Hibernate – Types of Mapping

Hibernate is a Java framework that simplifies the development of Java applications to interact with the database. It is an open-source, lightweight, ORM (Object Relational Mapping) tool. Hibernate implements the specifications of JPA (Java Persistence API) for data persistence.

There are different relations that we maintain to establish a link between different database tables in relational database models. These relations are one to one, one to many, and many to many. A similar concept is being installed in hibernate. Here the hibernate works to link the JAVA language to the database table along with this link we can establish relations/mappings. 

The main basic types of mapping are: 

1. Primitive Types
2. Date and Time Types
3. Binary and Large Object Types
4. JDK-related Types

So, let us discuss each of the above 4 listed mapping types in detail as follows:

A. Primitive Types

These types of mapping have data types defined as “integer”, “character”, “float”, “string”, “double”, “Boolean”, “short”, “long” etc. These are present in hibernate framework to map java data type to RDBMS data type.        

Mapping Type	Java Type	ANSI SQL Type
integer	int or java.lang.Integer	INTEGER
character	java.lang.String	CHAR(1)
float	float or java.lang.Float	FLOAT
string	java.lang.String	VARCHAR
double	double or java.lang.Double	DOUBLE
boolean	boolean or java.lang.Boolean	BIT
short	short or java.lang.Short	SMALLINT
long	long or java.lang.Long	BIGINT
byte	byte or java.lang.Byte	TINYINT
big_decimal	java.math.BigDecimal	NUMERIC

B. Date and Time

These are “date”, “time”, “calendar”, “timestamp” etc. Like primitive we have these date and time datatype mappings.

Mapping type	Java type	ANSI SQL Type
date	java.util.Date or java.sql.Date	DATE
time	java.util.Date or java.sql.Time	TIME
calendar	java.util.Calendar	TIMESTAMP
timestamp	java.util.Date or java.sql.Timestamp	TIMESTAMP
calendar_date	java.util.Calendar	DATE

C. Binary and large objects 

These types are “clob”, “blob”, “binary”, “text” etc. Clob and blob data types are present to maintain the data type mapping of large objects like images and videos.

Mapping type	Java type	ANSI SQL Type
clob	java.sql.Clob	CLOB
blob	java.sql.Blob	BLOB
binary	byte[]	VARBINARY (or BLOB)
text	java.lang.String	CLOB
serializable	any Java class that implements java.io.Serializable	VARBINARY (or BLOB)

D. JDK linked

Some of the mappings for objects which lie beyond the reach of the previous type of mappings are included in this category. These are “class”, “locale”, “currency”, “timezone”.

Mapping type	Java type	ANSI SQL Type
class	java.lang.Class	VARCHAR
locale	java.util.Locale	VARCHAR
currency	java.util.Currency	VARCHAR
timezone	java.util.Currency	VARCHAR

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