Tags » Primary Key

SQL - Constraints

Constraint can be applied to specify rules on a database. There are many constraints but we will only discuss the most commonly used in this blog post. 248 more words

SQL Learning

Constraints in database

Explanation of Constraints:

Not Null
The NOT NULL constraint enforces a column to NOT accept NULL values.
This enforces a field to always contain a value, which means that you cannot insert a new record, or update a record without adding a value to this field. 228 more words


Week 8 - Muddiest Point

Vector space model is something that I have heard of before, but it was just in brief passing. We never spent a large amount of time on it. 82 more words

Muddiest Point

Week 3 - Muddiest Point

So I have used a content management system to develop and maintain the website for the office I used to work at. I understand the basic concept that the CMS is used to organize and disseminate information amongst its various other features. 122 more words

Muddiest Point

Normalization in Data Modelling

Functional Dependency

Functional dependency (FD) is a set of constraints between two attributes in a relation. Functional dependency says that if two tuples have same values for attributes A1, A2,…, An, then those two tuples must have to have same values for attributes B1, B2, …, Bn. 1,188 more words

Cassandra node vs partition: A simple explanation

As explained in How does Cassandra store data? – A simple explanation Cassandra uses partitioning key (the first part of primary key) to store a record into a partition on a node. 141 more words


Migrating SQL applications to Cassandra – Pattern #4

Pattern #4: Get rid of all OR operators from sql where clauses. For example, consider an SQL requirement to authenticate user by comparing the string entered by the user with either username… 76 more words