[fix](prepare statement)Add placeholder literal for prepare stage.

fe/fe-core/src/main/java/org/apache/doris/nereids/rules/analysis/ExpressionAnalyzer.java

@@ -81,6 +81,7 @@
 import org.apache.doris.nereids.trees.expressions.literal.IntegerLikeLiteral;
 import org.apache.doris.nereids.trees.expressions.literal.Literal;
 import org.apache.doris.nereids.trees.expressions.literal.NullLiteral;
+import org.apache.doris.nereids.trees.expressions.literal.PlaceholderLiteral;
 import org.apache.doris.nereids.trees.expressions.literal.StringLiteral;
 import org.apache.doris.nereids.trees.expressions.typecoercion.ImplicitCastInputTypes;
 import org.apache.doris.nereids.trees.plans.PlaceholderId;
@@ -650,7 +651,7 @@ public Expression visitPlaceholder(Placeholder placeholder, ExpressionRewriteCon
         // In prepare stage, the realExpr has not been set, set it to StringLiteral so that we can plan the statement
         // and get the output slots in prepare stage, which is required by Mysql api definition.
         if (realExpr == null && context.cascadesContext.getStatementContext().isPrepareStage()) {
-            realExpr = new StringLiteral(String.valueOf(placeholder.getPlaceholderId().asInt()));
+            realExpr = new PlaceholderLiteral(String.valueOf(placeholder.getPlaceholderId().asInt()));
         }
         return visit(realExpr, context);
     }

fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/scalar/DateTrunc.java

@@ -24,6 +24,7 @@
 import org.apache.doris.nereids.trees.expressions.functions.Monotonic;
 import org.apache.doris.nereids.trees.expressions.functions.PropagateNullLiteral;
 import org.apache.doris.nereids.trees.expressions.functions.PropagateNullable;
+import org.apache.doris.nereids.trees.expressions.literal.PlaceholderLiteral;
 import org.apache.doris.nereids.trees.expressions.literal.StringLikeLiteral;
 import org.apache.doris.nereids.trees.expressions.shape.BinaryExpression;
 import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
@@ -65,16 +66,19 @@ public void checkLegalityBeforeTypeCoercion() {
             throw new AnalysisException("the time unit parameter of "
                     + getName() + " function must be a string constant: " + toSql());
         } else if (firstArgIsStringLiteral && secondArgIsStringLiteral) {
-            if (!LEGAL_TIME_UNIT.contains(((StringLikeLiteral) getArgument(0)).getStringValue().toLowerCase())
-                    && !LEGAL_TIME_UNIT.contains(((StringLikeLiteral) getArgument(1))
-                    .getStringValue().toLowerCase())) {
+            StringLikeLiteral argument0 = (StringLikeLiteral) getArgument(0);
+            StringLikeLiteral argument1 = (StringLikeLiteral) getArgument(1);
+            if (!LEGAL_TIME_UNIT.contains(argument0.getStringValue().toLowerCase())
+                    && !(argument0 instanceof PlaceholderLiteral)
+                    && !LEGAL_TIME_UNIT.contains(argument1.getStringValue().toLowerCase())
+                    && !(argument1 instanceof PlaceholderLiteral)) {
                 throw new AnalysisException("date_trunc function time unit param only support argument is "
                         + String.join("|", LEGAL_TIME_UNIT));
             }
         } else {
-            final String constParam = ((StringLikeLiteral) getArgument(firstArgIsStringLiteral ? 0 : 1))
-                    .getStringValue().toLowerCase();
-            if (!LEGAL_TIME_UNIT.contains(constParam)) {
+            StringLikeLiteral argument = (StringLikeLiteral) getArgument(firstArgIsStringLiteral ? 0 : 1);
+            final String constParam = argument.getStringValue().toLowerCase();
+            if (!LEGAL_TIME_UNIT.contains(constParam) && !(argument instanceof PlaceholderLiteral)) {
                 throw new AnalysisException("date_trunc function time unit param only support argument is "
                         + String.join("|", LEGAL_TIME_UNIT));
             }

fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/literal/PlaceholderLiteral.java

@@ -0,0 +1,33 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package org.apache.doris.nereids.trees.expressions.literal;
+
+/**
+ * Placeholder literal only used for prepare stage.
+ */
+public class PlaceholderLiteral extends StringLiteral {
+
+    /**
+     * Constructor for Literal.
+     *
+     * @param value real value stored in java object
+     */
+    public PlaceholderLiteral(String value) {
+        super(value);
+    }
+}

regression-test/data/prepared_stmt_p0/prepared_stmt.out

@@ -142,6 +142,12 @@ a
 0	1
 1	2
 
+-- !select27 --
+2025-01-01T00:00
+
+-- !select28 --
+2020-01-01T00:00
+
 -- !overflow_2 --
 2
 

regression-test/suites/prepared_stmt_p0/prepared_stmt.groovy

@@ -356,6 +356,26 @@ suite("test_prepared_stmt", "nonConcurrent") {
         stmt_read.setString(2, "2")
         stmt_read.setString(3, "3")
         qe_select26 stmt_read
+
+        sql """drop table if exists date_trunc_test"""
+        sql """ CREATE TABLE IF NOT EXISTS `date_trunc_test` (
+              `pk` int NULL,
+              `value` datetime NOT NULL
+            ) ENGINE=OLAP
+            DUPLICATE KEY(`pk`)
+            DISTRIBUTED BY HASH(`pk`) BUCKETS 10
+            PROPERTIES (
+            "replication_allocation" = "tag.location.default: 1"
+            );
+        """
+        sql """insert into date_trunc_test values (1, "2025-09-21 15:43:25") """
+        stmt_read = prepareStatement "select date_trunc(value, ?) from date_trunc_test"
+        stmt_read.setString(1, "year")
+        qe_select27 stmt_read
+        stmt_read = prepareStatement "select date_trunc(?, ?) from date_trunc_test"
+        stmt_read.setString(1, "year")
+        stmt_read.setString(2, "2020-01-01 11:22:33")
+        qe_select28 stmt_read
     }
 
     // test stmtId overflow