如何在sql中使用像“爆炸”这样的php方法

Question

I am trying to get some data, and in the table, there is a field named "sysload". However, it is a var(string) type. The data in it is like "0.0, 0.2, 0.5",three numbers split by comma. However, in the sql, I only need the last number(in this example:0.5) to compare in "where". So how can I use it ? My code:

$termquery=mysql_query("SELECT a.terminal FROM terminal_server_log a
inner join
        (
            SELECT  terminal, MAX(timestamp) timestamp
            FROM    terminal_server_log
            group by terminal
        ) b on (b.terminal=a.terminal and a.timestamp=b.timestamp)
WHERE explode(',', sysload)[2]>$number");

The last line is the most important one, i want to compare with '$number', but it seems i cannot use 'explode'. Thanks

Answer 1

You can probably use regular expressions to match the last element of your sysload column: https://dev.mysql.com/doc/refman/8.0/en/regexp.html#function_regexp-instr

Look also at CAST() function, as the extracted substring should be converted to a numeric value to allow comparison with a number.