CODEWITHSUNDEEP
mysqlselect
frank
frank

Reputation: 303

MySQL select where equal to multiple values

I have two databases, where I store who is following who and another which stores the posts the user makes.

I want to select all of the people a user is following from the following database and echo out the usernames of those who that user is following and query the posts database for posts of that user.

My problem is what if a user is following multiple users, I echoed out of the user id's of the people this user is following and I get 44443344330

When I separate each id with commans, I get:

44,44,33,44,33,0,

so let's give that a variable of $user_ids;

$user_ids = "44,44,33,44,33,0, ";

the query:

$get_posts = mysql_query("SELECT * FROM posts WHERE userid = '$user_ids'");

but all it does is show the records of the first user id, 44.

How can I retrieve all of the records for all the users?

Upvotes: 30

Views: 81824

Answers (6)

Callum
Callum

Reputation: 41

Given that you have two tables, not two databases, the easiest way to match multiple values for a specific column would be the following:

SELECT * FROM posts WHERE userid IN (44,44,33,44,33,0)

*A small point that I ran into when doing this. If you are matching to a column that is of type VARCHAR(n), be sure to wrap your matching values in 'single quotes', not "double quotes"

e.g:

SELECT * FROM posts WHERE name IN ('foo','bar','alpha','beta')

Upvotes: 4

james_bond
james_bond

Reputation: 6908

Maybe you want to use IN

SELECT * FROM posts WHERE userid IN ($user_ids)

Upvotes: 28

Ethilé Landry Tanon Abédjinan
Ethilé Landry Tanon Abédjinan

Reputation: 1

$var= str_replace(","," or userid = ","userid =$your_data_from_db");

your myqsl_query = SELECT * FROM posts where $var

Upvotes: 0

ain
ain

Reputation: 22749

Assuming you have two tabels, not databases, and that the table (lets call it "friends") which describes who is following who is like

table friends(
  userid
  friendid
)

then query to get posts posted by X's friends would be

SELECT
 p.* 
FROM posts p
  JOIN friends f ON(p.userid = f.friendid)
WHERE f.userid = X

Upvotes: 1

Kerrek SB
Kerrek SB

Reputation: 477060

The query should be:

SELECT * FROM posts WHERE userid IN (44,44,33,44,33,0)

However, you may have to rethink your data model and make sure it is normalized, so that you can express this construction directly in the databse without echoing into a comma-separated string.

Why do you have two databases? Do you mean two tables?

Upvotes: 39

Shaun Hare
Shaun Hare

Reputation: 3871

$get_posts = mysql_query("SELECT * FROM posts WHERE userid in '($user_ids)'");

Upvotes: 0

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