fix: render single spaces in DROP PRIMARY KEY, RENAME TABLE and indexes (#2792)

DROP PRIMARY KEY ended with a space, which doubled before CASCADE or
RESTRICT. RENAME TABLE rendered two spaces before the first table, and
an index without a type rendered a leading space, so ALTER TABLE ... ADD
INDEX and named-only indexes came out with doubled spaces. Separate
these words with exactly one space; the SQL is otherwise unchanged.

Signed-off-by: minleejae <mmj9808@gmail.com>

Author: minleejae

src/main/java/net/sf/jsqlparser/statement/alter/AlterExpression.java

@@ -1421,7 +1421,7 @@ protected void toStringRename(StringBuilder b) {
     protected void toStringDropSpecial(StringBuilder b) {
         switch (operation) {
             case DROP_PRIMARY_KEY:
-                b.append("DROP PRIMARY KEY ");
+                b.append("DROP PRIMARY KEY");
                 break;
             case DROP_UNIQUE:
                 b.append("DROP UNIQUE (").append(PlainSelect.getStringList(dropColumns))

src/main/java/net/sf/jsqlparser/statement/alter/RenameTableStatement.java

@@ -125,8 +125,9 @@ public StringBuilder appendTo(StringBuilder builder) {
             if (i == 0) {
                 builder
                         .append("RENAME")
-                        .append(usingTableKeyword ? " TABLE " : " ")
-                        .append(usingIfExistsKeyword ? " IF EXISTS " : " ")
+                        .append(usingTableKeyword ? " TABLE" : "")
+                        .append(usingIfExistsKeyword ? " IF EXISTS" : "")
+                        .append(' ')
                         .append(e.getKey())
                         .append(waitDirective != null && waitDirective.length() > 0
                                 ? " " + waitDirective

src/main/java/net/sf/jsqlparser/statement/create/table/Index.java

@@ -220,21 +220,31 @@ public void appendTo(StringBuilder sql, Consumer<Expression> expressionPrinter)
     }
 
     private void appendDeclarationTo(StringBuilder sql) {
-        String keyword = indexKeyword != null && (type == null
-                || !type.toUpperCase(java.util.Locale.ROOT)
-                        .endsWith(indexKeyword.toUpperCase(java.util.Locale.ROOT)))
-                                ? " " + indexKeyword
-                                : "";
-        sql.append(type != null ? type : "").append(keyword);
+        int start = sql.length();
+        if (type != null) {
+            sql.append(type);
+        }
+        if (indexKeyword != null && (type == null || !type.toUpperCase(java.util.Locale.ROOT)
+                .endsWith(indexKeyword.toUpperCase(java.util.Locale.ROOT)))) {
+            appendWord(sql, start, indexKeyword);
+        }
         if (!name.isEmpty()) {
-            sql.append(' ').append(getName());
+            appendWord(sql, start, getName());
         }
         if (getUsing() != null) {
-            sql.append(" USING ").append(getUsing());
+            appendWord(sql, start, "USING " + getUsing());
         }
         sql.append(nullsDistinctClause()).append(clusteringClause());
     }
 
+    /** Separates {@code word} from earlier declaration words, without a leading space. */
+    private static void appendWord(StringBuilder sql, int start, String word) {
+        if (sql.length() > start) {
+            sql.append(' ');
+        }
+        sql.append(word);
+    }
+
     private void appendColumnsAndSpecTo(StringBuilder sql,
             Consumer<Expression> expressionPrinter) {
         String spec = PlainSelect.getStringList(getIndexSpec(), false, false);

src/test/java/net/sf/jsqlparser/statement/alter/AlterConstraintSeparationTest.java

@@ -50,7 +50,7 @@ void uniqueConstraintAndOrdinaryIndexHaveSeparateEditableDefinitions() throws Ex
         indexAction.getIndex().setName("new_ix");
         assertRoundTrip(statement,
                 "ALTER TABLE t ADD CONSTRAINT unique_symbol UNIQUE INDEX legacy_uq (new_id), "
-                        + "ADD  INDEX new_ix (other)",
+                        + "ADD INDEX new_ix (other)",
                 Dialect.MYSQL);
     }
 
@@ -98,7 +98,7 @@ void replacingDefinitionChangesTheRenderedActionAndItsClassification() throws Ex
         assertNull(action.getConstraint());
         action.setConstraint(null);
         assertEquals(ConstraintKind.OTHER, action.getConstraintKind());
-        assertRoundTrip(statement, "ALTER TABLE t ADD  INDEX ix_new (id)", Dialect.MYSQL);
+        assertRoundTrip(statement, "ALTER TABLE t ADD INDEX ix_new (id)", Dialect.MYSQL);
     }
 
     @ParameterizedTest
@@ -116,7 +116,7 @@ void replacingLegacyUniqueDefinitionClearsItsOldHeader(boolean replaceWithIndex)
                     .withName("ix").withColumnsNames(List.of("id")));
             assertNull(action.getConstraint());
             assertEquals(ConstraintKind.OTHER, action.getConstraintKind());
-            assertRoundTrip(statement, "ALTER TABLE t ADD  INDEX ix (id)", Dialect.MYSQL);
+            assertRoundTrip(statement, "ALTER TABLE t ADD INDEX ix (id)", Dialect.MYSQL);
         } else {
             action.setConstraint(new CheckConstraint()
                     .withExpression(CCJSqlParserUtil.parseCondExpression("id > 0")));

src/test/java/net/sf/jsqlparser/statement/alter/DeparseWhitespaceTest.java

@@ -0,0 +1,56 @@
+/*-
+ * #%L
+ * JSQLParser library
+ * %%
+ * Copyright (C) 2004 - 2026 JSQLParser
+ * %%
+ * Dual licensed under GNU LGPL 2.1 or Apache License 2.0
+ * #L%
+ */
+package net.sf.jsqlparser.statement.alter;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import net.sf.jsqlparser.JSQLParserException;
+import net.sf.jsqlparser.parser.AbstractJSqlParser.Dialect;
+import net.sf.jsqlparser.parser.CCJSqlParserUtil;
+import net.sf.jsqlparser.statement.Statement;
+import net.sf.jsqlparser.statement.create.table.Index;
+import net.sf.jsqlparser.util.deparser.StatementDeParser;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+import org.junit.jupiter.api.Test;
+
+/** Renderers separate words with exactly one space and add no trailing space. */
+class DeparseWhitespaceTest {
+
+    @ParameterizedTest
+    @ValueSource(strings = {"ALTER TABLE t DROP PRIMARY KEY",
+            "ALTER TABLE t DROP PRIMARY KEY CASCADE",
+            "ALTER TABLE t DROP PRIMARY KEY, DROP COLUMN c",
+            "RENAME TABLE t TO t2",
+            "RENAME TABLE a TO b, c TO d",
+            "RENAME TABLE IF EXISTS a TO b",
+            "RENAME a TO b",
+            "ALTER TABLE t ADD INDEX i (body (10))",
+            "ALTER TABLE t ADD KEY k (a, b)",
+            "CREATE TABLE t (a INT, INDEX i (a))"})
+    void rendersSingleSpaces(String sql) throws JSQLParserException {
+        Statement statement =
+                CCJSqlParserUtil.parse(sql, parser -> parser.withDialect(Dialect.MYSQL));
+        assertEquals(sql, statement.toString());
+
+        StringBuilder deparsed = new StringBuilder();
+        statement.accept(new StatementDeParser(deparsed));
+        assertEquals(sql, deparsed.toString());
+    }
+
+    @Test
+    void indexDeclarationHasNoLeadingSpace() {
+        assertEquals("i2", new Index().withName("i2").toString());
+        assertEquals("KEY k (a)", new Index().withIndexKeyword("KEY").withName("k")
+                .withColumnsNames(java.util.List.of("a")).toString());
+        assertEquals("UNIQUE INDEX u (a)", new Index().withType("UNIQUE").withIndexKeyword("INDEX")
+                .withName("u").withColumnsNames(java.util.List.of("a")).toString());
+    }
+}

src/test/java/net/sf/jsqlparser/statement/alter/IndexOptionBoundaryTest.java

@@ -47,7 +47,7 @@ void tablespaceBelongsToConstraintOptions(String key) throws JSQLParserException
     void mysqlAddIndexAttributes(String options) throws JSQLParserException {
         Alter alter = (Alter) parse("ALTER TABLE t ADD INDEX ix (id) " + options, Dialect.MYSQL);
         assertEquals("ix", alter.getAlterExpressions().get(0).getIndex().getName());
-        assertEquals("ALTER TABLE t ADD  INDEX ix (id) " + options, alter.toString());
+        assertEquals("ALTER TABLE t ADD INDEX ix (id) " + options, alter.toString());
         assertRoundTrip(alter, Dialect.MYSQL);
     }
 

src/test/java/net/sf/jsqlparser/util/deparser/TableConstraintExpressionDeParserTest.java

@@ -48,7 +48,7 @@ void createAndAlterFunctionalIndexesUseExpressionVisitor() throws JSQLParserExce
         assertRewrite("CREATE TABLE t (id INT, INDEX idx ((id + 1)))",
                 "CREATE TABLE t (id INT, INDEX idx ((mapped_id + 101)))");
         assertRewrite("ALTER TABLE t ADD INDEX idx ((id + 1))",
-                "ALTER TABLE t ADD  INDEX idx ((mapped_id + 101))");
+                "ALTER TABLE t ADD INDEX idx ((mapped_id + 101))");
     }
 
     @ParameterizedTest