Solving problems related to intra-site search

There are several small questions about intra-site search. please help me explain the keyword of an order. I don't need to say that it is mainly multi-keyword, is it necessary to split keywords into arrays during multi-keyword search? If it is split into arrays (the length of the array cannot be determined, because you do not know how many keywords the user will enter), then the SQL statement is used to solve the problem of intra-site search.
I have several questions about intra-site search. could you please help me explain?

A single keyword is not required. it is mainly a multi-Keyword. do you want to split keywords into arrays during multi-keyword search? If it is split into an array (the length of the array cannot be determined, because the user does not know how many keywords will be entered), how to write the where statement in SQL?

The tutorial I read is written in this way.

$ SQL = select * from bbs where title like '% $ array [0] %' or content like '% $ array [1] % ';

If this is the case, wouldn't $ array [1] in title and $ array [0] in content be searched?

------ Solution --------------------
For small data volumes, you can:
Assume that you enter a bunch of keywords and divide them into arrays by spaces (or commas ).
$ SQL = select * from tablename where 1 = 1
Foreach ($ array as $ value)
{
$ SQL. = and title like '% $ value %' or content like '% $ value %'
}
If the blogger's SQL statements run with tens of thousands of records, it will be quite difficult.

The like query in the database facilitates all table records, and the time complexity is O (n)
If there is a large amount of data, consider splitting the title content. use hash table O1 to find the primary key of the corresponding table, and then query it from the database.