For every single statement on MySQL command line, it shows the exact time to execute the specific statement.Let us first create a table −mysql> create table DemoTable1589    -> (    -> EmployeeId int,    -> EmployeeName varchar(20)    -> ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1589 values(101, 'Sam'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1589 values(102, 'Bob'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable1589 values(103, 'David'); Query OK, 1 row affected (0.16 sec)Display all records from the table ... Read More

To select maximum of sum of two columns, use aggregate function MAX() along with subquery. Let us first create a table −mysql> create table DemoTable1587    -> (    -> Value1 int,    -> Value2 int    -> ); Query OK, 0 rows affected (0.59 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1587 values(30, 50); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1587 values(80, 90); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1587 values(40, 67); Query OK, 1 row affected (0.13 sec)Display all records from the table using select ... Read More

To display information about field names, the syntax is as follows −show columns from yourTableName;Let us first create a table −mysql> create table DemoTable1586    -> (    -> EmployeeId int,    -> EmployeeFirstName varchar(20),    -> EmployeeLastName varchar(20),    -> EmployeeAge int,    -> EmployeeCountryName varchar(20),    -> EmployeeSalary int    -> ); Query OK, 0 rows affected (0.78 sec)Following is the query to display field names −mysql> show columns from DemoTable1586;This will produce the following output −+---------------------+-------------+------+-----+---------+-------+ | Field               | Type        | Null | Key | Default | ... Read More

An error will arise and nothing will get inserted in the table Let us see an example and create a table −mysql> create table DemoTable1585    -> (    -> StudentId int,    -> StudentMarks int,    -> UNIQUE(StudentId)    -> ); Query OK, 0 rows affected (1.02 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1585 values(1,87),(2,98),(3,91),(3,48); ERROR 1062 (23000): Duplicate entry '3' for key 'StudentId'Display all records from the table using select statement −mysql> select * from DemoTable1585;This will produce the following output. Nothing gets inserted:Empty set (0.00 sec)

Triggers are a great feature in MySQL that allows the automation of processes either before or after data has changed in a table. An important application of the usage of triggers is for automatic date addition to the database. This article guides you on how to add the current date in MySQL using triggers every time a new record is being inserted. The following examples uses a BEFORE INSERT trigger in setting a date within a column of a table automatically. BEFORE INSERT trigger This trigger is executed right before a value is inserted into a database table. Whenever ... Read More

To delete partial data, use UPDATE command along with REPLACE(). Let us first create a table −mysql> create table DemoTable1583    -> (    -> GameDetails text    -> ); Query OK, 0 rows affected (1.38 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1583 values('=Candy, 2000'); Query OK, 1 row affected (0.53 sec) mysql> insert into DemoTable1583 values('=Lucky29, 10000'); Query OK, 1 row affected (0.25 sec)Display all records from the table using select statement −mysql> select * from DemoTable1583;This will produce the following output −+------------------------------------------------------------+ | GameDetails                 ... Read More

Let’s say the current date is −'2019-10-20We will first see an example and create a table −mysql> create table DemoTable1582    -> (    -> PostedDate datetime    -> ); Query OK, 0 rows affected (13.36 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1582 values('2019-01-21 12:34:40'); Query OK, 1 row affected (1.06 sec) mysql> insert into DemoTable1582 values('2019-10-15 11:00:00'); Query OK, 1 row affected (0.87 sec) mysql> insert into DemoTable1582 values('2019-10-25 1:10:00'); Query OK, 1 row affected (1.14 sec)Display all records from the table using select statement −mysql> select * from DemoTable1582;This will produce the ... Read More

To ensure that MySQL rows are unique, you need to use UNIQUE constraint. Let us first create a table −mysql> create table DemoTable1580    -> (    -> id int,    -> Name varchar(20),    -> Age int    -> ); Query OK, 0 rows affected (0.73 sec)Here is the query to create unique constraints to ensure MySQL rows are unique −mysql> alter table DemoTable1580 add unique index(id, Name, Age); Query OK, 0 rows affected (0.45 sec) Records: 0  Duplicates: 0  Warnings: 0Insert some records in the table using insert command −mysql> insert into DemoTable1580 values(101, 'Chris', 21); Query OK, ... Read More

To select the last three rows in ascending order, use ORDER BY DESC LIMIT as in the below syntax −select * from (select * from yourTableName order by yourColumnName desc limit 3) anyAliasName order by yourColumnName ;Let us first create a table −mysql> create table DemoTable1579    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> Name varchar(20)    -> ); Query OK, 0 rows affected (0.67 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1579(Name) values('Robert'); Query OK, 1 row affected (0.37 sec) mysql> insert into DemoTable1579(Name) values('Bob'); Query OK, 1 ... Read More

Here is the query to create first table.mysql> create table DemoTable1    -> (    -> StudentName varchar(20),    -> StudentMarks int    -> ); Query OK, 0 rows affected (0.67 sec)To understand the above concept, let us create second table.mysql> create table DemoTable2    -> (    -> Name varchar(20)    -> ); Query OK, 0 rows affected (0.61 sec)Insert some records in the table using insert command −mysql> insert into DemoTable2 values('Chris'); Query OK, 1 row affected (0.12 sec)Display all records from the table using select statement −mysql> select * from DemoTable2;This will produce the following output −+-------+ ... Read More