Oracle 数据库常用指令

Oracle 数据库的学习笔记。

转换成中文环境

ALTER SESSION SET NLS_LANGUAGE = 'SIMPLIFIED CHINESE'

转换成英文环境

ALTER SESSION SET NLS_LANGUAGE = 'AMERICAN'

降序排序

SELECT * FROM TABLE_NAME ORDER BY COLUMN_NAME DESC

升序排序

SELECT * FROM TABLE_NAME ORDER BY COLUMN_NAME ASC

降序排序后选择头两行数据

SELECT *
    FROM (SELECT * FROM TABLE_NAME ORDER BY COLUMN_NAME DESC)
    WHERE ROWNUM <= 2

获取字符串的长度

SELECT (LENGTH(RTRIM(COLUMN_NAME,' ')))
    FROM TABLE_NAME