Support PREPARE and DEALLOCATE statements

Adds PREPARE name AS statement and DEALLOCATE [PREPARE] name. EXECUTE of
a prepared statement already parsed. The prepared statement is a nested
Statement, so TablesNamesFinder reaches its tables.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EqinwHBKuAtPEmtXr3b5P2

Author: hayssams

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

@@ -0,0 +1,70 @@
+/*-
+ * #%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;
+
+/**
+ * {@code DEALLOCATE [PREPARE] name}, which drops a statement prepared by
+ * {@link PrepareStatement}.
+ */
+public class DeallocateStatement implements Statement {
+    private String name;
+    private boolean usingPrepareKeyword;
+
+    public DeallocateStatement() {}
+
+    public DeallocateStatement(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public DeallocateStatement withName(String name) {
+        setName(name);
+        return this;
+    }
+
+    public boolean isUsingPrepareKeyword() {
+        return usingPrepareKeyword;
+    }
+
+    public void setUsingPrepareKeyword(boolean usingPrepareKeyword) {
+        this.usingPrepareKeyword = usingPrepareKeyword;
+    }
+
+    public DeallocateStatement withUsingPrepareKeyword(boolean usingPrepareKeyword) {
+        setUsingPrepareKeyword(usingPrepareKeyword);
+        return this;
+    }
+
+    public StringBuilder appendTo(StringBuilder builder) {
+        builder.append("DEALLOCATE ");
+        if (usingPrepareKeyword) {
+            builder.append("PREPARE ");
+        }
+        builder.append(name);
+        return builder;
+    }
+
+    @Override
+    public String toString() {
+        return appendTo(new StringBuilder()).toString();
+    }
+
+    @Override
+    public <T, S> T accept(StatementVisitor<T> statementVisitor, S context) {
+        return statementVisitor.visit(this, context);
+    }
+}

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

@@ -0,0 +1,70 @@
+/*-
+ * #%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;
+
+/**
+ * {@code PREPARE name AS statement}, which stores a parameterised statement for later
+ * {@code EXECUTE}.
+ *
+ * @see <a href="https://duckdb.org/docs/stable/sql/query_syntax/prepared_statements">Prepared
+ *      statements</a>
+ */
+public class PrepareStatement implements Statement {
+    private String name;
+    private Statement statement;
+
+    public PrepareStatement() {}
+
+    public PrepareStatement(String name, Statement statement) {
+        this.name = name;
+        this.statement = statement;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public PrepareStatement withName(String name) {
+        setName(name);
+        return this;
+    }
+
+    public Statement getStatement() {
+        return statement;
+    }
+
+    public void setStatement(Statement statement) {
+        this.statement = statement;
+    }
+
+    public PrepareStatement withStatement(Statement statement) {
+        setStatement(statement);
+        return this;
+    }
+
+    public StringBuilder appendTo(StringBuilder builder) {
+        builder.append("PREPARE ").append(name).append(" AS ").append(statement);
+        return builder;
+    }
+
+    @Override
+    public String toString() {
+        return appendTo(new StringBuilder()).toString();
+    }
+
+    @Override
+    public <T, S> T accept(StatementVisitor<T> statementVisitor, S context) {
+        return statementVisitor.visit(this, context);
+    }
+}

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

@@ -563,6 +563,20 @@ public <S> Void visit(DisconnectStatement disconnectStatement, S context) {
         return null;
     }
 
+    @Override
+    public <S> Void visit(PrepareStatement prepareStatement, S context) {
+        analysis.claimTopLevel();
+        analysis.certain(StmtFeature.MODIFIES_SESSION);
+        return null;
+    }
+
+    @Override
+    public <S> Void visit(DeallocateStatement deallocateStatement, S context) {
+        analysis.claimTopLevel();
+        analysis.certain(StmtFeature.MODIFIES_SESSION);
+        return null;
+    }
+
     @Override
     public <S> Void visit(PurgeStatement purgeStatement, S context) {
         analysis.claimTopLevel();

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

@@ -407,6 +407,18 @@ default void visit(DisconnectStatement disconnectStatement) {
         this.visit(disconnectStatement, null);
     }
 
+    <S> T visit(PrepareStatement prepareStatement, S context);
+
+    default void visit(PrepareStatement prepareStatement) {
+        this.visit(prepareStatement, null);
+    }
+
+    <S> T visit(DeallocateStatement deallocateStatement, S context);
+
+    default void visit(DeallocateStatement deallocateStatement) {
+        this.visit(deallocateStatement, null);
+    }
+
     <S> T visit(PurgeStatement purgeStatement, S context);
 
     default void visit(PurgeStatement purgeStatement) {

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

@@ -648,6 +648,16 @@ public <S> T visit(DisconnectStatement disconnectStatement, S context) {
         return null;
     }
 
+    @Override
+    public <S> T visit(PrepareStatement prepareStatement, S context) {
+        return null;
+    }
+
+    @Override
+    public <S> T visit(DeallocateStatement deallocateStatement, S context) {
+        return null;
+    }
+
     @Override
     public <S> T visit(PurgeStatement purgeStatement, S context) {
         return null;

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

@@ -215,6 +215,8 @@
 import net.sf.jsqlparser.statement.DetachStatement;
 import net.sf.jsqlparser.statement.ConnectStatement;
 import net.sf.jsqlparser.statement.DisconnectStatement;
+import net.sf.jsqlparser.statement.PrepareStatement;
+import net.sf.jsqlparser.statement.DeallocateStatement;
 
 
 /**
@@ -2540,6 +2542,28 @@ public void visit(DisconnectStatement disconnectStatement) {
         StatementVisitor.super.visit(disconnectStatement);
     }
 
+    @Override
+    public <S> Void visit(PrepareStatement prepareStatement, S context) {
+        prepareStatement.getStatement().accept(this, context);
+        return null;
+    }
+
+    @Override
+    public void visit(PrepareStatement prepareStatement) {
+        StatementVisitor.super.visit(prepareStatement);
+    }
+
+    @Override
+    public <S> Void visit(DeallocateStatement deallocateStatement, S context) {
+        // no tables involved in this statement
+        return null;
+    }
+
+    @Override
+    public void visit(DeallocateStatement deallocateStatement) {
+        StatementVisitor.super.visit(deallocateStatement);
+    }
+
     @Override
     public <S> Void visit(PurgeStatement purgeStatement, S context) {
         if (purgeStatement.getPurgeObjectType() == PurgeObjectType.TABLE) {

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

@@ -103,6 +103,8 @@
 import net.sf.jsqlparser.statement.DetachStatement;
 import net.sf.jsqlparser.statement.ConnectStatement;
 import net.sf.jsqlparser.statement.DisconnectStatement;
+import net.sf.jsqlparser.statement.PrepareStatement;
+import net.sf.jsqlparser.statement.DeallocateStatement;
 
 public class StatementDeParser extends AbstractDeParser<Statement>
         implements StatementVisitor<StringBuilder> {
@@ -598,6 +600,18 @@ public <S> StringBuilder visit(DisconnectStatement disconnectStatement, S contex
         return builder;
     }
 
+    @Override
+    public <S> StringBuilder visit(PrepareStatement prepareStatement, S context) {
+        prepareStatement.appendTo(builder);
+        return builder;
+    }
+
+    @Override
+    public <S> StringBuilder visit(DeallocateStatement deallocateStatement, S context) {
+        deallocateStatement.appendTo(builder);
+        return builder;
+    }
+
     @Override
     public <S> StringBuilder visit(PurgeStatement purgeStatement, S context) {
         purgeStatement.appendTo(builder);

src/main/java/net/sf/jsqlparser/util/validation/validator/StatementValidator.java

@@ -105,6 +105,8 @@
 import net.sf.jsqlparser.statement.DetachStatement;
 import net.sf.jsqlparser.statement.ConnectStatement;
 import net.sf.jsqlparser.statement.DisconnectStatement;
+import net.sf.jsqlparser.statement.PrepareStatement;
+import net.sf.jsqlparser.statement.DeallocateStatement;
 
 /**
  * @author gitmotte
@@ -519,6 +521,18 @@ public <S> Void visit(DisconnectStatement disconnectStatement, S context) {
         return null;
     }
 
+    @Override
+    public <S> Void visit(PrepareStatement prepareStatement, S context) {
+        // TODO: not yet implemented
+        return null;
+    }
+
+    @Override
+    public <S> Void visit(DeallocateStatement deallocateStatement, S context) {
+        // TODO: not yet implemented
+        return null;
+    }
+
     @Override
     public <S> Void visit(PurgeStatement purgeStatement, S context) {
         // TODO: not yet implemented
@@ -759,6 +773,14 @@ public void visit(DisconnectStatement disconnectStatement) {
         visit(disconnectStatement, null);
     }
 
+    public void visit(PrepareStatement prepareStatement) {
+        visit(prepareStatement, null);
+    }
+
+    public void visit(DeallocateStatement deallocateStatement) {
+        visit(deallocateStatement, null);
+    }
+
     public void visit(PurgeStatement purgeStatement) {
         visit(purgeStatement, null);
     }

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

@@ -2020,6 +2020,7 @@ String NonReservedWord() :
       | tk=<K_DBA_RECYCLEBIN: "DBA_RECYCLEBIN">
       | tk=<K_DEFAULTS: "DEFAULTS">
       | tk=<K_DEPTH: "DEPTH">
+      | tk=<K_DEALLOCATE: "DEALLOCATE">
       | tk=<K_DEFERRABLE : "DEFERRABLE">
       | tk=<K_DELAYED : "DELAYED">
       | tk=<K_DELETE:"DELETE">
@@ -2204,6 +2205,7 @@ String NonReservedWord() :
       | tk=<K_PLAN:"PLAN">
       | tk=<K_PLUS:"PLUS">
       | tk=<K_PRAGMA: "PRAGMA">
+      | tk=<K_PREPARE: "PREPARE">
       | tk=<K_PRECEDING: "PRECEDING">
       | tk=<K_PRIMARY:"PRIMARY">
       | tk=<K_POLICY:"POLICY">
@@ -2958,6 +2960,10 @@ Statement SingleStatement() :
             LOOKAHEAD({ getToken(1).kind == K_DISCONNECT && getToken(2).kind != K_SESSION })
             stm = DisconnectStatement()
             |
+            LOOKAHEAD({ getToken(1).kind == K_PREPARE }) stm = PrepareStatement()
+            |
+            LOOKAHEAD({ getToken(1).kind == K_DEALLOCATE }) stm = DeallocateStatement()
+            |
             stm = PurgeStatement()
             |
             stm = SessionStatement()
@@ -4359,6 +4365,37 @@ RenameTableStatement RenameTableStatement(): {
     }
 }
 
+/**
+ * PREPARE name AS statement, storing a parameterised statement for later EXECUTE.
+ */
+PrepareStatement PrepareStatement() #PrepareStatement:
+{
+    PrepareStatement prepareStatement = new PrepareStatement();
+    ObjectNames name;
+    Statement statement;
+}
+{
+    <K_PREPARE> name=RelObjectNames()
+    { prepareStatement.setName(String.join(".", name.getNames())); }
+    <K_AS> statement=SingleStatement() { prepareStatement.setStatement(statement); }
+    { return prepareStatement; }
+}
+
+/**
+ * DEALLOCATE [PREPARE] name.
+ */
+DeallocateStatement DeallocateStatement() #DeallocateStatement:
+{
+    DeallocateStatement deallocateStatement = new DeallocateStatement();
+    ObjectNames name;
+}
+{
+    <K_DEALLOCATE>
+    [ LOOKAHEAD(2) <K_PREPARE> { deallocateStatement.setUsingPrepareKeyword(true); } ]
+    name=RelObjectNames() { deallocateStatement.setName(String.join(".", name.getNames())); }
+    { return deallocateStatement; }
+}
+
 /**
  * DuckDB's CONNECT target [AS alias], routing the session to a remote database.
  */