How to find out whether a string function exists in oracle database

This article mainly introduces "how to find string function in oracle database". In daily operation, I believe that many people have doubts about how to find string function in oracle database. Xiaobian consulted all kinds of information and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubt that "how to find string function in oracle database exists". Next, please follow the editor to study!

INSTR ()

Format 1: instr (string1, string2)

Format 2: instr (string1, string2 [, start_position [, nth_appearance]])

Parsing: the value of string2 is to be found in string1, which is retrieved in string1 from the value given by start_position (that is, location), and the nth _ appearance (several times) string2 appears.

Example:

1 select instr ('helloworld','l') from dual;-return result: 3 default location of "l" for the first time

2 select instr ('helloworld','lo') from dual;-returns the result: 4 that is, in "lo", where the "l" begins to appear

3 select instr ('helloworld','wo') from dual;-returns the result: 6, that is, where "w" begins to appear

4 select instr ('helloworld','l',2,2) from dual;-returns the result: 4 that is, start at position 2 (e) of "helloworld" and find the location of the second occurrence of "l".

Query whether the string exists:

MySQL: select from tableName where name like'% helloworld%'

Oracle:select from tableName where instr (name,'helloworld') > 0;-- the effect of these two statements is the same

Select instr ("helloworld", "l") from dual

The result is: 3 #, that is, the position sequence number of "l" for the first time is 3.

Select instr ("helloworld", "lo") from dual

The result is: 4 #, that is, the position where "lo" appears for the first time is 4

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