Step 1 – Insert USB and Identify Volume $ df -h Filesystem Size Used Avail Use% Mounted on /dev/sda1 28G 24G 2.3G 92% / udev 1.4G 12K 1.4G 1% /dev tmpfs 277M 1.2M 276M 1% /run none 5.0M 0 5.0M 0% /run/lock none 1.4G 34M 1.4G 3% /run/shm /dev/sdc1 14.8G 1.4G 13.4G 10% /media/admin Now, … Read more
SQL language also includes syntax to update, insert, and delete records. These query and update commands together form the Data Manipulation Language (DML) part of SQL: • INSERT INTO – inserts new data into a database table • UPDATE – updates data in a database table • DELETE – deletes data from a database table … Read more
The Data Definition Language (DDL) part of SQL permits database tables to be created or deleted. We can also define indexes (keys), specify links between tables, and impose constraints between database tables. The most important DDL statements in SQL are: • CREATE TABLE – creates a new database table • ALTER TABLE – alters (changes) … Read more
Here you can see that SQL commands follow a number of basic rules: • SQL keywords are not normally case sensitive, though this in this tutorial all commands (SELECT, UPDATE etc) are upper-cased. • Variable and parameter names are displayed here as lower-case. • New-line characters are ignored in SQL, so a command may be … Read more
There are three groups of commands in SQL: 1. Data Definition 2. Data Manipulation and 3. Transaction Control
Structured Query Language, commonly abbreviated to SQL and pronounced as “sequel”, is not a conventional computer programming language in the normal sense of the phrase. It allows users to access data in relational database management systems. SQL is about data and results, each SQL statement returns a result, whether that result be a query, an … Read more
Once entities and relationships have been identified and defined, the first draft of the entity relationship diagram can be created. This post introduces the ER diagram by demonstrating how to diagram binary relationships. Recursive relationships are also shown. Binary Relationships Figure 1 shows examples of how to diagram one-to-one, one-to-many, and many-to- many relationships. Figure … Read more
The data model is one part of the conceptual design process. The other is the function model. The data model focuses on what data should be stored in the database while the function model deals with how the data is processed. To put this in the context of the relational database, the data model is … Read more
The Entity-Relationship (ER) model was originally proposed by Peter in 1976 as a way to unify the network and relational database views. Simply stated the ER model is a conceptual data model that views the real world as entities and relationships. A basic component of the model is the Entity-Relationship diagram which is used to … Read more
Database design is defined as: “design the logical and physical structure of one or more databases to accommodate the information needs of the users in an organization for a defined set of applications”. The design process roughly follows five steps: 1. Planning and analysis 2. Conceptual design 3. Logical design 4. Physical design 5. Implementation … Read more