From 7f09cc80989de3c23134fbc5508a471db434ae4d Mon Sep 17 00:00:00 2001
From: Dmitry Aleksandrov <dm.blink19@gmail.com>
Date: Tue, 20 May 2025 01:32:40 +0300
Subject: [PATCH] Fix `ResultSet#findColumn` - return actual column's index
 instead of 0

---
 .../client/api/metadata/TableSchema.java      | 13 +++++++
 .../com/clickhouse/jdbc/ResultSetImpl.java    |  2 +-
 .../clickhouse/jdbc/ResultSetImplTest.java    | 38 +++++++++++++++++++
 3 files changed, 52 insertions(+), 1 deletion(-)
 create mode 100644 jdbc-v2/src/test/java/com/clickhouse/jdbc/ResultSetImplTest.java

diff --git a/client-v2/src/main/java/com/clickhouse/client/api/metadata/TableSchema.java b/client-v2/src/main/java/com/clickhouse/client/api/metadata/TableSchema.java
index 8a1589532..ef41832de 100644
--- a/client-v2/src/main/java/com/clickhouse/client/api/metadata/TableSchema.java
+++ b/client-v2/src/main/java/com/clickhouse/client/api/metadata/TableSchema.java
@@ -104,10 +104,23 @@ public String columnIndexToName(int index) {
         return indexToName(index - 1);
     }
 
+    /**
+     * Takes column name and return corresponding index (starting from 1).
+     * Equals to {@code nameToIndex(name) + 1}.
+     *
+     * @param name - column name
+     * @return - column index starting from 1
+     */
     public int nameToColumnIndex(String name) {
         return nameToIndex(name) + 1;
     }
 
+    /**
+     * Takes column name and return corresponding index (starting from 0).
+     *
+     * @param name - column name
+     * @return - column index starting from 0
+     */
     public int nameToIndex(String name) {
         Integer index = colIndex.get(name);
         if (index == null) {
diff --git a/jdbc-v2/src/main/java/com/clickhouse/jdbc/ResultSetImpl.java b/jdbc-v2/src/main/java/com/clickhouse/jdbc/ResultSetImpl.java
index 5e51f4533..f1e356f9b 100644
--- a/jdbc-v2/src/main/java/com/clickhouse/jdbc/ResultSetImpl.java
+++ b/jdbc-v2/src/main/java/com/clickhouse/jdbc/ResultSetImpl.java
@@ -469,7 +469,7 @@ public Object getObject(String columnLabel) throws SQLException {
     public int findColumn(String columnLabel) throws SQLException {
         checkClosed();
         try {
-            return reader.getSchema().getColumnByName(columnLabel).getColumnIndex();
+            return reader.getSchema().nameToColumnIndex(columnLabel);
         } catch (Exception e) {
             throw ExceptionUtils.toSqlState(String.format("Method: findColumn(\"%s\") encountered an exception.", columnLabel), String.format("SQL: [%s]", parentStatement.getLastStatementSql()), e);
         }
diff --git a/jdbc-v2/src/test/java/com/clickhouse/jdbc/ResultSetImplTest.java b/jdbc-v2/src/test/java/com/clickhouse/jdbc/ResultSetImplTest.java
new file mode 100644
index 000000000..ebdc94a3b
--- /dev/null
+++ b/jdbc-v2/src/test/java/com/clickhouse/jdbc/ResultSetImplTest.java
@@ -0,0 +1,38 @@
+package com.clickhouse.jdbc;
+
+import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertTrue;
+
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+import org.testng.annotations.Test;
+
+public class ResultSetImplTest extends JdbcIntegrationTest {
+
+    @Test(groups = "integration")
+    public void shouldReturnColumnIndex() throws SQLException {
+        runQuery("CREATE TABLE rs_test_data (id UInt32, val UInt8) ENGINE = MergeTree ORDER BY (id)");
+        runQuery("INSERT INTO rs_test_data VALUES (1, 10), (2, 20)");
+
+        try (Connection conn = getJdbcConnection()) {
+            try (Statement stmt = conn.createStatement()) {
+                try (ResultSet rs = stmt.executeQuery("SELECT * FROM rs_test_data ORDER BY id")) {
+                    assertTrue(rs.next());
+                    assertEquals(rs.findColumn("id"), 1);
+                    assertEquals(rs.getInt(1), 1);
+                    assertEquals(rs.findColumn("val"), 2);
+                    assertEquals(rs.getInt(2), 10);
+
+                    assertTrue(rs.next());
+                    assertEquals(rs.findColumn("id"), 1);
+                    assertEquals(rs.getInt(1), 2);
+                    assertEquals(rs.findColumn("val"), 2);
+                    assertEquals(rs.getInt(2), 20);
+                }
+            }
+        }
+    }
+}