CODEWITHSUNDEEP
sqlsqlite
J0HN_TIT0R
J0HN_TIT0R

Reputation: 323

How to perform an SQL query from a table based on values in other tables?

This is a pretty basic problem, but I'm new to SQL so it's giving me trouble.

Say I have three tables: X, Y, and Z.

X contains foreign keys for Y, and Y contains foreign keys for Z. How can I select all rows in X which have foreign keys for Y, which in turn have foreign keys for Z, which in turn match some specified value?

For example lets say that these are the columns for each table:

X = "x_ids", "x_values", "y_foreign_keys"

Y = "y_ids", "y_values", "z_foreign_keys"

Z = "z_ids", "z_values"

I need to find out how to select all rows of X which I can trace down to z_values which equal the string "test".

Upvotes: 0

Views: 57

Answers (1)

Katz
Katz

Reputation: 156

Can you try this:

Tables

X = "x_ids", "x_values", "y_foreign_keys"

Y = "y_ids", "y_values", "z_foreign_keys"

Z = "z_ids", "z_values"

SQL

SELECT * FROM Z 
INNER JOIN Y ON z_ids = z_foreign_keys
INNER JOIN X ON y_ids = y_foreign_keys WHERE X.x_values= 'HELLO WORLD';

Upvotes: 1

Related Questions