For this, use GROUP BY and HAVING. Let us first create a table −mysql> create table DemoTable    (    StudentName varchar(100),    DueDate date    ); Query OK, 0 rows affected (0.72 sec)ExampleInsert some records in the table using insert command −mysql> insert into DemoTable values('John', '2019-01-11'); Query OK, 1 row affected (0.26 sec) mysql> insert into DemoTable values('Chris', '2019-02-11'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values('Chris', '2019-03-11'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('John', '2019-04-11'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('Bob', '2019-05-11'); ... Read More

Yes, an alternative is CONCAT_WS(). Let us first create a table −mysql> create table DemoTable    (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentName varchar(100)    ); Query OK, 0 rows affected (0.74 sec)ExampleInsert some records in the table using insert command −mysql> insert into DemoTable(StudentName) values('Chris'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(StudentName) values('Robert'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(StudentName) values('Bob'); Query OK, 1 row affected (0.12 sec)Display all records from the table using select statement −mysql> select *from DemoTable;Output+-----------+-------------+ | StudentId | StudentName | +-----------+-------------+ | ... Read More

For this, use REPLACE() function and replace empty space with the character. Let us first create a table −mysql> create table DemoTable (Subject text); Query OK, 0 rows affected (0.86 sec)ExampleInsert some records in the table using insert command −mysql> insert into DemoTable values('Introduction to MySQL'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('Java in depth'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('Data Structure and Algorithm'); Query OK, 1 row affected (0.16 sec)Display all records from the table using select statement −mysql> select *from DemoTable;Output+------------------------------+ | Subject | +------------------------------+ | Introduction ... Read More

Use index to select top n rows efficiently. Let us first create a table −mysql> create table DemoTable (StudentName varchar(100), StudentScore int ); Query OK, 0 rows affected (0.66 sec)ExampleInsert some records in the table using insert command −mysql> insert into DemoTable values('John', 34); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('Carol', 55); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('Bob', 58); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('Sam', 38); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Mike', 48); Query OK, 1 row ... Read More

For this, you can use CHAR_LENGTH(). Use RAND() for random records. Let us first create a table −mysql> create table DemoTable (Subject text); Query OK, 0 rows affected (0.61 sec)ExampleInsert some records in the table using insert command −mysql> insert into DemoTable values('C'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('MySQL'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Java'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('MongoDB'); Query OK, 1 row affected (0.59 sec) mysql> insert into DemoTable values('RubyOnRails'); Query OK, 1 row affected (0.25 sec) mysql> insert ... Read More

For this, you can use LAST_INSERT_ID(). Let us first create a table −mysql> create table DemoTable    (    UserId int(6) unsigned zerofill NOT NULL AUTO_INCREMENT,    UserAutoIncrement char(100) default null,    PRIMARY KEY(UserId)    ); Query OK, 0 rows affected (0.72 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(); Query OK, 1 row affected (0.13 sec)Display all records from the table using select statement −mysql> select *from DemoTable;Output+--------+-------------------+ | UserId | UserAutoIncrement | +--------+-------------------+ | 000001 | NULL | +--------+-------------------+ ... Read More

To round seconds to nearest half minute, use CEILING(). Let us first create a table −mysql> create table DemoTable (secondValue int); Query OK, 0 rows affected (0.64 sec)ExampleInsert some records in the table using insert command −mysql> insert into DemoTable values(27); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable values(56); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(118); Query OK, 1 row affected (0.20 sec)Display all records from the table using select statement −mysql> select *from DemoTable;Output+-------------+ | secondValue | +-------------+ | 27          | | 56       ... Read More

PL/SQL stands for “Procedural Language extension to SQL” . It is the mixture of SQL and Procedural features provided by programming language. It was developed by Oracle Corporation in the late 1980s as procedural extension language for SQL and the Oracle relational database.PL/SQL programs consists of blocks that can be nested and a block structure look likes this −DECLARE    -- it contains declaration statements BEGIN    -- It contains executable statements EXCEPTIONS    -- It contains exception handling statements END;ExampleIn PL/SQL single-line comments begin with double hyphen(--) and Multi-line comments begin with a slash-asterisk ( /* ) and end ... Read More

For this, you can use COUNT() function. Let us first create a table −mysql> create table DemoTable    -> (    -> EmployeeId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> EmployeeName varchar(100)    -> ); Query OK, 0 rows affected (0.62 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(EmployeeName) values('John'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable(EmployeeName) values('Carol'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(EmployeeName) values('David'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(EmployeeName) values('Carol'); Query OK, 1 row affected ... Read More

For this, use COALESCE() function from MySQL. Let us first create a table −mysql> create table DemoTable -> ( -> Value1 int, -> Value2 int -> ); Query OK, 0 rows affected (0.51 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(100, 200); Query OK, 1 row affected (0.27 sec) mysql> insert into DemoTable values(NULL, 90); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(NULL, NULL); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(600, NULL); Query OK, 1 row affected (0.12 sec)Display all records from ... Read More