From b08f1580f923b751df7ca6fc4bfa085c82ef286e Mon Sep 17 00:00:00 2001
From: Rob Bygrave <robin.bygrave@gmail.com>
Date: Sat, 3 Dec 2016 15:10:11 +1300
Subject: [PATCH] #910 - SQL Server update - Add ANSI based row limiter (2012+)
 and make as default platform

---
 .../dbplatform/SqlServer2005Platform.java     | 11 +++++
 .../dbplatform/SqlServer2012SqlLimiter.java   | 47 +++++++++++++++++++
 .../dbplatform/SqlServerBasicSqlLimiter.java  | 24 ++++++++++
 .../config/dbplatform/SqlServerPlatform.java  |  3 +-
 4 files changed, 84 insertions(+), 1 deletion(-)
 create mode 100644 src/main/java/com/avaje/ebean/config/dbplatform/SqlServer2005Platform.java
 create mode 100644 src/main/java/com/avaje/ebean/config/dbplatform/SqlServer2012SqlLimiter.java
 create mode 100644 src/main/java/com/avaje/ebean/config/dbplatform/SqlServerBasicSqlLimiter.java

diff --git a/src/main/java/com/avaje/ebean/config/dbplatform/SqlServer2005Platform.java b/src/main/java/com/avaje/ebean/config/dbplatform/SqlServer2005Platform.java
new file mode 100644
index 000000000..8d631acb3
--- /dev/null
+++ b/src/main/java/com/avaje/ebean/config/dbplatform/SqlServer2005Platform.java
@@ -0,0 +1,11 @@
+package com.avaje.ebean.config.dbplatform;
+
+/**
+ * SQL Server platform using the older ROW_NUMBER() mechanism.
+ */
+public class SqlServer2005Platform extends SqlServerPlatform {
+
+  public SqlServer2005Platform() {
+    this.sqlLimiter = new SqlServer2005SqlLimiter();
+  }
+}
diff --git a/src/main/java/com/avaje/ebean/config/dbplatform/SqlServer2012SqlLimiter.java b/src/main/java/com/avaje/ebean/config/dbplatform/SqlServer2012SqlLimiter.java
new file mode 100644
index 000000000..9eb9104f0
--- /dev/null
+++ b/src/main/java/com/avaje/ebean/config/dbplatform/SqlServer2012SqlLimiter.java
@@ -0,0 +1,47 @@
+package com.avaje.ebean.config.dbplatform;
+
+/**
+ * Use ANSI offset rows syntax or top n.
+ */
+public class SqlServer2012SqlLimiter implements SqlLimiter {
+
+  public SqlServer2012SqlLimiter() {
+  }
+
+  public SqlLimitResponse limit(SqlLimitRequest request) {
+
+    String dbSql = request.getDbSql();
+    StringBuilder sb = new StringBuilder(50 + dbSql.length());
+
+    int firstRow = request.getFirstRow();
+    int maxRows = request.getMaxRows();
+
+    if (firstRow < 1) {
+      // just use top n
+      sb.append("select ");
+      if (request.isDistinct()) {
+        sb.append("distinct ");
+      }
+      sb.append("top ").append(maxRows).append(" ");
+      sb.append(dbSql);
+      return new SqlLimitResponse(sb.toString(), false);
+    }
+
+    sb.append("select ");
+    if (request.isDistinct()) {
+      sb.append("distinct ");
+    }
+
+    sb.append(dbSql);
+    if (firstRow > 0) {
+      sb.append(" ").append("offset");
+      sb.append(" ").append(firstRow).append(" rows");
+    }
+    if (maxRows > 0) {
+      sb.append(" fetch next ").append(maxRows).append(" rows only");
+    }
+    String sql = sb.toString();
+    return new SqlLimitResponse(sql, false);
+  }
+
+}
diff --git a/src/main/java/com/avaje/ebean/config/dbplatform/SqlServerBasicSqlLimiter.java b/src/main/java/com/avaje/ebean/config/dbplatform/SqlServerBasicSqlLimiter.java
new file mode 100644
index 000000000..245fcc449
--- /dev/null
+++ b/src/main/java/com/avaje/ebean/config/dbplatform/SqlServerBasicSqlLimiter.java
@@ -0,0 +1,24 @@
+package com.avaje.ebean.config.dbplatform;
+
+/**
+ * SQL Server 2012 style limiter for raw sql.
+ */
+public class SqlServerBasicSqlLimiter implements BasicSqlLimiter {
+
+  @Override
+  public String limit(String dbSql, int firstRow, int maxRows) {
+
+    StringBuilder sb = new StringBuilder(50 + dbSql.length());
+    sb.append(dbSql);
+    if (!dbSql.toLowerCase().contains("order by")) {
+      sb.append(" order by 1 ");
+    }
+    sb.append(" ").append("offset");
+    sb.append(" ").append(firstRow).append(" rows");
+    if (maxRows > 0) {
+      sb.append(" fetch next ").append(maxRows).append(" rows only");
+    }
+    return sb.toString();
+  }
+
+}
diff --git a/src/main/java/com/avaje/ebean/config/dbplatform/SqlServerPlatform.java b/src/main/java/com/avaje/ebean/config/dbplatform/SqlServerPlatform.java
index 2590dba2f..a31dca29a 100644
--- a/src/main/java/com/avaje/ebean/config/dbplatform/SqlServerPlatform.java
+++ b/src/main/java/com/avaje/ebean/config/dbplatform/SqlServerPlatform.java
@@ -16,7 +16,8 @@ public class SqlServerPlatform extends DatabasePlatform {
     this.persistBatchOnCascade = PersistBatch.NONE;
     this.idInExpandedForm = true;
     this.selectCountWithAlias = true;
-    this.sqlLimiter = new SqlServer2005SqlLimiter();
+    this.sqlLimiter = new SqlServer2012SqlLimiter();
+    this.basicSqlLimiter = new SqlServerBasicSqlLimiter();
     this.platformDdl = new MsSqlServerDdl(this);
     this.dbIdentity.setIdType(IdType.IDENTITY);
     this.dbIdentity.setSupportsGetGeneratedKeys(true);