Rownum strange behaviour

From: mRangel <marcus.rangel_at_gmail.com>
Date: 21 May 2007 06:57:15 -0700
Message-ID: <1179755835.514338.171910@b40g2000prd.googlegroups.com>

I am trying to write a little piece of code to get "any record" from a table (for testing purposes). I wrote the following:

SQL> select count(1) from user_objects;

  COUNT(1)

---

       617

SQL> select inv.object_name
  2 from ( select rownum idx, object_name from user_objects ) inv   3 where inv.idx = 1 + trunc(dbms_random.value * 600)   4 /

Much to my surprise, as you can see below, the number of lines returned varies from 0 to N ! How is it possible ? Can ROWNUM be repeated inside the inline view ? I am using Oracle 10.2.0.3 under RH linux.

OBJECT_NAME

---

HR_CODIF_OPER_RESUMO
IDX_PERF0015 SQL> / OBJECT_NAME

---

WB_MI_TMP_DUPLICS SQL> / OBJECT_NAME

---

SQL> / OBJECT_NAME

---

SQL> / OBJECT_NAME

---

DBG$$$_SPLIT_3_GRP1
IDX_PERF0066
MR_PESSOAS_JURIDICAS SQL> / OBJECT_NAME

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WB_HOUR12MI_SS SQL> / OBJECT_NAME

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MG_FERIADOS
IDX_PERF0072 Received on Mon May 21 2007 - 08:57:15 CDT