(). Let us first create a table −mysql> create table DemoTable1470    -> (    -> FirstName varchar(20),    -> Age int    -> ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1470 values('Robert', 23); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable1470 values('Bob', NULL); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1470 values(NULL, 25); Query OK, 1 row affected (0.15 sec)Display all records from the table using select statement −mysql> select * from DemoTable1470;This will produce the following output ... Read More

To remove index from a MySQL table, the syntax is as follows −alter table yourTableName drop index `yourIndexName`;Let us first create a table −Mysql> create table DemoTable1469    -> (    -> StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> StudentName varchar(40),    -> StudentAge int    -> ); Query OK, 0 rows affected (0.78 sec)Following is the query to add index on column name −mysql> create index `Student Name_Index` on DemoTable1469(StudentName); Query OK, 0 rows affected (0.33 sec) Records: 0  Duplicates: 0  Warnings: 0Let us check the table description −mysql> desc DemoTable1469;This will produce the following output −+-------------+-------------+------+-----+---------+----------------+ ... Read More

Let us first create a table −mysql> create table DemoTable1468    -> (    -> Id int,    -> Name varchar(20),    -> Age int    -> ); Query OK, 0 rows affected (1.21 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1468 values(100, 'Chris', 23); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable1468 values(101, 'Bob', 25); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1468 values(102, 'David', 30); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable1468 values(100, 'Chris', 23); Query OK, 1 row affected (0.35 sec) mysql> ... Read More

For this, you can use GROUP BY HAVING clause. Let us first create a table −mysql> create table DemoTable1467    -> (    -> Id int,    -> Name varchar(20)    -> ); Query OK, 0 rows affected (0.64 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1467 values(100, 'Chris'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable1467 values(110, 'David'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1467 values(120, 'Mike'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1467 values(100, 'Chris'); Query OK, 1 row affected (0.12 sec) ... Read More

Do not use the below query for this −insert into yourTableName values(yourValue1, yourValue2, ...N); insert into yourTableName values(yourValue1, yourValue2, ...N); insert into yourTableName values(yourValue1, yourValue2, ...N); . . . NYou can use below query as the fastest way to insert with multiple values in a single query −insert into yourTableName values(yourValue1, yourValue2, ...N), (yourValue1, yourValue2, ...N), (yourValue1, yourValue2, ...N), ...................N;Let us first create a table −mysql> create table DemoTable1466 -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> Name varchar(20),    -> Age int    -> ); Query OK, 0 rows affected (0.98 sec)Insert some records ... Read More

Let us first create a table −mysql> create table DemoTable1465    -> (    -> Name varchar(40)    -> ); Query OK, 0 rows affected (0.54 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1465 values('Chris Brown'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1465 values('David Miller'); Query OK, 1 row affected (0.26 sec) mysql> insert into DemoTable1465 values('John Doe'); Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement −mysql> select * from DemoTable1465;This will produce the following output −+--------------+ | Name         | ... Read More

You can use stored procedure and can pass the value via parameter. Let us first create a table −mysql> create table DemoTable1464    -> (    -> Id int,    -> FirstName varchar(20)    -> ); Query OK, 0 rows affected (0.51 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1464 values(101, 'Chris Brown'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable1464 values(102, 'John Doe'); Query OK, 1 row affected (0.09 sec)Display all records from the table using select statement −mysql> select * from DemoTable1464;This will produce the following output −+------+-------------+ | Id ... Read More

To concatenate multiple rows and columns in single row, you can use GROUP_CONCAT() along with CONCAT(). Let us first create a table −mysql> create table DemoTable1463    -> (    -> ClientId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> ClientName varchar(20),    -> ClientAge int    -> ); Query OK, 0 rows affected (1.37 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1463(ClientName, ClientAge) values('Adam Smith', 34); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1463(ClientName, ClientAge) values('John Doe', 29); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable1463(ClientName, ClientAge) values('David ... Read More

For this, you can use IFNULL() and perform mathematical calculations with NULL and NON-NULL values. Let us first create a table −mysql> create table DemoTable1462    -> (    -> Value1 int,    -> Value2 int    -> ); Query OK, 0 rows affected (0.55 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1462 values(10, 20); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1462 values(50, NULL); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable1462 values(NULL, 70); Query OK, 1 row affected (0.25 sec)Display all records from the table using select ... Read More