How to get the first piece of data after sorting in Oracle

Two methods to obtain the first piece of data after sorting in Oracle: use the ROWNUM pseudo column to limit the query to return data with the current row number 1. Use the FETCH FIRST 1 ROWS ONLY clause to limit the query to return only the first 1 row in the result set.

Two methods to obtain the first piece of data after sorting in Oracle

In Oracle, you can use two There are two main ways to get the first piece of data in the sorted data set:

1. Use the ROWNUM pseudo column

ROWNUM pseudo column to return the current The row number in the query result set. The following query uses the ROWNUM pseudo column to obtain the first data of the sorted data set:

SELECT *
FROM (
  SELECT *
  FROM table_name
  ORDER BY column_name
)
WHERE ROWNUM = 1;

2. Use the FETCH FIRST 1 ROWS ONLY clause

FETCH FIRST 1 ROWS ONLY clause limits the query to return only the first 1 row in the result set. The following query uses the FETCH FIRST 1 ROWS ONLY clause to get the first piece of data in the sorted dataset:

SELECT *
FROM table_name
ORDER BY column_name
FETCH FIRST 1 ROWS ONLY;

Example:

Suppose we There is a table named "my_table" that contains the following data:

id	name
1	John
2	Mary
3	Bob

The following query will use the ROWNUM pseudo column to get the first data sorted by the "name" column in ascending order:

SELECT *
FROM (
  SELECT *
  FROM my_table
  ORDER BY name
)
WHERE ROWNUM = 1;

Result:

id	name
1	John

The following query will use the FETCH FIRST 1 ROWS ONLY clause to get the first data sorted by the "name" column in ascending order:

SELECT *
FROM my_table
ORDER BY name
FETCH FIRST 1 ROWS ONLY;

Result:

id	name
1	John

The above is the detailed content of How to get the first piece of data after sorting in Oracle. For more information, please follow other related articles on the PHP Chinese website!