PLJAVA inout postgresql
时间: 2023-06-21 21:08:50 浏览: 53
PL/Java is an extension for PostgreSQL that allows you to write stored procedures, functions, and triggers in Java. It provides a way to integrate Java code into your database, making it possible to perform complex calculations and data manipulations inside the database itself.
To handle input and output in PL/Java, you can use the Java Database Connectivity (JDBC) API. This allows you to connect to the database, execute SQL statements, and retrieve results. Here is an example of a PL/Java function that takes an input parameter and returns a result:
```java
import java.sql.*;
public class MyFunctions {
public static int add(int a, int b) throws SQLException {
Connection conn = DriverManager.getConnection("jdbc:postgresql://localhost/mydatabase", "myuser", "mypassword");
PreparedStatement stmt = conn.prepareStatement("SELECT ? + ?");
stmt.setInt(1, a);
stmt.setInt(2, b);
ResultSet rs = stmt.executeQuery();
rs.next();
int result = rs.getInt(1);
rs.close();
stmt.close();
conn.close();
return result;
}
}
```
In this example, the `add` function takes two integer parameters (`a` and `b`) and returns their sum. It uses JDBC to connect to the database, execute a SQL statement that adds the two parameters, and retrieve the result. Finally, it closes the database resources and returns the result.
To use this function in PostgreSQL, you need to install the PL/Java extension and create a Java function that calls the `add` method:
```sql
CREATE FUNCTION my_add(int, int)
RETURNS int
AS 'MyFunctions.add'
LANGUAGE java;
```
Now you can use the `my_add` function in your SQL queries:
```sql
SELECT my_add(1, 2); -- returns 3
```