Channi Studies

A JOIN clause is used to combine rows from two or more tables, based on a related column between them.We will take a look into INNER JOIN, LEFT JOIN, and RIGHT JOIN.  Continued from the previous post, customers table consists of 3 columns: customer_id (PRIMARY KEY), first_name, last_nametransactions table consists of 3 columns: transaction_id (PRIMARY KEY), amount, customer_id (FOREIGN KEY)INSER..

Double Hashing is an open-addressing collision resolution technique that uses 2 different hash functions to compute bucket indices. Using hash functions h₁ and h₂, a key's index in the table is computed with the formula (h₁(key) + 𝑖 * h₂(key)) mod (tablesize) Inserting a key uses the formula, starting with 𝑖 = 0, repeatedly search hash table buckets until an empty bucket is found.Each time an ..

Linear Probing A hash table with linear probing handles a collision by starting at the key's mapped bucket, and then linearly searches subsequent buckets until an empty bucket is found.  Item 124 should be inserted into bucket 4 since 124 % 10 = 4, but bucket 4 is already occupied, so it searched for next null (empty) bucket appearing linearly starting from the original bucket. Since bucket 5 wa..

Hash TableA hash table is data structure that stores unordered items by mapping (or hashing) each item to a location in an array (or vector).Ex. Given an array with indices 0 ... 9 to store integers from 0 ... 5000, the modulo (remainder) operator can b usd to map 25 to index 5 (25 % 10 = 5), and 149 to index 9 (149 % 10 = 9). A hash table's main advantage is that searching, inserting, and remov..