From 7bfacb095b0de1d39bccb54325272c7774dfac1b Mon Sep 17 00:00:00 2001
From: Robin Bygrave <robin.bygrave@gmail.com>
Date: Mon, 1 Mar 2021 22:47:34 +1300
Subject: [PATCH] #2181 - Oracle 9,10,11 rownum based limiting for SqlQuery and
 DtoQuery (rather than Oracle 12g row limiting)

---
 .../dbplatform/oracle/Oracle11Platform.java   |  1 +
 .../oracle/OracleRownumBasicLimiter.java      | 35 +++++++++++++++++++
 2 files changed, 36 insertions(+)
 create mode 100644 ebean-api/src/main/java/io/ebean/config/dbplatform/oracle/OracleRownumBasicLimiter.java

diff --git a/ebean-api/src/main/java/io/ebean/config/dbplatform/oracle/Oracle11Platform.java b/ebean-api/src/main/java/io/ebean/config/dbplatform/oracle/Oracle11Platform.java
index e13155f3f..cb32a7470 100644
--- a/ebean-api/src/main/java/io/ebean/config/dbplatform/oracle/Oracle11Platform.java
+++ b/ebean-api/src/main/java/io/ebean/config/dbplatform/oracle/Oracle11Platform.java
@@ -13,6 +13,7 @@ public class Oracle11Platform extends OraclePlatform {
     this.platform = Platform.ORACLE11;
     this.columnAliasPrefix = "c";
     this.sqlLimiter = new OracleRownumSqlLimiter();
+    this.basicSqlLimiter = new OracleRownumBasicLimiter();
     dbIdentity.setIdType(IdType.SEQUENCE);
   }
 }
diff --git a/ebean-api/src/main/java/io/ebean/config/dbplatform/oracle/OracleRownumBasicLimiter.java b/ebean-api/src/main/java/io/ebean/config/dbplatform/oracle/OracleRownumBasicLimiter.java
new file mode 100644
index 000000000..e51df98cb
--- /dev/null
+++ b/ebean-api/src/main/java/io/ebean/config/dbplatform/oracle/OracleRownumBasicLimiter.java
@@ -0,0 +1,35 @@
+package io.ebean.config.dbplatform.oracle;
+
+import io.ebean.config.dbplatform.BasicSqlLimiter;
+
+/**
+ * Row limiter for Oracle 9,10,11 using rownum.
+ */
+public class OracleRownumBasicLimiter implements BasicSqlLimiter {
+
+  @Override
+  public String limit(String dbSql, int firstRow, int maxRows) {
+    if (firstRow < 1 && maxRows < 1) {
+      return dbSql;
+    }
+    StringBuilder sb = new StringBuilder(60 + dbSql.length());
+    int lastRow = maxRows;
+    if (lastRow > 0) {
+      lastRow += firstRow;
+    }
+    sb.append("select * from (select ");
+    if (maxRows > 0) {
+      sb.append("/*+ FIRST_ROWS(").append(maxRows).append(") */ ");
+    }
+    sb.append("a.*, rownum rn_ from (");
+    sb.append(dbSql).append(") a ");
+    if (lastRow > 0) {
+      sb.append(" where rownum <= ").append(lastRow);
+    }
+    sb.append(") ");
+    if (firstRow > 0) {
+      sb.append(" where rn_ > ").append(firstRow);
+    }
+    return sb.toString();
+  }
+}