Schemas

A schema is the definition of the table: the names of the tables, the names of the columns, the types of data in each column. It also includes some other database elements. (e.g. index)

Usually each project has its own schema and usually there is no relation between data in one schema and another schema.

Each databse usually can hold several schemas.

So you can have a database server that holds multiple schemas.

Though SQ is usually case-insensitive, some people prefer to write every SQL word in upper-case letters and every user-specified field in lower-case. We’ll use this style.

A number of the keywords in the SQL language:

• CREATE
• ALTER
• INSERT INTO
• SELECT
• UPDATE
• DELETE
• TABLE
• INDEX
• FROM
• WHERE