Parse PostgreSQL ALTER DATABASE and share typed database options

src/main/java/net/sf/jsqlparser/parser/feature/Feature.java

@@ -509,6 +509,12 @@ public enum Feature {
      * @see CreateDatabase
      */
     createDatabase,
+    /**
+     * SQL "ALTER DATABASE" statement is allowed
+     *
+     * @see net.sf.jsqlparser.statement.alter.database.AlterDatabase
+     */
+    alterDatabase,
     /**
      * SQL "CREATE SCHEMA" statement is allowed
      *

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

@@ -0,0 +1,174 @@
+/*-
+ * #%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;
+
+import java.io.Serializable;
+import java.util.function.Consumer;
+import net.sf.jsqlparser.expression.Expression;
+import net.sf.jsqlparser.expression.operators.relational.ExpressionList;
+
+/**
+ * A PostgreSQL {@code SET} or {@code RESET} of a configuration parameter, shared by statements that
+ * store parameter defaults, such as {@code ALTER ROLE} and {@code ALTER DATABASE}:
+ *
+ * <pre>
+ * SET parameter { TO | = } { value [, ...] | DEFAULT }
+ * SET parameter FROM CURRENT
+ * RESET { parameter | ALL }
+ * </pre>
+ *
+ * Parameter names keep their SQL spelling, including qualifiers and identifier quotes.
+ * {@code RESET ALL} uses the parameter name {@code ALL}.
+ */
+public class ConfigurationParameterChange implements Serializable {
+
+    public enum Action {
+        SET, RESET
+    }
+
+    /** What a {@code SET} assigns. Only the selected kind is rendered. */
+    public enum ValueKind {
+        /** The explicit values of {@link #getValues()}. */
+        VALUES,
+        /** {@code TO DEFAULT} or {@code = DEFAULT}. */
+        DEFAULT,
+        /** {@code FROM CURRENT}. */
+        FROM_CURRENT
+    }
+
+    private Action action = Action.SET;
+    private String parameter;
+    private ValueKind valueKind = ValueKind.VALUES;
+    private boolean useEquals;
+    private ExpressionList<Expression> values;
+
+    public ConfigurationParameterChange() {}
+
+    public ConfigurationParameterChange(Action action, String parameter) {
+        this.action = action;
+        this.parameter = parameter;
+    }
+
+    public Action getAction() {
+        return action;
+    }
+
+    public void setAction(Action action) {
+        this.action = action;
+    }
+
+    public String getParameter() {
+        return parameter;
+    }
+
+    public void setParameter(String parameter) {
+        this.parameter = parameter;
+    }
+
+    public ValueKind getValueKind() {
+        return valueKind;
+    }
+
+    /**
+     * Selects what a {@code SET} assigns. The values are retained when another kind is selected.
+     *
+     * @param valueKind the assigned value kind
+     */
+    public void setValueKind(ValueKind valueKind) {
+        this.valueKind = valueKind;
+    }
+
+    /**
+     * Whether {@code =} rather than {@code TO} precedes the value.
+     *
+     * @return {@code true} for {@code =}
+     */
+    public boolean isUseEquals() {
+        return useEquals;
+    }
+
+    public void setUseEquals(boolean useEquals) {
+        this.useEquals = useEquals;
+    }
+
+    /**
+     * The values assigned by {@link ValueKind#VALUES}, as a mutable list.
+     *
+     * @return the values, or {@code null} if none were set
+     */
+    public ExpressionList<Expression> getValues() {
+        return values;
+    }
+
+    public void setValues(ExpressionList<Expression> values) {
+        this.values = values;
+    }
+
+    public ConfigurationParameterChange withAction(Action action) {
+        setAction(action);
+        return this;
+    }
+
+    public ConfigurationParameterChange withParameter(String parameter) {
+        setParameter(parameter);
+        return this;
+    }
+
+    public ConfigurationParameterChange withValueKind(ValueKind valueKind) {
+        setValueKind(valueKind);
+        return this;
+    }
+
+    public ConfigurationParameterChange withUseEquals(boolean useEquals) {
+        setUseEquals(useEquals);
+        return this;
+    }
+
+    public ConfigurationParameterChange withValues(ExpressionList<Expression> values) {
+        setValues(values);
+        return this;
+    }
+
+    /**
+     * Appends this clause to a builder.
+     *
+     * @param builder the target
+     * @param valueRenderer appends each value, for example through an expression deparser
+     * @return the builder
+     */
+    public StringBuilder appendTo(StringBuilder builder, Consumer<Expression> valueRenderer) {
+        if (action == Action.RESET) {
+            return builder.append("RESET ").append(parameter);
+        }
+        builder.append("SET ").append(parameter);
+        if (valueKind == ValueKind.FROM_CURRENT) {
+            return builder.append(" FROM CURRENT");
+        }
+        builder.append(useEquals ? " = " : " TO ");
+        if (valueKind == ValueKind.DEFAULT) {
+            return builder.append("DEFAULT");
+        }
+        if (values != null) {
+            for (int i = 0; i < values.size(); i++) {
+                if (i > 0) {
+                    builder.append(", ");
+                }
+                valueRenderer.accept(values.get(i));
+            }
+        }
+        return builder;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder builder = new StringBuilder();
+        return appendTo(builder, builder::append).toString();
+    }
+}

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

@@ -12,15 +12,44 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
+import java.util.function.Consumer;
+import net.sf.jsqlparser.expression.Expression;
+import net.sf.jsqlparser.statement.ConfigurationParameterChange;
 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. */
+/**
+ * MySQL or PostgreSQL {@code ALTER DATABASE}. MySQL's {@code ALTER SCHEMA} synonym only changes
+ * options, and a missing name selects the current database. The options use the same
+ * {@link DatabaseOption} model as {@code CREATE DATABASE}. Names retain SQL identifier quoting.
+ */
 public class AlterDatabase implements Statement {
+
+    public enum Action {
+        /** MySQL options or PostgreSQL {@code [WITH] option ...}, see {@link #getOptions()}. */
+        OPTIONS,
+        /** {@code RENAME TO}, see {@link #getNewName()}. */
+        RENAME,
+        /** {@code OWNER TO}, see {@link #getOwner()}. */
+        OWNER,
+        /** {@code SET TABLESPACE}, see {@link #getTablespace()}. */
+        SET_TABLESPACE,
+        /** {@code REFRESH COLLATION VERSION}. */
+        REFRESH_COLLATION_VERSION,
+        /** {@code SET} or {@code RESET}, see {@link #getParameterChange()}. */
+        CONFIGURATION_PARAMETER
+    }
+
     private String databaseName;
     private boolean useSchemaKeyword;
+    private Action action = Action.OPTIONS;
+    private boolean useWith;
     private final List<DatabaseOption> options = new ArrayList<>();
+    private String newName;
+    private String owner;
+    private String tablespace;
+    private ConfigurationParameterChange parameterChange;
 
     public String getDatabaseName() {
         return databaseName;
@@ -38,6 +67,37 @@ public void setUseSchemaKeyword(boolean useSchemaKeyword) {
         this.useSchemaKeyword = useSchemaKeyword;
     }
 
+    /**
+     * The rendered alteration. Payloads of other actions are retained for a later switch back.
+     *
+     * @return the action, {@link Action#OPTIONS} unless changed
+     */
+    public Action getAction() {
+        return action;
+    }
+
+    public void setAction(Action action) {
+        this.action = action;
+    }
+
+    /**
+     * Whether PostgreSQL's optional {@code WITH} precedes the options.
+     *
+     * @return {@code true} if {@code WITH} is rendered
+     */
+    public boolean isUseWith() {
+        return useWith;
+    }
+
+    public void setUseWith(boolean useWith) {
+        this.useWith = useWith;
+    }
+
+    /**
+     * The options of {@link Action#OPTIONS}, as a mutable list.
+     *
+     * @return the options in source order
+     */
     public List<DatabaseOption> getOptions() {
         return options;
     }
@@ -46,13 +106,81 @@ public Optional<DatabaseOption> getOption(DatabaseOption.Kind kind) {
         return options.stream().filter(option -> option.getKind() == kind).findFirst();
     }
 
+    public String getNewName() {
+        return newName;
+    }
+
+    public void setNewName(String newName) {
+        this.newName = newName;
+    }
+
+    /**
+     * The new owner, a role name or {@code CURRENT_USER}, {@code CURRENT_ROLE} or
+     * {@code SESSION_USER}.
+     *
+     * @return the owner
+     */
+    public String getOwner() {
+        return owner;
+    }
+
+    public void setOwner(String owner) {
+        this.owner = owner;
+    }
+
+    public String getTablespace() {
+        return tablespace;
+    }
+
+    public void setTablespace(String tablespace) {
+        this.tablespace = tablespace;
+    }
+
+    public ConfigurationParameterChange getParameterChange() {
+        return parameterChange;
+    }
+
+    public void setParameterChange(ConfigurationParameterChange parameterChange) {
+        this.parameterChange = parameterChange;
+    }
+
     public StringBuilder appendTo(StringBuilder builder) {
+        return appendTo(builder, builder::append);
+    }
+
+    /**
+     * Appends this statement to a builder.
+     *
+     * @param builder the target
+     * @param valueRenderer appends each configuration parameter value
+     * @return the builder
+     */
+    public StringBuilder appendTo(StringBuilder builder, Consumer<Expression> valueRenderer) {
         builder.append(useSchemaKeyword ? "ALTER SCHEMA" : "ALTER DATABASE");
         if (databaseName != null) {
             builder.append(' ').append(databaseName);
         }
-        options.forEach(option -> builder.append(' ').append(option));
-        return builder;
+        switch (action) {
+            case RENAME:
+                return builder.append(" RENAME TO ").append(newName);
+            case OWNER:
+                return builder.append(" OWNER TO ").append(owner);
+            case SET_TABLESPACE:
+                return builder.append(" SET TABLESPACE ").append(tablespace);
+            case REFRESH_COLLATION_VERSION:
+                return builder.append(" REFRESH COLLATION VERSION");
+            case CONFIGURATION_PARAMETER:
+                if (parameterChange == null) {
+                    throw new IllegalStateException("Expected a configuration parameter change");
+                }
+                return parameterChange.appendTo(builder.append(' '), valueRenderer);
+            default:
+                if (useWith) {
+                    builder.append(" WITH");
+                }
+                options.forEach(option -> builder.append(' ').append(option));
+                return builder;
+        }
     }
 
     @Override