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'