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For this, use GROUP BY HAVING clause.Let us first create a table −mysql> create table DemoTable782 ( Name varchar(100), Score int ); Query OK, 0 rows affected (1.18 sec)Insert some records in the table using insert command −mysql> insert into DemoTable782 values('John', 156); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable782 values('Carol', 250); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable782 values('Bob', 140); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable782 values('John', 126); Query OK, 1 row affected (0.29 sec) mysql> insert into DemoTable782 values('John', ... Read More
Let us first create a table −mysql> create table DemoTable781 ( Name varchar(100) ); Query OK, 0 rows affected (0.66 sec)Insert some records in the table using insert command −mysql> insert into DemoTable781 values(''); Query OK, 1 row affected (0.29 sec) mysql> insert into DemoTable781 values('Chris'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable781 values(''); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable781 values(null); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable781 values(null); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable781 values(''); Query OK, 1 ... Read More
To exclude some of the column names, use NOT IN.Let us first create a table −mysql> create table DemoTable780 ( CustomerId int, CustomerName varchar(100), CustomerAge int, CustomerCountryName varchar(100), isMarried tinyint(1) ); Query OK, 0 rows affected (0.47 sec)Here is the query to exclude result −mysql> select group_concat(column_name) from `information_schema`.`COLUMNS` m where table_schema = 'web' and table_name = 'DemoTable780' and column_name not in ('CustomerId','CustomerCountryName') group by table_schema,table_name;This will produce the following output -+------------------------------------+ | group_concat(column_name) | +------------------------------------+ | CustomerName,CustomerAge,isMarried | +------------------------------------+ 1 row in set (0.01 sec)
Since the column value ‘ADD’ is already a reserved word, therefore you need to use backticks around the word ADD like `ADD`.Let us see an example and create a table −mysql> create table DemoTable779 ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, `ADD` int ); Query OK, 0 rows affected (0.47 sec)Insert some records in the table using insert command −mysql> insert into DemoTable779(`ADD`) values(54); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable779(`ADD`) values(89); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable779(`ADD`) values(66); Query OK, 1 row affected ... Read More
Generics is a concept in Java where you can enable a class, interface and, method, accept all (reference) types as parameters. In other words it is the concept which enables the users to choose the reference type that a method, constructor of a class accepts, dynamically. By defining a class as generic you are making it type-safe i.e. it can act up on any datatype.To define a generic class you need to specify the type parameter you are using in the angle brackets “” after the class name and you can treat this as datatype of the instance variable an ... Read More
Let us first create a table −mysql> create table DemoTable778 ( ClientId varchar(100), ClientName varchar(100) ); Query OK, 0 rows affected (1.05 sec)Insert some records in the table using insert command −mysql> insert into DemoTable778 values('J-101', 'John'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable778 values('A-102', 'Adam'); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable778 values('C-103', 'Chris'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable778 values('D-104', 'David'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable778 values('R-105', 'Robert'); Query OK, 1 row affected ... Read More
Let us first create a table −mysql> create table DemoTable777 ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentName varchar(100), StudentAge int ); Query OK, 0 rows affected (1.34 sec)Insert some records in the table using insert command −mysql> insert into DemoTable777(StudentName, StudentAge) values('Chris', 23); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable777(StudentName, StudentAge) values('Robert', 21); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable777(StudentName, StudentAge) values('Mike', 19); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable777(StudentName, StudentAge) values('Bob', 22); Query OK, 1 row ... Read More
Let’s say you have set column values as unique key and try to insert duplicate values in the table. This will lead to ERROR 1062 (23000): Duplicate entry.Let us first create a table -mysql> create table DemoTable776 ( FirstValue int, SecondValue int, unique key(FirstValue, SecondValue) ); Query OK, 0 rows affected (0.74 sec)Insert some records in the table using insert command. While inserting duplicate value, the same error arises as shown below -mysql> insert into DemoTable776 values(10, 20); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable776 values(10, 40); Query OK, 1 row affected (0.15 ... Read More
Similar to generic classes you can also define generic methods in Java. These methods use their own type parameters. Just like local variables, the scope of the type parameters of the methods lies within the method.While defining a generic method you need to specify the type parameter within the angle brackets (< T >). This should be placed before the method's return type.You can have multiple type parameters separated by commas. A type parameter, also known as a type variable, is an identifier that specifies a generic type name.The type parameters can be used to declare the return type and ... Read More
Generics is a concept in Java where you can enable a class, interface and, method, accept all (reference) types as parameters. In other words it is the concept which enables the users to choose the reference type that a method, constructor of a class accepts, dynamically. By defining a class as generic you are making it type-safe i.e. it can act up on any data type.Example Live Democlass Student{ T age; Student(T age){ this.age = age; } public void display() { System.out.println("Value of age: "+this.age); } } public class GenericsExample ... Read More