SQL Basics (i)

1. How the data is stored (table property Operations)

1.1 questions to consider before building a table

A. Table name

B. table contains data type (CHAR (fixed-length character), VARCHAR (indefinite long character), number (numeric), date (date and time), BLOB (large data set), straight string, custom type)

C. Fields that make up the primary key

D. length of each field

E. Which fields can be null

1.2 CREATE TABLE Statement

Basic syntax:

CREATE TABLE table_name (field1 data_type [NOT NULL],  field2 data_type [NOT NULL],  field3 data_type [NOT NULL ],  field4 data_type [NOT NULL]);

1.3 ALTER TABLE Command

Basic syntax:

ALTER TABLE table_name [modify] [column column_name] [data_type] [NULL not null][restrict|cascade][drop] [constraint cons Traint_name][add]  [column] clumn definition

A. Adding attributes

SQL Basics (i)