Fix(tsql): ALTER COLUMN syntax (#5051)

* Addressing spacing for dialects wtihout ALTER_SET_TYPE.

* Set ALTER_SET_TYPE to empty string for tsql generator, with tests.

Author: MarcusRisanger

sqlglot/dialects/tsql.py

@@ -910,6 +910,7 @@ class Generator(generator.Generator):
         COPY_PARAMS_EQ_REQUIRED = True
         PARSE_JSON_NAME = None
         EXCEPT_INTERSECT_SUPPORT_ALL_CLAUSE = False
+        ALTER_SET_TYPE = ""
 
         EXPRESSIONS_WITHOUT_NESTED_CTES = {
             exp.Create,

sqlglot/generator.py

@@ -3346,7 +3346,8 @@ def altercolumn_sql(self, expression: exp.AlterColumn) -> str:
             collate = f" COLLATE {collate}" if collate else ""
             using = self.sql(expression, "using")
             using = f" USING {using}" if using else ""
-            return f"ALTER COLUMN {this} {self.ALTER_SET_TYPE} {dtype}{collate}{using}"
+            alter_set_type = self.ALTER_SET_TYPE + " " if self.ALTER_SET_TYPE else ""
+            return f"ALTER COLUMN {this} {alter_set_type}{dtype}{collate}{using}"
 
         default = self.sql(expression, "default")
         if default:

tests/dialects/test_tsql.py

@@ -1062,6 +1062,16 @@ def test_ddl(self):
                 "tsql": "ALTER TABLE a ADD b INTEGER, c INTEGER",
             },
         )
+        self.validate_all(
+            "ALTER TABLE a ALTER COLUMN b INTEGER",
+            read={
+                "": "ALTER TABLE a ALTER COLUMN b INT",
+            },
+            write={
+                "": "ALTER TABLE a ALTER COLUMN b SET DATA TYPE INT",
+                "tsql": "ALTER TABLE a ALTER COLUMN b INTEGER",
+            },
+        )
         self.validate_all(
             "CREATE TABLE #mytemp (a INTEGER, b CHAR(2), c TIME(4), d FLOAT(24))",
             write={