Tools for Information Literacy | Week ⑭ 
Structured Query Language

What is SQL?

Structured Query Language is the standard means of manipulating and querying data in relational databases.

Just as HTML ( Hypertext Markup Language) is a language that uses elements, attributes, and values (markup) to construct and link (hypertext) documents for easy access and display

So SQL ( Structured Query Language) is a language that uses a particular syntax in order to retrieve needed items from a relational database.

What Can SQL do?

SQL ...

• can execute queries against a database
• can retrieve data from a database
• can insert records in a database
• can update records in a database
• can delete records from a database
• can create new databases
• can create new tables in a database
• can create stored procedures in a database
• can create views in a database
• can set permissions on tables, procedures, and views

SQL is a Standard - BUT....

although SQL is an ANSI/ISO standard, there are different versions of the SQL language.

However, to be compliant with the ANSI standard, they all support at least the major commands (such as SELECT, UPDATE, DELETE, INSERT, WHERE) in a similar manner.

Before SQL comes into play ...

One will have designed multiple entity classes and populated them with records to creat entity sets

Then, SQL may be used to retrieve needed data from the entity sets

We have used SQL terminology in describing Excel filters, but now we will try to work with SQL itself

We may use the W3Schools SQL tutorial to get a sense of SQL and how it works.