chore: add jdbc demo

GreptimeTeam · Jan 9, 2024 · e644bfd · e644bfd
1 parent 2063fe6
commit e644bfd
Showing 1 changed file with 53 additions and 1 deletion.
diff --git a/ingester-example/src/main/java/io/greptime/QueryJDBC.java b/ingester-example/src/main/java/io/greptime/QueryJDBC.java
@@ -15,26 +15,65 @@
  */
 package io.greptime;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import java.io.IOException;
 import java.sql.Connection;
 import java.sql.DriverManager;
+import java.sql.ResultSet;
 import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Objects;
 import java.util.Properties;
+import java.util.concurrent.ExecutionException;
 
 /**
  * @author jiachun.fjc
  */
 public class QueryJDBC {
 
+    private static final Logger LOG = LoggerFactory.getLogger(QueryJDBC.class);
+
     public static void main(String[] args) throws Exception {
         GreptimeDB greptimeDB = TestConnector.connectToDefaultDB();
 
         // Inserts data first
-
+        insertData(greptimeDB);
 
         try (Connection conn = makeConnection()) {
+            Statement statement = conn.createStatement();
+
+            // DESC table;
+            ResultSet rs = statement.executeQuery("DESC cpu_metric");
+            LOG.info("Column | Type | Key | Null | Default | Semantic Type ");
+            while (rs.next()) {
+                LOG.info("{} | {} | {} | {} | {} | {}", //
+                        rs.getString(1), //
+                        rs.getString(2), //
+                        rs.getString(3), //
+                        rs.getString(4), //
+                        rs.getString(5), //
+                        rs.getString(6));
+            }
+
+            // SELECT COUNT(*) FROM cpu_metric;
+            rs = statement.executeQuery("SELECT COUNT(*) FROM cpu_metric");
+            while (rs.next()) {
+                LOG.info("Count: {}", rs.getInt(1));
+            }
 
+            // SELECT * FROM cpu_metric ORDER BY ts DESC LIMIT 5;
+            rs = statement.executeQuery("SELECT * FROM cpu_metric ORDER BY ts DESC LIMIT 5");
+            LOG.info("host | ts | cpu_user | cpu_sys");
+            while (rs.next()) {
+                LOG.info("{} | {} | {} | {}", //
+                        rs.getString("host"), //
+                        rs.getTimestamp("ts"), //
+                        rs.getDouble("cpu_user"), //
+                        rs.getDouble("cpu_sys"));
+            }
         }
     }
 
@@ -53,4 +92,17 @@ public static Connection makeConnection() throws IOException, ClassNotFoundExcep
 
         return Objects.requireNonNull(dbConn, "Failed to make connection!");
     }
+
+    public static void insertData(GreptimeDB greptimeDB) throws ExecutionException, InterruptedException {
+        List<Cpu> cpus = new ArrayList<>();
+        for (int i = 0; i < 10; i++) {
+            Cpu c = new Cpu();
+            c.setHost("127.0.0." + i);
+            c.setTs(System.currentTimeMillis());
+            c.setCpuUser(i + 0.1);
+            c.setCpuSys(i + 0.12);
+            cpus.add(c);
+        }
+        greptimeDB.writePOJOs(cpus).get();
+    }
 }