oracle中substr函数的用法

最新推荐文章于 2024-03-19 01:17:07 发布

最新推荐文章于 2024-03-19 01:17:07 发布 · 741 阅读

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本文介绍了 Oracle 数据库中 SUBSTR 函数的使用方法，包括如何从字符串中提取子串，以及如何指定起始位置和长度。通过示例展示了正向和逆向索引的应用。

oracle中substr函数的用法

In oracle/PLSQL, the substr functions allows you to extract a substring from a string.

The syntax for the substr function is:

substr( string, start_position, [ length ] )
说明：
string is the source string.
start_position is the position for extraction. The first position in the string is always 1.
length is optional. It is the number of characters to extract. If this parameter is omitted, substr will return the entire string.

For example:

substr('This is a test', 6, 2) would return 'is'
substr('This is a test', 6) would return 'is a test'
substr('TechOnTheNet', 1, 4) would return 'Tech'
substr('TechOnTheNet', -3, 3) would return 'Net'
substr('TechOnTheNet', -6, 3) would return 'The'
substr('TechOnTheNet', -8, 2) would return 'On'