To add leading zeros, you can use LPAD(). Let us first create a table −mysql> create table DemoTable (    Code varchar(100) ); Query OK, 0 rows affected (0.87 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('JS'); Query OK, 1 row affected (0.15 sec) ... Read More

For this, you can use the DATE() function. Let us first create a table −mysql> create table DemoTable (    Number int ); Query OK, 0 rows affected (0.48 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(20190108); Query OK, 1 row affected (0.11 sec) ... Read More

Let us first create a table −mysql> create table DemoTable (    Number int ); Query OK, 0 rows affected (0.79 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(56); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(78); Query OK, 1 ... Read More

Let us first create a table −mysql> create table DemoTable (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    Name varchar(100) ); Query OK, 0 rows affected (0.55 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Name) values('John Smith'); Query OK, 1 row affected (0.17 ... Read More

Let us first create a table −mysql> create table DemoTable (    Download varchar(100) ); Query OK, 0 rows affected (0.53 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('120 Gigabytes'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('190 Gigabytes'); Query ... Read More

To get a particular varchar ID from a list, you can use FIND_IN_SET(). Let us first create a table −mysql> create table DemoTable (    Id varchar(255) ); Query OK, 0 rows affected (0.51 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('10, 100, 1000'); ... Read More

For this, you can use IS NULL property. Let us first create a table −mysql> create table DemoTable (    ProductPrice int,    ProductQuantity int,    TotalAmount int ); Query OK, 0 rows affected (1.22 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(ProductPrice, ProductQuantity) values(100, ... Read More

To make a pair of columns unique, use UNIQUE with ALTER TABLE command. Following is the syntax −alter table yourTableName add unique yourUniqueName(yourColumnName1, yourColumnName2, ...N);Let us first create a table −mysql> create table DemoTable (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentFirstName varchar(100),    StudentLastName varchar(100),   ... Read More

Let us first see when this situation can arise. Create a table and set column name with datatype but without the size −mysql> create table DemoTable (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    FirstName varchar,    LastName varchar ); ERROR 1064 (42000): You have an error in ... Read More

To use the reserved keyword ‘Key’, use the concept of the backtick symbol. Here, for our example, I am using the column name key which needs a backtick symbol around the column name.Let us first create a table −mysql> create table DemoTable (    `Key` int ); Query OK, 0 ... Read More