Hi,
Today
we will discuss some of the basic JPA annotations.
Annotations
:-
- @Table
- @Column
- @Temporal
- @Transient
Lets
consider below table -Company
SNO
|
MAIL
|
|
|---|---|---|
1
|
|
|
2
|
|
|
3
|
|
|
1.@Table :-is used to map your entity java bean with the table
In general
your table name and entity bean will have same name at that time
there is no need to use @Table
If the Entity bean is different from
the table name we map it by using @Table annotation
Example :-
Lets take the above table-Company
,but my entity bean name is named as Organization then we can use @Table to map them
@Entity
@Table(name="Company")
Public class
Organization{.......}
2.@Column
:- is used to map an instance variable with a column in a table
If the variable name and
database column name is same ,then there is no need to use column
This is similar to @Table
Example :-
Lets take the data base column
-Name in the above table
In Entity bean we have
companyName.so how to map them?
@Column(name="Name")
Private String companyName;
3.@Temporal :-
- In Java we have java.util.Date and java.util.Calendar classes,if we wnat to persist them into data base we should use @Temporal
- Temporal are set of time based types
Example
:-
@Temporal(TemporalType.DATE)
Date currentDate;
In Entity Mapped to data base
|
|
|
|
|
|
4.@Transient :-
- Attributes that are part of Entity but should not be persisted should be marked as @Transient
- Suppose we have a attribute lastName and should not be persisted to data base,we use@Transient
Example
:-
@Transient
private String lastName;
There are many annotations in
JPA,each one of them has special functionality which i will discuss
in my later posts
Happy
Learning
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me @ sudheer@javarecent.com
or admin@java-recent.com
