Cheatsheet

To create a table

CREATE table table_name(column_name_1 data_type constraint, column_name_2 data_type constraint)

Warning

Add primary key after the colum_name if that column is primary.

To select from a table

All columns

select * from table_name

Specific column

select column_name(s) from table_name

To insert into table

insert into table_name values(all_values_seprated_by_comma)

Warning

Note: char and varchar must be enclosed with single quotes(')

Creating keys

Primary key

Add the primary key keyword after the column_name.

Tip

primary key declaration on an attribute ensures that the attribute is not null

Composite primary key

Add the primary key (column_name_1, column_name_2, ....) at the end before the closing parentheses ) while creating the table.

Foreign key

Add the foreign key (column_name) references parent_table(parent_column)at the end before the closing parentheses ) while creating the table.

Deleting rows

delete from table_name where delete_condition(s)

Alter

Adding an attribute

alter table table_name add attribute_name data_type

Deleting an attribute

alter table table_name drop attribute_name

Important Points to Note

• delete: Delete row(s) from the table. But schema is not lost
• drop: Entire table is deleted along with schema.
• truncate: Deletes the table along with schema, but the schema is regenerated.