To avoid repair with keycache in MySQL, you need to follow the below syntax −create table yourNewTableName as (select *from yourOldTableName); alter table yourNewTableName add index(yourCoumnName);Let us first create a table −mysql> create table DemoTable    (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentFirstName varchar(20),    StudentLastName varchar(20)    ); Query OK, 0 rows affected (0.24 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(StudentFirstName, StudentLastName) values('John', 'Doe'); Query OK, 1 row affected (0.05 sec) mysql> insert into DemoTable(StudentFirstName, StudentLastName) values('David', 'Miller'); Query OK, 1 row affected (0.05 sec)Display all records from ... Read More

Let us first create a table −mysql> create table DemoTable    (    ProductId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    ProductQuantity int,    ProductPrice int    ); Query OK, 0 rows affected (0.19 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(ProductQuantity, ProductPrice) values(10, 100); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(ProductQuantity, ProductPrice) values(5, 11); Query OK, 1 row affected (0.04 sec) mysql> insert into DemoTable(ProductQuantity, ProductPrice) values(3, 140); Query OK, 1 row affected (0.05 sec) mysql> insert into DemoTable(ProductQuantity, ProductPrice) values(2, 450); Query OK, 1 row affected ... Read More

You can use regular expression for this. Let us first create a table −mysql> create table DemoTable    (    ProductId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    ProductName varchar(20)    ); Query OK, 0 rows affected (0.19 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(ProductName) values('Product-1'); Query OK, 1 row affected (0.05 sec) mysql> insert into DemoTable(ProductName) values('Product2'); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(ProductName) values('Product1'); Query OK, 1 row affected (0.04 sec) mysql> insert into DemoTable(ProductName) values('Product-3'); Query OK, 1 row affected (0.05 sec) mysql> ... Read More

Let us first create a table −mysql> create table DemoTable    (    UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    UserFirstName varchar(20),    UserLastName varchar(20),    UserAge int,    UserCountryName varchar(20)    ); Query OK, 0 rows affected (0.27 sec)Now check the description of table.mysql> desc DemoTable;This will produce the following output −+-----------------+-------------+------+-----+---------+----------------+ | Field           | Type        | Null | Key | Default | Extra | +-----------------+-------------+------+-----+---------+----------------+ | UserId          | int(11)     | NO   | PRI ... Read More

Use HAVING to find all columns where the column name length is greater than 5. This will produce the following output −+-------------------+-------------------------+ | TABLE_NAME        | COLUMN_NAME             | +-------------------+-------------------------+ | DemoTable         | UserId                  | | DemoTable         | EndDate                 | | DemoTable         | StartDate               | | DemoTable         | StudentFavouriteSubject | | DemoTable     ... Read More

Following is the query to create a stored procedure that creates a table. Here, we are creating a table with three columns, one of them is Id −mysql> DELIMITER //    mysql> CREATE PROCEDURE Stored_Procedure_CreatingTable()    BEGIN       create table DemoTable       (       Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,       UserFirstName varchar(20),       UserLastName varchar(20)       );    END;    //    Query OK, 0 rows affected (0.16 sec) mysql> DELIMITER ;Now you can call stored procedure with the help of CALL command −mysql> call Stored_Procedure_CreatingTable(); ... Read More

To count common elements, use COUNT() and GROUP BY. Let us first create a table −mysql> create table DemoTable    (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    Number int    ); Query OK, 0 rows affected (0.20 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Number) values(10); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(Number) values(20); Query OK, 1 row affected (0.04 sec) mysql> insert into DemoTable(Number) values(20); Query OK, 1 row affected (0.04 sec) mysql> insert into DemoTable(Number) values(30); Query OK, 1 row affected (0.04 sec) ... Read More

To count presence of a NOT NULL value, use aggregate function COUNT(yourColumnName). Let us first create a table −mysql> create table DemoTable    (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    NumberOfQuestion int,    NumberOfSolution int    ); Query OK, 0 rows affected (0.20 sec)Insert some records in the table using insert command. Here, some of the values are NULL −mysql> insert into DemoTable(NumberOfQuestion, NumberOfSolution) values(20, 10); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(NumberOfQuestion, NumberOfSolution) values(20, 2); Query OK, 1 row affected (0.04 sec) mysql> insert into DemoTable(NumberOfQuestion, NumberOfSolution) values(20, NULL); Query ... Read More

For this, use subquery along with HAVING clause. Let us first create a table −mysql> create table DemoTable    (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentFirstName varchar(20),    StudentLastName varchar(20)    ); Query OK, 0 rows affected (0.27 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(StudentFirstName, StudentLastName) values('John', 'Smith'); Query OK, 1 row affected (0.04 sec) mysql> insert into DemoTable(StudentFirstName, StudentLastName) values('Carol', 'Taylor'); Query OK, 1 row affected (0.04 sec) mysql> insert into DemoTable(StudentFirstName, StudentLastName) values('John', 'Doe'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(StudentFirstName, ... Read More

Use CHAR_LENGTH(yourColumnName) at the time of table creation. Let us first see an example and create a table −mysql> create table DemoTable    (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    Title varchar(200),    `Number_of_characters` int as (char_length(Title))    ); Query OK, 0 rows affected (0.18 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Title) values('Introduction To MySQL'); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(Title) values('Introduction To Java'); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(Title) values('Introduction To MongoDB'); Query OK, 1 row affected (0.04 ... Read More