Fix issue 2089: Add parsing functionality for MySQL CONVERT TO statement

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

@@ -57,6 +57,8 @@ public class AlterExpression implements Serializable {
 
     private List<ConstraintState> constraints;
     private List<String> parameters;
+    private String characterSet;
+    private String collation;
     private String lockOption;
     private String commentText;
 
@@ -396,6 +398,22 @@ public List<String> getParameters() {
         return parameters;
     }
 
+    public String getCharacterSet() {
+        return characterSet;
+    }
+
+    public void setCharacterSet(String characterSet) {
+        this.characterSet = characterSet;
+    }
+
+    public String getCollation() {
+        return collation;
+    }
+
+    public void setCollation(String collation) {
+        this.collation = collation;
+    }
+
     public String getLockOption() {
         return lockOption;
     }

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

@@ -10,7 +10,7 @@
 package net.sf.jsqlparser.statement.alter;
 
 public enum AlterOperation {
-    ADD, ALTER, DROP, DROP_PRIMARY_KEY, DROP_UNIQUE, DROP_FOREIGN_KEY, MODIFY, CHANGE, ALGORITHM, RENAME, RENAME_TABLE, RENAME_INDEX, RENAME_KEY, RENAME_CONSTRAINT, COMMENT, COMMENT_WITH_EQUAL_SIGN, UNSPECIFIC, TRUNCATE_PARTITION, LOCK;
+    ADD, ALTER, DROP, DROP_PRIMARY_KEY, DROP_UNIQUE, DROP_FOREIGN_KEY, MODIFY, CHANGE, CONVERT, ALGORITHM, RENAME, RENAME_TABLE, RENAME_INDEX, RENAME_KEY, RENAME_CONSTRAINT, COMMENT, COMMENT_WITH_EQUAL_SIGN, UNSPECIFIC, TRUNCATE_PARTITION, LOCK;
 
     public static AlterOperation from(String operation) {
         return Enum.valueOf(AlterOperation.class, operation.toUpperCase());

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -7322,6 +7322,11 @@ AlterExpression AlterExpression():
         (tk2=<S_IDENTIFIER> | tk2=<S_QUOTED_IDENTIFIER>) { alterExp.setNewTableName(tk2.image);}
       )
       |
+      (<K_CONVERT> { alterExp.setOperation(AlterOperation.CONVERT); }
+        <K_TO> <K_CHARACTER> <K_SET> tk=<S_IDENTIFIER> { alterExp.setCharacterSet(tk.image); }
+        [<K_COLLATE> tk2=<S_IDENTIFIER> { alterExp.setCollation(tk2.image); }]
+        )
+      |
       (<K_COMMENT> {alterExp.setOperation(AlterOperation.COMMENT);}
           ["=" {alterExp.setOperation(AlterOperation.COMMENT_WITH_EQUAL_SIGN);} ]
           tk=<S_CHAR_LITERAL> { alterExp.setCommentText(tk.image); }

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

@@ -1097,4 +1097,41 @@ public void testIssue2090LockExclusive() throws JSQLParserException {
         assertEquals(AlterOperation.LOCK, lockExp.getOperation());
         assertEquals("EXCLUSIVE", lockExp.getLockOption());
     }
+
+    @Test
+    public void testIssue2089() throws JSQLParserException {
+        String sql = "ALTER TABLE test_table CONVERT TO CHARACTER SET utf8mb4";
+        Statement stmt = CCJSqlParserUtil.parse(sql);
+        assertTrue(stmt instanceof Alter);
+        Alter alter = (Alter) stmt;
+        assertEquals("test_table", alter.getTable().getFullyQualifiedName());
+
+        List<AlterExpression> alterExpressions = alter.getAlterExpressions();
+        assertNotNull(alterExpressions);
+        assertEquals(1, alterExpressions.size());
+
+        AlterExpression convertExp = alterExpressions.get(0);
+        assertEquals(AlterOperation.CONVERT, convertExp.getOperation());
+        assertEquals("utf8mb4", convertExp.getCharacterSet());
+        assertNull(convertExp.getCollation());
+    }
+
+    @Test
+    public void testIssue2089WithCollation() throws JSQLParserException {
+        String sql =
+                "ALTER TABLE test_table CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci";
+        Statement stmt = CCJSqlParserUtil.parse(sql);
+        assertTrue(stmt instanceof Alter);
+        Alter alter = (Alter) stmt;
+        assertEquals("test_table", alter.getTable().getFullyQualifiedName());
+
+        List<AlterExpression> alterExpressions = alter.getAlterExpressions();
+        assertNotNull(alterExpressions);
+        assertEquals(1, alterExpressions.size());
+
+        AlterExpression convertExp = alterExpressions.get(0);
+        assertEquals(AlterOperation.CONVERT, convertExp.getOperation());
+        assertEquals("utf8mb4", convertExp.getCharacterSet());
+        assertEquals("utf8mb4_general_ci", convertExp.getCollation());
+    }
 }