DDD - Implementation
No description yet. This curated deck is ready for daily study.
Card preview (21)
How are tables linked in a relational database
tables are linked by matching the foreign key from one table to the primary key in a related table
what does referential integrity mean
that all of the foreign keys in a table must link to a primary key in a related table
What does the SELECT statement
selects data from a database
what does the asterisk symbol do
select all of the fields in the table
The FROM command is used to
specify which tables to select data from
what does the order by statement
sorts the results of an SQL query in ascending or descending order
what is ascending order
A-Z, 1-10
what is descending order
Z-A, 10-1
<
less than
>
greater than
=
equal
when will <,>, = operators can be used
within the WHERE clause to refine SQL queries
When can the OR and AND operators can be used
with the WHERE clause to refine SQL queries
what is the INSERT INTO statement used for
to insert a record into a table
syntax for insert
INSERT INTO table VALUES (values to be inserted);
what is the UPDATE staement used for
to update a record in atable
syntax for update
UPDATE table SET column = value WHERE criteria;
What is the DELETE statement used for
to delete a record from a table
syntax for delete
DELETE FROM table WHERE criteria;
what is an equi-join
used to join matching columns of related tables
syntax for equi-joins
SELECT fields FROM table_1, table_2 WHERE table_1.column_name= table_2.column_name