You can use REPLACE INTO that works like DELETE + INSERT. Let us first create a table −mysql> create table DemoTable (    Id int,    FirstName varchar(50) ); Query OK, 0 rows affected (0.60 sec)Following is the query to create a unique index −mysql> alter table DemoTable add unique ... Read More

To find the highest and lowest from two tables, use MAX() and MIN(). Since the results are to be displayed from two tables, you need to use UNION. Let us first create a table −mysql> create table DemoTable1 (    UniqueId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    Score1 int ... Read More

If your first column is AUTO_INCREMENT, then you can skip the column and place the value NULL. Let us first create a table −mysql> create table DemoTable (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentFirstName varchar(100),    StudentAge int ); Query OK, 0 rows affected (0.60 sec)Insert ... Read More

To optimize many SELECTs, use it once and apply IN() to fetch multiple values. Let us first create a table −mysql> create table DemoTable (    Id int,    Name varchar(100),    Age int ); Query OK, 0 rows affected (0.77 sec)Insert some records in the table using insert command ... Read More

To count the duplicate ID values, use aggregate function COUNT() and GROUP BY. Let us first create a table −mysql> create table DemoTable (    Id int,    Name varchar(100) ); Query OK, 0 rows affected (1.30 sec)Insert some records in the table using insert command −mysql> insert into DemoTable ... Read More

Let us first create a table −mysql> create table DemoTable1 (    Id int,    Name varchar(100) ); Query OK, 0 rows affected (0.86 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1 values(1001, 'Chris'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1 ... Read More

For this, you can use round() along with avg(). Let us first create a table −mysql> create table DemoTable (    Score int ); Query OK, 0 rows affected (0.68 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(98); Query OK, 1 row affected (0.22 ... Read More

There is no difference between TINYINT(1) and Boolean. The keyword Bool or Boolean internally converts into TINYINT(1) or we can say Bool or Boolean are synonymous with TINYINT(1).Let us first create a table −mysql> create table DemoTable (    isMarried Boolean ); Query OK, 0 rows affected (1.77 sec)Let us ... Read More

For this, use AS select statement. Let us first create a table −mysql> create table DemoTable1 (    Score int ); Query OK, 0 rows affected (1.22 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1 values(89); Query OK, 1 row affected (0.14 sec) mysql> insert ... Read More

To find a minimum score from the entire four columns, use MySQL LEAST() function. Let us first create a table −mysql> create table DemoTable(    Score1 int,    Score2 int,    Score3 int,    Score4 int ); Query OK, 0 rows affected (0.50 sec)Insert some records in the table using ... Read More