Get last record of result set

问题

Following is the sql query (oracle) that I use to get the last record of the returning result of the select query. Is this the optimum way?

SELECT HAZMAT_PLACARD_NOTATION
        INTO v_pcn
        FROM HAZMAT_CLASS_IRF
        WHERE HAZMAT_CD = p_stcc_cd and ROWID = (SELECT MAX(ROWID) FROM HAZMAT_CLASS_IRF WHERE HAZMAT_CD = p_stcc_cd);

Following is an example result set of the select query where HAZMAT_CD = 4920111 But the last row with the HAZMAT_PLAYCARD_NOTATION value SPONTANEOUSLY COMBUSTIBLE should be retrieved. That's the objective

enter image description here

回答1:

Get last record of result set

There are many ways:

Oracle Pre-12c version:

ROWNUM in sub-query and ORDER BY in outer query
Analytic function

Oracle 12c version:

Top-n Row Limiting feature

Using ROWNUM

SELECT HAZMAT_PLACARD_NOTATION
INTO v_pcn
FROM
  (SELECT HAZMAT_PLACARD_NOTATION,
    ROWNUM rn
  FROM HAZMAT_CLASS_IRF
  WHERE HAZMAT_CD = p_stcc_cd
  ORDER BY        <sort_column> DESC
  )
WHERE rn =1;

Using Top-n Row Limiting feature

SELECT HAZMAT_PLACARD_NOTATION
 INTO v_pcn
  FROM HAZMAT_CLASS_IRF
  WHERE HAZMAT_CD = p_stcc_cd
  ORDER BY        <sort_column> DESC
FETCH FIRST 1 ROW ONLY;

Have a look at this answer for examples and detailed explanation.

回答2:

In mysql ,you can try this.

SELECT * 
FROM  `table` 
ORDER BY id DESC 
LIMIT 0 , 1

回答3:

In older sqlserver versions (<2014) you don't have the ROW_NUMBER at your disposal.

But you can easily use Top 1 and order by desc

select top 1 * from tblc2scdocumentcodes where C2scDocumentCode like '%.14.%' and C2scDocumentCode like '%DTP.SO.%' order by C2scDocumentCode desc

The query returns a resultset. The order of this resultset is 'reversed' and then limited to 1 record

回答4:

select * from
   ( 
     select * from table order by id desc
   )
where rownum = 1

来源：https://stackoverflow.com/questions/31421549/get-last-record-of-result-set

标签

sql

Oracle

oracle11g