[test](find_in_set) add find_in_set function test case (#20718)

regression-test/data/query_p0/sql_functions/string_functions/test_find_in_set.out

@@ -0,0 +1,13 @@
+-- This file is automatically generated. You should know what you did if you want to edit this
+-- !sql --
+1,2,3	d
+
+-- !sql --
+1 	a
+
+-- !sql --
+\N	c	\N
+1 	a	1
+1,2,3	d	0
+2  	b	0
+

regression-test/suites/query_p0/sql_functions/string_functions/test_find_in_set.groovy

@@ -0,0 +1,39 @@
+// 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.
+
+suite("test_find_in_set") {
+
+    def tbName = "test_find_in_set"
+    sql "DROP TABLE IF EXISTS ${tbName}"
+    sql """
+            CREATE TABLE IF NOT EXISTS ${tbName} (
+                 timea varchar(30)  NULL,
+                 creatr varchar(30) NULL
+            )
+            DISTRIBUTED BY HASH(timea) BUCKETS 5 properties("replication_num" = "1");
+        """
+    sql """
+        INSERT INTO ${tbName} VALUES  ('1 ','a'),('2  ','b'), ('1,2,3','d'),(null,'c');
+        """
+
+    // LIKE as predicate
+    qt_sql "select * from ${tbName} where find_in_set(\"1\", timea) > 0;"
+    qt_sql "select * from ${tbName} where find_in_set(\"1 \", timea) > 0;"
+    qt_sql "select *, find_in_set(\"1 \", timea) from ${tbName} order by 1;"
+
+    sql "DROP TABLE ${tbName};"
+}