Here is a post for my students who are beginning there work in data analytics.
SQL (Structured Query Language) is a programming language designed to work with a relational database management system (RDBMS).
Key points to remember about SQL:
- SQL is a query tool. Structured query language is a programming language. We can use development environments (like BigQuery) to help create programs, but SQL programs are written as text in specified formats. It is used to find data contained in databases; when we find this data, we call it a “query.” SQL is used for structured data tables comprising rows and columns.
- The original program was developed by IBM, and since then, there have been many different languages based on SQL. The most popular are PostgreSQL, SQLite, MySQL, and SQL Server.
- These languages all have very similar syntax. In general, it is:
SELECT
FROM
WHERE
The SELECT is follows by the names of the columns you want in the query.
The FROM is followed by the table from which the data will be selected.
The WHERE is followed by data we want to filter for. For example, the query
SELECT first_name, last name
FROM employees
WHERE department = 'IT';Will return the first name and last name of the employees who work in the IT department.