Change catalog/schema in JDBC driver for USE statement

CHANGELOG.md

@@ -11,6 +11,7 @@
 * incorrect algorithm extracted from PEM. [#1274](https://github.com/ClickHouse/clickhouse-java/issues/1274)
 * transaction failure introduced 0.4.0.
 * respect node-specific credentials. [#1114](https://github.com/ClickHouse/clickhouse-java/issues/1114)
+* USE statement does nothing. [#1160](https://github.com/ClickHouse/clickhouse-java/issues/1160)
 
 ## 0.4.1, 2023-02-19
 ### Breaking Changes

clickhouse-jdbc/src/main/java/com/clickhouse/jdbc/ClickHouseConnection.java

@@ -181,6 +181,14 @@ default PreparedStatement prepareStatement(String sql, int resultSetType, int re
      */
     String getCurrentDatabase();
 
+    /**
+     * Sets current database.
+     *
+     * @param database non-empty database name
+     * @throws SQLException when failed to change current database
+     */
+    void setCurrentDatabase(String database) throws SQLException;
+
     /**
      * Gets current user.
      *

clickhouse-jdbc/src/main/java/com/clickhouse/jdbc/internal/ClickHouseConnectionImpl.java

@@ -261,17 +261,6 @@ protected List<ClickHouseColumn> getTableColumns(String dbName, String tableName
         return list;
     }
 
-    protected void setDatabase(String db) throws SQLException {
-        ensureOpen();
-
-        if (db == null || db.isEmpty()) {
-            throw new SQLException("Non-empty database name is required", SqlExceptionUtils.SQL_STATE_INVALID_SCHEMA);
-        } else if (!db.equals(database)) {
-            this.database = db;
-            clientRequest.use(db);
-        }
-    }
-
     protected String getDatabase() throws SQLException {
         ensureOpen();
 
@@ -570,7 +559,7 @@ public boolean isReadOnly() throws SQLException {
     @Override
     public void setCatalog(String catalog) throws SQLException {
         if (jdbcConf.useCatalog()) {
-            setDatabase(catalog);
+            setCurrentDatabase(catalog);
         } else {
             log.warn(
                     "setCatalog method is no-op. Please either change databaseTerm to catalog or use setSchema method instead");
@@ -964,7 +953,7 @@ public Properties getClientInfo() throws SQLException {
     @Override
     public void setSchema(String schema) throws SQLException {
         if (jdbcConf.useSchema()) {
-            setDatabase(schema);
+            setCurrentDatabase(schema);
         } else {
             log.warn(
                     "setSchema method is no-op. Please either change databaseTerm to schema or use setCatalog method instead");
@@ -1033,6 +1022,19 @@ public String getCurrentDatabase() {
         return database;
     }
 
+    @Override
+    public void setCurrentDatabase(String db) throws SQLException {
+        ensureOpen();
+
+        if (db == null || db.isEmpty()) {
+            throw new SQLException("Non-empty database name is required", SqlExceptionUtils.SQL_STATE_INVALID_SCHEMA);
+        } else if (!db.equals(database)) {
+            this.database = db;
+            // TODO execute a simple query to validate if the database exists or not
+            clientRequest.use(db);
+        }
+    }
+
     @Override
     public String getCurrentUser() {
         return user;

clickhouse-jdbc/src/main/java/com/clickhouse/jdbc/internal/ClickHouseStatementImpl.java

@@ -133,7 +133,10 @@ protected void ensureOpen() throws SQLException {
     }
 
     protected ClickHouseResponse processSqlStatement(ClickHouseSqlStatement stmt) throws SQLException {
-        if (stmt.isTCL()) {
+        if (stmt.getStatementType() == StatementType.USE) {
+            connection.setCurrentDatabase(stmt.getDatabaseOrDefault(connection.getCurrentDatabase()));
+            return ClickHouseResponse.EMPTY;
+        } else if (stmt.isTCL()) {
             if (stmt.containsKeyword(ClickHouseTransaction.COMMAND_BEGIN)) {
                 connection.begin();
             } else if (stmt.containsKeyword(ClickHouseTransaction.COMMAND_COMMIT)) {

clickhouse-jdbc/src/test/java/com/clickhouse/jdbc/ClickHouseStatementTest.java

@@ -208,6 +208,20 @@ public void testSwitchCatalog() throws SQLException {
             Assert.assertTrue(rs.next());
             Assert.assertEquals(rs.getString(1), dbName);
             Assert.assertFalse(rs.next());
+
+            conn.createStatement().execute("use system");
+            Assert.assertEquals(conn.getCurrentDatabase(), "system");
+            rs = conn.createStatement().executeQuery("select currentDatabase()");
+            Assert.assertTrue(rs.next());
+            Assert.assertEquals(rs.getString(1), "system");
+            Assert.assertFalse(rs.next());
+
+            conn.createStatement().execute("use `" + dbName + "`");
+            Assert.assertEquals(conn.getCurrentDatabase(), dbName);
+            rs = conn.createStatement().executeQuery("select currentDatabase()");
+            Assert.assertTrue(rs.next());
+            Assert.assertEquals(rs.getString(1), dbName);
+            Assert.assertFalse(rs.next());
         }
     }
 
@@ -243,6 +257,20 @@ public void testSwitchSchema() throws SQLException {
             Assert.assertTrue(rs.next());
             Assert.assertEquals(rs.getString(1), dbName);
             Assert.assertFalse(rs.next());
+
+            conn.createStatement().execute("use system");
+            Assert.assertEquals(conn.getCurrentDatabase(), "system");
+            rs = conn.createStatement().executeQuery("select currentDatabase()");
+            Assert.assertTrue(rs.next());
+            Assert.assertEquals(rs.getString(1), "system");
+            Assert.assertFalse(rs.next());
+
+            conn.createStatement().execute("use `" + dbName + "`");
+            Assert.assertEquals(conn.getCurrentDatabase(), dbName);
+            rs = conn.createStatement().executeQuery("select currentDatabase()");
+            Assert.assertTrue(rs.next());
+            Assert.assertEquals(rs.getString(1), dbName);
+            Assert.assertFalse(rs.next());
         }
     }