[FLINK-21774][sql-client] Do not display column names when return set…

… is emtpy in SQL Client

flink-table/flink-sql-client/src/test/resources/sql/function.q

@@ -110,8 +110,8 @@ show user functions;
 +---------------+
 | function name |
 +---------------+
-| func4 |
 | func3 |
+| func4 |
 +---------------+
 2 rows in set
 !ok
@@ -173,9 +173,9 @@ show user functions;
 +---------------+
 | function name |
 +---------------+
-| func4 |
 | func11 |
 | func3 |
+| func4 |
 +---------------+
 3 rows in set
 !ok

flink-table/flink-table-api-java/src/main/java/org/apache/flink/table/api/internal/TableEnvironmentImpl.java

@@ -628,12 +628,19 @@ public boolean dropTemporaryView(String path) {
 
  @Override
  public String[] listUserDefinedFunctions() {
- return functionCatalog.getUserDefinedFunctions();
+ return sortFunctions(functionCatalog.getUserDefinedFunctions());
  }
 
  @Override
  public String[] listFunctions() {
- return functionCatalog.getFunctions();
+ return sortFunctions(functionCatalog.getFunctions());
+ }
+
+ private String[] sortFunctions(String[] functions) {
+ if (functions != null && functions.length > 0) {
+ Arrays.sort(functions);
+ }
+ return functions;
  }
 
  @Override

flink-table/flink-table-common/src/main/java/org/apache/flink/table/utils/PrintUtils.java

@@ -116,36 +116,37 @@ public static void printAsTableauForm(
  String nullColumn,
  boolean deriveColumnWidthByType,
  boolean printRowKind) {
- final List<TableColumn> columns = tableSchema.getTableColumns();
- String[] columnNames = columns.stream().map(TableColumn::getName).toArray(String[]::new);
- if (printRowKind) {
- columnNames =
- Stream.concat(Stream.of(ROW_KIND_COLUMN), Arrays.stream(columnNames))
- .toArray(String[]::new);
- }
+ if (it.hasNext()) {
+ final List<TableColumn> columns = tableSchema.getTableColumns();
+ String[] columnNames =
+ columns.stream().map(TableColumn::getName).toArray(String[]::new);
+ if (printRowKind) {
+ columnNames =
+ Stream.concat(Stream.of(ROW_KIND_COLUMN), Arrays.stream(columnNames))
+ .toArray(String[]::new);
+ }
 
- final int[] colWidths;
- if (deriveColumnWidthByType) {
- colWidths =
- columnWidthsByType(
- columns,
- maxColumnWidth,
- nullColumn,
- printRowKind ? ROW_KIND_COLUMN : null);
- } else {
- final List<Row> rows = new ArrayList<>();
- final List<String[]> content = new ArrayList<>();
- content.add(columnNames);
- while (it.hasNext()) {
- Row row = it.next();
- rows.add(row);
- content.add(rowToString(row, nullColumn, printRowKind));
+ final int[] colWidths;
+ if (deriveColumnWidthByType) {
+ colWidths =
+ columnWidthsByType(
+ columns,
+ maxColumnWidth,
+ nullColumn,
+ printRowKind ? ROW_KIND_COLUMN : null);
+ } else {
+ final List<Row> rows = new ArrayList<>();
+ final List<String[]> content = new ArrayList<>();
+ content.add(columnNames);
+ while (it.hasNext()) {
+ Row row = it.next();
+ rows.add(row);
+ content.add(rowToString(row, nullColumn, printRowKind));
+ }
+ colWidths = columnWidthsByContent(columnNames, content, maxColumnWidth);
+ it = rows.iterator();
  }
- colWidths = columnWidthsByContent(columnNames, content, maxColumnWidth);
- it = rows.iterator();
- }
 
- if (it.hasNext()) {
  final String borderline = PrintUtils.genBorderLine(colWidths);
  // print border line
  printWriter.println(borderline);