feat: support MySQL ALTER DATABASE options

src/main/java/net/sf/jsqlparser/statement/StatementVisitor.java

@@ -9,6 +9,7 @@
  */
 package net.sf.jsqlparser.statement;
 
+import net.sf.jsqlparser.statement.alter.database.AlterDatabase;
 import net.sf.jsqlparser.statement.alter.schema.AlterSchema;
 import net.sf.jsqlparser.statement.oracle.OracleBlock;
 import net.sf.jsqlparser.statement.oracle.OracleAssignment;
@@ -671,4 +672,12 @@ default void visit(OracleNullStatement statement) {
         visit(statement, null);
     }
 
+    default <S> T visit(AlterDatabase statement, S context) {
+        return null;
+    }
+
+    default void visit(AlterDatabase statement) {
+        visit(statement, null);
+    }
+
 }

src/main/java/net/sf/jsqlparser/statement/alter/database/AlterDatabase.java

@@ -0,0 +1,67 @@
+/*-
+ * #%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.database;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import net.sf.jsqlparser.statement.Statement;
+import net.sf.jsqlparser.statement.StatementVisitor;
+import net.sf.jsqlparser.statement.create.database.DatabaseOption;
+
+/** MySQL ALTER DATABASE (or SCHEMA); a missing name selects the current database. */
+public class AlterDatabase implements Statement {
+    private String databaseName;
+    private boolean useSchemaKeyword;
+    private final List<DatabaseOption> options = new ArrayList<>();
+
+    public String getDatabaseName() {
+        return databaseName;
+    }
+
+    public void setDatabaseName(String databaseName) {
+        this.databaseName = databaseName;
+    }
+
+    public boolean isUseSchemaKeyword() {
+        return useSchemaKeyword;
+    }
+
+    public void setUseSchemaKeyword(boolean useSchemaKeyword) {
+        this.useSchemaKeyword = useSchemaKeyword;
+    }
+
+    public List<DatabaseOption> getOptions() {
+        return options;
+    }
+
+    public Optional<DatabaseOption> getOption(DatabaseOption.Kind kind) {
+        return options.stream().filter(option -> option.getKind() == kind).findFirst();
+    }
+
+    public StringBuilder appendTo(StringBuilder builder) {
+        builder.append(useSchemaKeyword ? "ALTER SCHEMA" : "ALTER DATABASE");
+        if (databaseName != null) {
+            builder.append(' ').append(databaseName);
+        }
+        options.forEach(option -> builder.append(' ').append(option));
+        return builder;
+    }
+
+    @Override
+    public String toString() {
+        return appendTo(new StringBuilder()).toString();
+    }
+
+    @Override
+    public <T, S> T accept(StatementVisitor<T> visitor, S context) {
+        return visitor.visit(this, context);
+    }
+}

src/main/java/net/sf/jsqlparser/statement/create/database/DatabaseOption.java

@@ -14,11 +14,14 @@
 import java.util.Collections;
 import java.util.List;
 
-/** A structured option shared by MySQL {@code CREATE DATABASE} and {@code CREATE SCHEMA}. */
+/**
+ * A structured option shared by MySQL {@code CREATE/ALTER DATABASE} and
+ * {@code CREATE/ALTER SCHEMA}.
+ */
 public class DatabaseOption implements Serializable {
 
     public enum Kind {
-        CHARACTER_SET, COLLATE, ENCRYPTION, OTHER
+        CHARACTER_SET, COLLATE, ENCRYPTION, READ_ONLY, OTHER
     }
 
     private Kind kind = Kind.OTHER;

src/main/java/net/sf/jsqlparser/util/TablesNamesFinder.java

@@ -9,6 +9,7 @@
  */
 package net.sf.jsqlparser.util;
 
+import net.sf.jsqlparser.statement.alter.database.AlterDatabase;
 import net.sf.jsqlparser.statement.alter.schema.AlterSchema;
 import net.sf.jsqlparser.statement.select.MatchRecognize;
 import net.sf.jsqlparser.expression.RowPatternFunction;
@@ -2912,4 +2913,9 @@ public <S> Void visit(OracleNullStatement statement, S context) {
         return null;
     }
 
+    @Override
+    public <S> Void visit(AlterDatabase statement, S context) {
+        return null;
+    }
+
 }

src/main/java/net/sf/jsqlparser/util/deparser/StatementDeParser.java

@@ -9,6 +9,7 @@
  */
 package net.sf.jsqlparser.util.deparser;
 
+import net.sf.jsqlparser.statement.alter.database.AlterDatabase;
 import net.sf.jsqlparser.statement.alter.schema.AlterSchema;
 import net.sf.jsqlparser.statement.oracle.OracleBlock;
 import net.sf.jsqlparser.statement.oracle.OracleAssignment;
@@ -809,4 +810,9 @@ public <S> StringBuilder visit(OracleNullStatement statement, S context) {
         return builder.append("NULL");
     }
 
+    @Override
+    public <S> StringBuilder visit(AlterDatabase statement, S context) {
+        return statement.appendTo(builder);
+    }
+
 }

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

@@ -50,6 +50,7 @@ import net.sf.jsqlparser.statement.*;
 import net.sf.jsqlparser.statement.analyze.*;
 import net.sf.jsqlparser.statement.alter.*;
 import net.sf.jsqlparser.statement.alter.schema.AlterSchema;
+import net.sf.jsqlparser.statement.alter.database.AlterDatabase;
 import net.sf.jsqlparser.statement.alter.sequence.*;
 import net.sf.jsqlparser.statement.comment.*;
 import net.sf.jsqlparser.statement.create.database.*;
@@ -14652,6 +14653,35 @@ DatabaseOption MySqlDatabaseOption():
     { return new DatabaseOption(kind, name, value, useDefault, useEquals); }
 }
 
+/** Reuses CREATE's database options; READ ONLY is specific to ALTER. */
+AlterDatabase AlterDatabase():
+{
+    AlterDatabase result = new AlterDatabase();
+    String name;
+    DatabaseOption option;
+    Token value;
+    boolean equals;
+}
+{
+    ( <K_DATABASE> | <K_SCHEMA> { result.setUseSchemaKeyword(true); } )
+    [ LOOKAHEAD({ !isMySqlDatabaseOptionAhead() && getToken(1).kind != K_READ })
+        name=RelObjectName() { result.setDatabaseName(name); } ]
+    (
+        (
+            LOOKAHEAD({ isMySqlDatabaseOptionAhead() }) option=MySqlDatabaseOption()
+            |
+            <K_READ> <K_ONLY> { equals = false; }
+            [ "=" { equals = true; } ]
+            ( value=<K_DEFAULT> | value=<S_LONG> ) {
+                requireDdlSyntax(value.kind == K_DEFAULT || "0".equals(value.image) || "1".equals(value.image),
+                        "READ ONLY requires DEFAULT, 0, or 1");
+                option = new DatabaseOption(DatabaseOption.Kind.READ_ONLY, "READ ONLY", value.image, false, equals);
+            }
+        ) { result.getOptions().add(option); }
+    )+
+    { return result; }
+}
+
 List<String> PathSpecification():
 {
     Token tk;
@@ -17951,6 +17981,10 @@ Statement Alter():
                 |
                 statement = AlterDefaultPrivileges()
                 |
+                LOOKAHEAD({ getToken(1).kind == K_DATABASE || (getToken(1).kind == K_SCHEMA
+                        && Dialect.MYSQL.name().equals(getAsString(Feature.dialect))) })
+                statement = AlterDatabase()
+                |
                 LOOKAHEAD(<K_SCHEMA>) statement = AlterSchema()
                 |
                 LOOKAHEAD(<K_TYPE>) statement = AlterType()

src/test/java/net/sf/jsqlparser/statement/alter/database/AlterDatabaseTest.java

@@ -0,0 +1,69 @@
+/*-
+ * #%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.database;
+
+import static org.junit.jupiter.api.Assertions.*;
+import net.sf.jsqlparser.JSQLParserException;
+import net.sf.jsqlparser.parser.AbstractJSqlParser.Dialect;
+import net.sf.jsqlparser.parser.CCJSqlParserUtil;
+import net.sf.jsqlparser.statement.StatementVisitorAdapter;
+import net.sf.jsqlparser.statement.create.database.DatabaseOption;
+import net.sf.jsqlparser.util.TablesNamesFinder;
+import net.sf.jsqlparser.util.deparser.StatementDeParser;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+class AlterDatabaseTest {
+    @ParameterizedTest
+    @ValueSource(strings = {
+            "ALTER DATABASE d CHARACTER SET utf8mb4 COLLATE utf8mb4_bin",
+            "ALTER SCHEMA `d` DEFAULT CHARACTER SET = utf8mb4 DEFAULT COLLATE = utf8mb4_bin",
+            "ALTER DATABASE d DEFAULT ENCRYPTION = 'N'",
+            "ALTER DATABASE d READ ONLY = 0", "ALTER DATABASE d READ ONLY 1",
+            "ALTER DATABASE READ ONLY = DEFAULT", "ALTER SCHEMA DEFAULT CHARACTER SET utf8mb4"})
+    void roundTripAndStatementBoundary(String sql) throws JSQLParserException {
+        AlterDatabase statement = parse(sql);
+        assertEquals(sql, statement.toString());
+        StringBuilder buffer = new StringBuilder();
+        statement.accept(new StatementDeParser(buffer), null);
+        assertEquals(sql, buffer.toString());
+        assertEquals(sql, parse(buffer.toString()).toString());
+        assertTrue(new TablesNamesFinder().getTables(statement).isEmpty());
+        assertEquals(2, CCJSqlParserUtil.parseStatements(sql + "; SELECT 1",
+                p -> p.withDialect(Dialect.MYSQL)).size());
+    }
+
+    @Test
+    void optionMutationAndVisitorDispatch() throws JSQLParserException {
+        AlterDatabase statement = parse("ALTER DATABASE old_db READ ONLY = 0");
+        statement.setDatabaseName("new_db");
+        statement.getOption(DatabaseOption.Kind.READ_ONLY).orElseThrow().setValue("1");
+        assertEquals("ALTER DATABASE new_db READ ONLY = 1", statement.toString());
+        assertEquals("context:new_db", statement.accept(new StatementVisitorAdapter<String>() {
+            @Override
+            public <S> String visit(AlterDatabase database, S context) {
+                return context + ":" + database.getDatabaseName();
+            }
+        }, "context"));
+    }
+
+    @Test
+    void rejectIncompleteAndInvalidReadOnly() {
+        for (String sql : new String[] {"ALTER DATABASE d", "ALTER DATABASE d READ ONLY = 2",
+                "ALTER DATABASE d DEFAULT READ ONLY = 0"}) {
+            assertThrows(JSQLParserException.class, () -> parse(sql));
+        }
+    }
+
+    private static AlterDatabase parse(String sql) throws JSQLParserException {
+        return (AlterDatabase) CCJSqlParserUtil.parse(sql, p -> p.withDialect(Dialect.MYSQL));
+    }
+}