Using Java to Implement Oracle Aggregated Queries
Using Java to implement various aggregate queries of Oracle, you can connect to Oracle Database through JDBC, and write SQL statements for query operations. The following are the steps to implement various Oracle aggregation queries using Java:
1. By introducing Oracle JDBC driver dependencies, the following dependency coordinates can be added to the pom.xml file of the Maven project:
<dependency>
<groupId>com.oracle.database.jdbc</groupId>
<artifactId>ojdbc8</artifactId>
<version>19.3.0.0</version>
</dependency>
2. Using JDBC to connect to a database in Java code can use the following code:
import java.sql.*;
public class OracleAggregationQuery {
public static void main(String[] args) {
String URL="jdbc: oracle: thin: @ localhost: 1521: xe"// Oracle Database connection URL
String username="your username"// Database username
String password="your password"// Database password
try {
Connection connection = DriverManager.getConnection(url, username, password);
Statement statement = connection.createStatement();
//Write SQL query statements
String SQL="SELECT COUNT (*) From your table"// Taking the COUNT aggregate function as an example
ResultSet resultSet = statement.executeQuery(sql);
if (resultSet.next()) {
int count = resultSet.getInt(1);
System.out.println("Count: " + count);
}
resultSet.close();
statement.close();
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
In the above example, use JDBC to connect to the Oracle Database, execute the COUNT aggregate function query, and print the results.
3. Various aggregation functions such as SUM, AVG, MIN, MAX, etc. can be used as needed, and different SQL query statements can be written.
It should be noted that in practical applications, the parameters (URL, username, and password) for connecting to the database should be modified according to the actual situation.
At the same time, if Maven is used to build the project, you need to ensure that the version of the Oracle JDBC driver matches the version of the Oracle Database.
The above is a brief introduction and sample code for implementing various Oracle aggregation queries using Java. In practical applications, more complex SQL query statements can be written according to specific needs and Java can be used to perform query operations.
