php/mysql get all tables and columns in a database - php

Question

i want to check a database and get all table names first and then
show some kind of report from data inside each table
$query = $db3->query("SELECT `table_name` from INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'db3' ") or die("$db3->error");
while ( $table = $query->fetch_assoc() )
{
//echo $table['table_name'].'<br />';
$t = trim($table['table_name']);
//i get all table names now i want to select all columns from that table name :
$select = $db3->query("SELECT * FROM ".$t." ") or die($db3->error);
$row = $select->fetch_assoc();
// checking to see if query worked fine
echo gettype($row);
//it returns NULL
}
am i doing it the right way ?
what should i do ?

Answer 1

For security reasons you should have a whitelist of databases/tables you want to generate reports from. Querying for all tables assumes that all future tables will need to be part of this system.
You can query for the columns in each table using show columns from tableName and iterate the results.

Answer 2

You can use this query in mysql
mysql> SELECT table_name, table_type, engine
-> FROM information_schema.tables
-> WHERE table_schema = 'db5'
-> ORDER BY table_name DESC;

Answer 3

SELECT table_name, column_name FROM Information_schema.columns WHERE table_name like '%example%' ORDER BY table_name DESC
Or you can try this
SELECT table_name, column_name FROM Information_schema.columns WHERE column_name like '%example%' ORDER BY table_name DESC