How does PHP query the SQL loaded variable table?

PHP: How to query SQL loaded variable tables such as selecting a line & nbsp; & nbsp; & lt; select & nbsp; namexianlu & gt; & nbsp; & nbsp; & How does nb PHP query the SQL loaded variable table?
How does PHP query the SQL loaded variable table? for example:


Select line
203 207 213 214 225 283

Select different lines to load tables that do not understand
This is the original sentence,
$ Q = "SELECT * FROM 'line' left join research2 on line. busname = research2.busname WHERE banben is NULL or banben like '% {$ _ REQUEST ['banben']} % '";

An error is reported after modification based on the original sentence.
$ Q = "SELECT * FROM'' % {$ _ REQUEST ['xianlu']} % ''left join research2 on '% {$ _ REQUEST ['xianlu']} % '. busname = research2.busname WHERE banben is NULL or banben like '% {$ _ REQUEST ['banben']} % '";

------ Solution ----------------------
$ Q = "SELECT * FROM '{$ _ REQUEST ['xianlu']} 'left JOIN research2 on' {$ _ REQUEST ['xianlu']} '. busname = research2.busname WHERE banben is NULL or banben like '% {$ _ REQUEST ['banben']} % '";