Create, alter, drop
In this category of SQL, we affect the structure of the database, not the content. The first example shows a create sentence, where you typically make a new table. Here's a simple example:
CREATE TABLE player (
p_name VARCHAR(50) NOT NULL PRIMARY KEY,
password VARCHAR(50) NOT NULL
)
Create the table "player", with a column called "p_name" (50 characters at most, and there has to be something, and this is the primary key of the table), and a column called "password" (50 characters at most, and there has to be something).Sometimes there's the need to change in the already existing tables - e.g. create a new column. Below there's a simple example.
ALTER TABLE player
ADD gender VARCHAR(10)
Change the table "player", by adding a new column, called "gender" (10 characters at most).Finally there can be the need to delete an entire table. Here's an example.
DROP TABLE playerDelete the table "player".
Concept last updated: 06/05 2004.
Relations
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Other sources
- InterBase tutorial mm. (obl.) - s.10-11, s.14-16, s.19-22, s.26-30