Use of the ltrim () function for left-side Oracle Cropping

First look at the example

Example 1: select ltrim ('caolingxiong ', 'cao') from dual;

------ The returned result is ----------

Lingxiong

This result is expected because the beginning of the first parameter is the same as that of the second parameter, so cao is cropped.

Let's take a look at the example below

Example 2: select ltrim ('oss lingxiong ', 'cao') from dual;

------ The returned result is ----------

Lingxiong

According to our previous understanding, oac and cao are different! Why not intercept it?

The real cropping rule is like this.

Ltrim left crop:

The first character of the first parameter matches each character of the second parameter,

If the match is successful, the crop is cropped and the next character is matched. If the match is unsuccessful, the crop is interrupted.