fix(tsql): use plus operator for string concat to support more systems that use tsql (#4067)

* fix(tsql): use plus operator for string concat to support more systems that use tsql

* Style fixup

---------

Co-authored-by: Jo <[email protected]>

Author: cpcloud

sqlglot/dialects/tsql.py

@@ -3,7 +3,7 @@
 import datetime
 import re
 import typing as t
-from functools import partial
+from functools import partial, reduce
 
 from sqlglot import exp, generator, parser, tokens, transforms
 from sqlglot.dialects.dialect import (
@@ -1192,3 +1192,8 @@ def declareitem_sql(self, expression: exp.DeclareItem) -> str:
         def options_modifier(self, expression: exp.Expression) -> str:
             options = self.expressions(expression, key="options")
             return f" OPTION{self.wrap(options)}" if options else ""
+
+        def dpipe_sql(self, expression: exp.DPipe) -> str:
+            return self.sql(
+                reduce(lambda x, y: exp.Add(this=x, expression=y), expression.flatten())
+            )

tests/dialects/test_tsql.py

@@ -420,6 +420,11 @@ def test_tsql(self):
             "SELECT val FROM (VALUES ((TRUE), (FALSE), (NULL))) AS t(val)",
             write_sql="SELECT val FROM (VALUES ((1), (0), (NULL))) AS t(val)",
         )
+        self.validate_identity("'a' + 'b'")
+        self.validate_identity(
+            "'a' || 'b'",
+            "'a' + 'b'",
+        )
 
     def test_option(self):
         possible_options = [