What does a SQL statement look like?
- SQL statements are somewhat like simple English sentences.
- Keywords include SELECT, UPDATE, WHERE, ORDER BY, etc.
- ANSI Standard SQL is the lingua franca for relational databases.
- By the way, the syntax of a language describes the language elements.
The SQL Syntax
SQL was designed to be entered on a console and results would display back to a screen. Today, SQL is mostly used by programmers who use SQL inside their language to build applications that access data in a database.
Four fundamental operations that apply to any database are:
- SELECT -- Read the data
- INSERT -- Insert new data
- UPDATE -- Update existing data
- DELETE -- Remove data
Collectively these are referred to as CRUD (Create, Read, Update, Delete).
The general form for each of these 4 operations in SQL is presented next.
The SQL SELECT general form
SELECT column-names FROM table-name WHERE condition ORDER BY sort-order
SELECT FirstName, LastName, City, Country FROM Customer WHERE City = 'Paris' ORDER BY LastName
The SQL INSERT general form
INSERT table-name (column-names) VALUES (column-values)
INSERT Supplier (Name, ContactName, City, Country) VALUES ('Oxford Trading', 'Ian Smith', 'Oxford', 'UK')
The SQL UPDATE general form
UPDATE table-name SET column-name = column-value WHERE condition
UPDATE OrderItem SET Quantity = 2 WHERE Id = 388
The SQL DELETE general form
DELETE table-name WHERE condition
DELETE Customer WHERE Email = 'firstname.lastname@example.org'