In Oracle, instr functions are similar to indexof.

No indexof () function in Oracle
However, an instr () method is provided for specific usage:
Select instr ('South city of Baoding City ', 'city', 1, 1)-1 from dual;
Explanation: 1. 'baoding City South region' => it can be an expression or a specific data
2. 'city' => is the separator. Here is the word "city" in the two groups of data.
3. The first 1 starts from the left. If it is-1, it starts from the right.
4. The second one is the number of times the city appears.


In GBK encoding, a Chinese character occupies two bytes.
Select instr ('baoding city nanshicheng district ', 'city',) from dual; the value is 5
Select instr ('baoding city nanshicheng district ', 'city', 1, 2) from dual; the value is 9

Select instr ('baoding city nanshicheng district ', 'city',-) from dual; the value is 9
Select instr ('baoding city South', 'city',-1, 2) from dual; the value is 5