zoukankan      html  css  js  c++  java
  • Oracle/PLSQL: SUBSTR Function-from cyber

    Oracle/PLSQL: SUBSTR Function

    This Oracle tutorial explains how to use the Oracle/PLSQL SUBSTR function with syntax and examples.

    Description

    The Oracle/PLSQL SUBSTR functions allows you to extract a substring from a string.

    Syntax

    The syntax for the SUBSTR function in Oracle/PLSQL is:

    SUBSTR( string, start_position [, length ] )

    Parameters or Arguments

    string
    The source string.
    start_position
    The starting position for extraction. The first position in the string is always 1.
    length
    Optional. It is the number of characters to extract. If this parameter is omitted, the SUBSTR function will return the entire string.

    Note:

    • If start_position is 0, then the SUBSTR function treats start_position as 1 (ie: the first position in the string).
    • If start_position is a positive number, then the SUBSTR function starts from the beginning of the string.
    • If start_position is a negative number, then the SUBSTR function starts from the end of the string and counts backwards.
    • If length is a negative number, then the SUBSTR function will return a NULL value.
    • See also the REGEXP_SUBSTR function.

    Applies To

    The SUBSTR function can be used in the following versions of Oracle/PLSQL:

    • Oracle 12c, Oracle 11g, Oracle 10g, Oracle 9i, Oracle 8i

    Example

    Let's look at some Oracle SUBSTR function examples and explore how to use the SUBSTR function in Oracle/PLSQL.

    For example:

    SUBSTR('This is a test', 6, 2)
    Result: 'is'
    
    SUBSTR('This is a test', 6)
    Result: 'is a test'
    
    SUBSTR('TechOnTheNet', 1, 4)
    Result: 'Tech'
    
    SUBSTR('TechOnTheNet', -3, 3)
    Result: 'Net'
    
    SUBSTR('TechOnTheNet', -6, 3)
    Result: 'The'
    
    SUBSTR('TechOnTheNet', -8, 2)
    Result: 'On'
  • 相关阅读:
    一道经典的JavaScript面试题
    模拟学信网登录,Cookie 序列化,在反序列化之后不能用的问题
    EF搜索数据自动将表名变复数问题
    EF查看sql的方法
    查看当前正在被执行的sql
    mmsql查看最近操作日志
    查询存储过程里面的含有的关键字
    mmsql 查询每个分类的前3条数据
    C# checked关键字当属性
    windows2012 IIS8.5 不能在此路径中使用此配置节
  • 原文地址:https://www.cnblogs.com/Jeffrey-xu/p/4819595.html
Copyright © 2011-2022 走看看