oracle中substr函数的用法

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本文介绍了 Oracle 中 SUBSTR 函数的基本用法及其参数设置。SUBSTR 函数可以从字符串中提取子串，支持指定起始位置及长度，还支持从字符串末尾开始计算位置。

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'