From 7f723e1e107c747cef98a90986021f4bcf69f904 Mon Sep 17 00:00:00 2001
From: Christiaan Westerbeek <chris@devotis.nl>
Date: Mon, 11 May 2015 10:40:39 +0200
Subject: [PATCH] Add support for SELECT TOP construct for mssql dialect for
 limit

---
 lib/Dialects/mssql.js                       |  2 ++
 lib/Remove.js                               | 25 +++++++++++++--------
 lib/Select.js                               | 23 ++++++++++++-------
 test/integration/test-dialect-mssql.js      |  6 +++++
 test/integration/test-dialect-mysql.js      |  6 +++++
 test/integration/test-dialect-postgresql.js |  6 +++++
 test/integration/test-dialect-sqlite.js     |  6 +++++
 7 files changed, 57 insertions(+), 17 deletions(-)

diff --git a/lib/Dialects/mssql.js b/lib/Dialects/mssql.js
index 69a3ada..e49f592 100644
--- a/lib/Dialects/mssql.js
+++ b/lib/Dialects/mssql.js
@@ -66,3 +66,5 @@ exports.escapeVal = function (val, timeZone) {
 };
 
 exports.defaultValuesStmt = "DEFAULT VALUES";
+
+exports.limitAsTop = true;
diff --git a/lib/Remove.js b/lib/Remove.js
index 6fe367b..cc4aa55 100644
--- a/lib/Remove.js
+++ b/lib/Remove.js
@@ -25,7 +25,12 @@ function RemoveQuery(Dialect, opts) {
 		build: function () {
 			var query = [], tmp;
 
-			query.push("DELETE FROM");
+			// limit as: SELECT TOP n (MSSQL only)
+			if (Dialect.limitAsTop && sql.hasOwnProperty("limit")) {
+				query.push("DELETE TOP " + sql.limit + " FROM");
+			} else {
+				query.push("DELETE FROM");
+			}
 			query.push(Dialect.escapeId(sql.table));
 
 			query = query.concat(Where.build(Dialect, sql.where, opts));
@@ -46,15 +51,17 @@ function RemoveQuery(Dialect, opts) {
 				}
 			}
 
-			// limit
-			if (sql.hasOwnProperty("limit")) {
-				if (sql.hasOwnProperty("offset")) {
-					query.push("LIMIT " + sql.limit + " OFFSET " + sql.offset);
-				} else {
-					query.push("LIMIT " + sql.limit);
+			// limit for all Dialects but MSSQL
+			if (!Dialect.limitAsTop) {
+				if (sql.hasOwnProperty("limit")) {
+					if (sql.hasOwnProperty("offset")) {
+						query.push("LIMIT " + sql.limit + " OFFSET " + sql.offset);
+					} else {
+						query.push("LIMIT " + sql.limit);
+					}
+				} else if (sql.hasOwnProperty("offset")) {
+					query.push("OFFSET " + sql.offset);
 				}
-			} else if (sql.hasOwnProperty("offset")) {
-				query.push("OFFSET " + sql.offset);
 			}
 
 			return query.join(" ");
diff --git a/lib/Select.js b/lib/Select.js
index 205b9b7..a06ef03 100644
--- a/lib/Select.js
+++ b/lib/Select.js
@@ -210,6 +210,11 @@ function SelectQuery(Dialect, opts) {
 
 			query.push("SELECT");
 
+			// limit as: SELECT TOP n (MSSQL only)
+			if (Dialect.limitAsTop && sql.hasOwnProperty("limit")) {
+				query.push("TOP " + sql.limit);
+			}
+
 			for (i = 0; i < sql.from.length; i++) {
 				sql.from[i].a = "t" + (i + 1);
 			}
@@ -399,15 +404,17 @@ function SelectQuery(Dialect, opts) {
 				}
 			}
 
-			// limit
-			if (sql.hasOwnProperty("limit")) {
-				if (sql.hasOwnProperty("offset")) {
-					query.push("LIMIT " + sql.limit + " OFFSET " + sql.offset);
-				} else {
-					query.push("LIMIT " + sql.limit);
+			// limit for all Dialects but MSSQL
+			if (!Dialect.limitAsTop) {
+				if (sql.hasOwnProperty("limit")) {
+					if (sql.hasOwnProperty("offset")) {
+						query.push("LIMIT " + sql.limit + " OFFSET " + sql.offset);
+					} else {
+						query.push("LIMIT " + sql.limit);
+					}
+				} else if (sql.hasOwnProperty("offset")) {
+					query.push("OFFSET " + sql.offset);
 				}
-			} else if (sql.hasOwnProperty("offset")) {
-				query.push("OFFSET " + sql.offset);
 			}
 
 			return query.join(" ");
diff --git a/test/integration/test-dialect-mssql.js b/test/integration/test-dialect-mssql.js
index 1542b7e..b737bbb 100644
--- a/test/integration/test-dialect-mssql.js
+++ b/test/integration/test-dialect-mssql.js
@@ -98,3 +98,9 @@ assert.equal(
   dialect.defaultValuesStmt,
   "DEFAULT VALUES"
 );
+
+//Assert that mssql is configured to use the SELECT TOP as a contruct for limit
+assert.equal(
+  dialect.limitAsTop,
+  true
+);
\ No newline at end of file
diff --git a/test/integration/test-dialect-mysql.js b/test/integration/test-dialect-mysql.js
index f174c70..fa7b836 100644
--- a/test/integration/test-dialect-mysql.js
+++ b/test/integration/test-dialect-mysql.js
@@ -98,3 +98,9 @@ assert.equal(
 	dialect.defaultValuesStmt,
 	"VALUES()"
 );
+
+//For all dialects but mssql limitAsTop should be undefined or false
+assert.equal(
+  dialect.limitAsTop || false,
+  false
+);
\ No newline at end of file
diff --git a/test/integration/test-dialect-postgresql.js b/test/integration/test-dialect-postgresql.js
index 685b7f0..8fd1e30 100644
--- a/test/integration/test-dialect-postgresql.js
+++ b/test/integration/test-dialect-postgresql.js
@@ -103,3 +103,9 @@ assert.equal(
 	dialect.defaultValuesStmt,
 	"DEFAULT VALUES"
 );
+
+//For all dialects but mssql limitAsTop should be undefined or false
+assert.equal(
+  dialect.limitAsTop || false,
+  false
+);
\ No newline at end of file
diff --git a/test/integration/test-dialect-sqlite.js b/test/integration/test-dialect-sqlite.js
index d25e72e..5327706 100644
--- a/test/integration/test-dialect-sqlite.js
+++ b/test/integration/test-dialect-sqlite.js
@@ -98,3 +98,9 @@ assert.equal(
 	dialect.defaultValuesStmt,
 	"DEFAULT VALUES"
 );
+
+//For all dialects but mssql limitAsTop should be undefined or false
+assert.equal(
+  dialect.limitAsTop || false,
+  false
+);
\ No newline at end of file