Enable .take without .drop for MS SQL

Use `SELECT TOP(?) ...` for MS SQL when there's no offset.

Author: kiendang

scalasql/src/dialects/MsSqlDialect.scala

@@ -168,7 +168,9 @@ object MsSqlDialect extends MsSqlDialect {
         groupBy0
       )
       with Select[Q, R] {
-        override def take(n: Int): scalasql.query.Select[Q,R] = throw new Exception(".take must follow .sortBy")
+        override def take(n: Int): scalasql.query.Select[Q,R] = {
+          selectWithExprPrefix(true, _ => sql"TOP($n)")
+        }
 
         override def drop(n: Int): scalasql.query.Select[Q,R] = throw new Exception(".drop must follow .sortBy")
       }

scalasql/test/src/dialects/MsSqlDialectTests.scala

@@ -1,11 +1,26 @@
 package scalasql.dialects
 
 import scalasql._
+import sourcecode.Text
 import utest._
 import utils.MsSqlSuite
 
 trait MsSqlDialectTests extends MsSqlSuite {
   def description = "Operations specific to working with Microsoft SQL Databases"
 
-  def tests = Tests {}
+  def tests = Tests {
+
+    test("top") - checker(
+      query = Buyer.select.take(0),
+      sql = """
+        SELECT TOP(?) buyer0.id AS id, buyer0.name AS name, buyer0.date_of_birth AS date_of_birth
+        FROM buyer buyer0
+      """,
+      value = Seq[Buyer[Sc]](),
+      docs = """
+        For ScalaSql's Microsoft SQL dialect provides, the `.take(n)` operator translates
+        into a SQL `TOP(n)` clause
+      """
+    )
+  }
 }