The length attribute is used to provide the column with a maximum size.

Here is an example:

@Column(name="emp_code", length=100)
private String empCode;

The nullable attribute accepts a Boolean value. If nullable is true, it means that the column contains a NULL value. It does not accept NULL if the value of nullable is set to false, but the default value of nullable is true.

Here is an example:

@Column(name="emp_code", nullable=false)
private String empCode;

The unique attribute also accepts a Boolean value. If unique is set to true, hibernate will create a column with a UNIQUE index. However, the default value is false.

Here is an example:

@Column(name="emp_code", unique=true)
private String empCode;

Here, hibernate creates a UNIQUE index for the "emp_code" column.

This is a useful attribute of the annotation. It accepts a string value. We can give it a SQL fragment, which is used at the time of table creation.

Let's consider a useful example.

If we have a date field and want to set a default date but no date is provided at the time of the insertion of the rows, we can use the following code:

@Column(columnDefinition = "timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP")
private Date startDate;

Hibernate directly uses this string while creating the table.

We will consider scale and precision together for a better understanding.

The precision and scale attributes come into the picture when we have the decimal data type of the column and want to store the value with the decimal point.

Here is an example:

@Column(precision = 7, scale = 2)
private BigDecimal salary;

This will create a salary column with the decimal data type and length 7,2. This means that you can enter a value up to 7 and from among that 2 digit contains decimal part.

Both these attributes accept a Boolean value. This denotes whether the column takes part in the insert and update operations or not.