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JPA uses the findBy method to customize the query

Recently, spring boot+jpa has been used in the project to access the database. For example, the foreign key course details ID is included in the course catalogue details table in this project. You want to find out all the related course catalog details through the course details ID.

Use findBy method to customize query in JPA

The interface for testing the request in postman is as follows

In this way, it is very convenient to query the required data without having to write the interface to filter it.

FindBy syntax collation prerequisite operation of JPA

Create a persistent entity class

Dao layer inherits JpaRepository

T: entity class

ID: the primary key type of the entity class

Example:

Keywords supported in public interface SysUserRespository extends JpaRepository {} JPA

And: equivalent to the and keyword in SQL, such as findByUsernameAndPassword (String user, Striang pwd)

Or: equivalent to the or keyword in SQL, such as findByUsernameOrAddress (String user, String addr)

Between: equivalent to the between keyword in SQL, such as findBySalaryBetween (int max, int min)

LessThan: equivalent to "" in SQL, such as findBySalaryGreaterThan (int min)

IsNull: equivalent to "is null" in SQL, such as findByUsernameIsNull ()

IsNotNull: equivalent to "is not null" in SQL, such as findByUsernameIsNotNull ()

NotNull: equivalent to IsNotNull

Like: equivalent to "like" in SQL, such as findByUsernameLike (String user)

NotLike: equivalent to "not like" in SQL, such as findByUsernameNotLike (String user)

OrderBy: equivalent to "order by" in SQL, such as findByUsernameOrderBySalaryAsc (String user)

Not: equivalent to "! =" in SQL, such as findByUsernameNot (String user)

In: equivalent to "in" in SQL, such as findByUsernameIn (Collection userList). The parameters of the method can be of type Collection, array or indefinite length.

NotIn: equivalent to "not in" in SQL, such as findByUsernameNotIn (Collection userList). The parameters of the method can be of type Collection, array or indefinite length.

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