From 67ded76153d41619ba09523697020d12a5b25a64 Mon Sep 17 00:00:00 2001
From: Jerome Haltom <jhaltom@alethic.solutions>
Date: Mon, 7 Sep 2026 19:26:51 -0500
Subject: [PATCH] [CALCITE-7768] SqlDialect has no way to unparse a UUID
 literal

---
 .../src/main/java/org/apache/calcite/sql/SqlDialect.java | 9 +++++++++
 .../main/java/org/apache/calcite/sql/SqlUuidLiteral.java | 2 +-
 .../org/apache/calcite/sql/dialect/MssqlSqlDialect.java  | 6 ++++++
 .../calcite/rel/rel2sql/RelToSqlConverterTest.java       | 9 +++++++++
 4 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/core/src/main/java/org/apache/calcite/sql/SqlDialect.java b/core/src/main/java/org/apache/calcite/sql/SqlDialect.java
index eef1c386d594..48a566a84a5b 100644
--- a/core/src/main/java/org/apache/calcite/sql/SqlDialect.java
+++ b/core/src/main/java/org/apache/calcite/sql/SqlDialect.java
@@ -579,6 +579,15 @@ public void unparseTableScanHints(SqlWriter writer,
       SqlNodeList hints, int leftPrec, int rightPrec) {
   }
 
+  /** Converts a UUID literal to a SQL string. The default implementation
+   * returns strings such as
+   * <code>UUID '123e4567-e89b-12d3-a456-426655440000'</code>. A dialect whose
+   * product spells it differently should override this method. */
+  public void unparseUuidLiteral(SqlWriter writer,
+      SqlUuidLiteral literal, int leftPrec, int rightPrec) {
+    writer.literal(literal.toString());
+  }
+
   /**
    * Returns whether the string contains any characters outside the
    * comfortable 7-bit ASCII range (32 through 127, plus linefeed (10) and
diff --git a/core/src/main/java/org/apache/calcite/sql/SqlUuidLiteral.java b/core/src/main/java/org/apache/calcite/sql/SqlUuidLiteral.java
index 9a1d165a1f8a..65f089a5d486 100644
--- a/core/src/main/java/org/apache/calcite/sql/SqlUuidLiteral.java
+++ b/core/src/main/java/org/apache/calcite/sql/SqlUuidLiteral.java
@@ -58,6 +58,6 @@ public String toFormattedString() {
       SqlWriter writer,
       int leftPrec,
       int rightPrec) {
-    writer.literal(this.toString());
+    writer.getDialect().unparseUuidLiteral(writer, this, leftPrec, rightPrec);
   }
 }
diff --git a/core/src/main/java/org/apache/calcite/sql/dialect/MssqlSqlDialect.java b/core/src/main/java/org/apache/calcite/sql/dialect/MssqlSqlDialect.java
index 964fa03f8f91..184ea90d1615 100644
--- a/core/src/main/java/org/apache/calcite/sql/dialect/MssqlSqlDialect.java
+++ b/core/src/main/java/org/apache/calcite/sql/dialect/MssqlSqlDialect.java
@@ -38,6 +38,7 @@
 import org.apache.calcite.sql.SqlOperator;
 import org.apache.calcite.sql.SqlSyntax;
 import org.apache.calcite.sql.SqlUtil;
+import org.apache.calcite.sql.SqlUuidLiteral;
 import org.apache.calcite.sql.SqlWriter;
 import org.apache.calcite.sql.fun.SqlLibraryOperators;
 import org.apache.calcite.sql.fun.SqlStdOperatorTable;
@@ -200,6 +201,11 @@ private static SqlNode createDatetimeCastSpec(String typeAlias, RelDataType type
     writer.literal("'" + literal.toFormattedString() + "'");
   }
 
+  @Override public void unparseUuidLiteral(SqlWriter writer,
+      SqlUuidLiteral literal, int leftPrec, int rightPrec) {
+    writer.literal("'" + literal.toFormattedString() + "'");
+  }
+
   @Override public void unparseCall(SqlWriter writer, SqlCall call,
       int leftPrec, int rightPrec) {
     if (call.getOperator() == SqlStdOperatorTable.SUBSTRING) {
diff --git a/core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java b/core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java
index b09f299f8493..9af0ce098e9b 100644
--- a/core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java
+++ b/core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java
@@ -10988,6 +10988,15 @@ private void checkLiteral2(String expression, String expected) {
     sql(sql).ok(expected);
   }
 
+  /** Test case for <a href="https://issues.apache.org/jira/browse/CALCITE-7768">[CALCITE-7768]
+   * SqlDialect has no way to unparse a UUID literal</a>. */
+  @Test void testUuidMssql() {
+    final String sql = "SELECT UUID '123e4567-e89b-12d3-a456-426655440000' AS x";
+    final String expected = "SELECT *\n"
+        + "FROM (VALUES ('123e4567-e89b-12d3-a456-426655440000')) AS [t] ([X])";
+    sql(sql).withMssql().ok(expected);
+  }
+
   @Test void testUpdate() {
     final String sql0 = "update \"foodmart\".\"product\"\n"
         + "set \"product_name\" = 'calcite'";