Search data from multiple table - php

Question

I have 2 table
Table-1 - user
user(ID.Name,Class)
Table-2 - Category
Category(ID,user_id,cat_id)
if user input a data from text field the how to search data from both table

Answer 1

Just query both tables and use the 'OR' operator for the columns you want to search in
SELECT * from user, category WHERE user.id=[text field] or category.user_id=[text field] or category.cat_id=[text field]
PHP Example: (assuming you are using MySQL database - you also need mysqli enabled in your php.ini file)
$mysqli = mysqli_connect(HOSTNAME, USERNAME, PASSWORD, DATABASE);
if (mysqli_connect_errno($mysqli)) {throw new exception("Failed to connect to MySQL: " . mysqli_connect_error());}
$sql = " SELECT * from user, category WHERE user.id='".$text_field."' or category.user_id='".$text_field."' or category.cat_id='".$text_field."'";
$rows = $result->fetch_array(MYSQLI_ASSOC);
foreach($rows as $row){
print_r($row);
}
This should get the records and show you the response from the array.

Answer 2

I hope you have added primary key & foreign key relations to these tables, in-order to grab data from both the tables you have two ways, either do multiplication of both table and bring in all the data else make use of JOIN that does the same in efficient way
Hoping to have your table schema as
USER [table] having id, username, name, password
CATEGORY [table] having id, name, description, user_id
So the query will become
SELECT U.*, C.id as cat_id, C.name as cat_name, C.description as cat_desc
FROM USER U
JOIN CATEGORY C ON C.user_id = U.id
If you have user inputting data from input fields, that becomes a filter query to be added in our above query, assume user is entering Name of category and wants the result set of the same then the above query gets added with WHERE clause as below
WHERE C.name LIKE '%{INPUT FIELD CONTENT HERE}%'
I have used LIKE clause above to allow us doing PARTIAL search
Hope this helps you