php - PDO prepared select statement -

i have been tasked search database using pdo prepared select statement have been given looks this

select * ? ? = '?' 

i have managed pdo conduct search totally incorrect, ive tried use examples have seen on here nothing seems job here how temp fixed search me

try {  //create array of prepared sql commands select * db tables avoiding sql injection $sql = $dbh->prepare("show tables");  $sql->execute();  if ( $sql->columncount() > 0 ) {   while ($row = $sql->fetch() )   //$sqls[ $row[0] ] = "select * " . $row[0] . ";";     $sqls[ $row[0] ] = "select * " . $row[0] . " $fieldname = '?';";     $sql = $dbh->prepare($sqls[$tablename]);     $sql->execute() } 

and here attempt use "?"

try {  //create array of prepared sql commands select * db tables avoiding sql injection $sql = $dbh->prepare("show tables");  $sql->execute();  if ( $sql->columncount() > 0 ) {   while ($row = $sql->fetch() )   //$sqls[ $row[0] ] = "select * " . $row[0] . ";";     $sqls[ $row[0] ] = "select * ? '?' = '?';";     $sql = $dbh->prepare($sqls[$tablename]);     $sql->bindparam(1,$tablename);     $sql->bindparam(2,$fieldname);     $sql->bindparam(3,$celldata);     $sql->execute() } 

this of course didn't work, tried 's' method bind parameter didn't work either know there's [ $row[0] ] understand goes first row of table, not understand fits in goal of creating this

select * ? ? = '?' 

any or pointers in right direction appreciated, thank