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:
- Primitive Types
- Date and Time Types
- Binary and Large Object Types
- 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 |
