Oracle indexOf Function Explained

1 year ago
Ava Mitchell
2 minutes

In Oracle databases, an index is a data structure used to enhance query performance. Indexes are created based on the values of one or more table columns, allowing the database engine to locate and access data in the table more quickly.

The indexOf function does not exist in Oracle database, but if you are referring to a custom function in PL/SQL, it may be used to locate the position of a substring within a string.

原文：我每天早上去跑步。

Paraphrased: I go for a run every morning.

CREATE OR REPLACE FUNCTION indexOf(p_string1 IN VARCHAR2, p_string2 IN VARCHAR2)
  RETURN NUMBER
IS
BEGIN
  RETURN INSTR(p_string1, p_string2);
END;
/

The function mentioned above takes two string parameters: p_string1 is the string to be searched and p_string2 is the substring to be found. The function uses the built-in INSTR function to return the position of the substring within the main string. If the substring does not exist, it returns 0.

Example of using the indexOf function:

DECLARE
  position NUMBER;
BEGIN
  position := indexOf('Hello World', 'World');
  DBMS_OUTPUT.PUT_LINE('Position: ' || position);
END;
/

The example above will output “Position: 7” because the substring “World” begins at the 7th character in the main string “Hello World”.

Please note that the indexOf function only returns the position of the first occurrence of a substring. If you need to find the position of all occurrences, you will need to use a different method.

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