add example.

Author: youngsofun

databend-jdbc/src/main/java/com/databend/jdbc/examples/LoadToTableFromStream.java

@@ -0,0 +1,57 @@
+package com.databend.jdbc.examples;
+
+import com.databend.jdbc.DatabendConnection;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.sql.*;
+
+public class LoadToTableFromStream {
+    public static void main(String[] args) throws SQLException {
+        uploadAndCopy();
+    }
+
+    static void uploadAndCopy() throws SQLException {
+        // assuming the file and stage1 and table1 already exist
+        String filePath = "data.csv";
+
+        String stageName = "stage1";
+        String prefix = "data_set1";
+        String fileName = "data1";
+        String path = "@stage1/data_set1/data1";
+
+        String url = "jdbc:databend://localhost:8000";
+        try(Connection conn = DriverManager.getConnection(url, "databend", "databend");
+            Statement stmt = conn.createStatement())  {
+
+            // upload
+            InputStream inputStream = Files.newInputStream(Paths.get(filePath));
+            long fileSize = Files.size(Paths.get("data.csv"));
+            DatabendConnection databendConnection = conn.unwrap(DatabendConnection.class);
+            databendConnection.uploadStream(inputStream, stageName, prefix, fileName, fileSize, false);
+
+            // optional list
+            String sql = String.format("list %s", path);
+            try(ResultSet rs = stmt.executeQuery(sql)) {
+                while (rs.next()) {
+                    System.out.println(rs.getString(1));
+                }
+            }
+
+            // copy into table
+            // https://docs.databend.com/sql/sql-commands/dml/dml-copy-into-table
+            sql = String.format("copy into table1 from %s file_format =(type=csv) purge=true", path);
+            try(ResultSet rs = stmt.executeQuery(sql)) {
+                while (rs.next()) {
+                    System.out.println( rs.getString("ROWS_LOADED") + ", " +
+                            rs.getInt("ROWS_LOADED") + ", " +
+                            rs.getInt("ERRORS_SEEN"));
+                }
+            }
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}