ruby rails where not in

To perform a "where not in" query in Ruby on Rails, you can use the .where.not method. Here are the steps to perform this query:

  1. Start by writing the base query using the model you want to query. For example, if you have a User model, you can start with:

ruby User.where.not(...)

  1. Inside the .where.not method, you need to specify the condition for the "not in" query. This condition typically involves a column name and an array of values that you want to exclude. For example, if you want to find users whose IDs are not in the array [1, 2, 3], you can write:

ruby User.where.not(id: [1, 2, 3])

This will generate a SQL query that looks like:

sql SELECT * FROM users WHERE (users.id NOT IN (1, 2, 3))

The NOT IN operator is used to exclude the specified values from the query results.

  1. You can add more conditions to the query by chaining additional .where.not or .where methods. For example, if you want to also exclude users whose names are not in the array ['John', 'Jane'], you can write:

ruby User.where.not(id: [1, 2, 3]).where.not(name: ['John', 'Jane'])

This will generate a SQL query that looks like:

sql SELECT * FROM users WHERE (users.id NOT IN (1, 2, 3)) AND (users.name NOT IN ('John', 'Jane'))

The AND operator is used to combine multiple conditions.

  1. Finally, you can execute the query and retrieve the results. You can use methods like .first to retrieve the first matching record or .all to retrieve all matching records. For example:

ruby users = User.where.not(id: [1, 2, 3]).where.not(name: ['John', 'Jane']).all

This will execute the SQL query and return an array of User objects that match the conditions.

That's it! You have now performed a "where not in" query in Ruby on Rails using the .where.not method.