Using Variables in T-SQL Variables are needed to set values DECLARE @variablename data_type Must start with the character @ Vari...

Examining Totals with Counts SELECT COUNT(*) FROM Incidents The above sql statments returns the total number of rows in the Incidents table. Count w...

Exploring Data With Aggregation Reviewing summarized values for each column is a common first step in analyzing data If the data exists in a database, fastest way to aggreg...

Implementing relationships with Foreign Keys A Foreign Key (FK) points to the Primary key (PK) of another table. Domain of FK must be equal to the domain of PK Each v...

What is a Key? Attribute(s) that idenfity a record uniquely As long as attributes can be removed: superkey If no more attributes can be removed: minimal superky or ke...

Integrity Constraints Attribute Constraints, e.g data types on columns Key Constraints, e.g primary keys Referential Integrity Constraints, enforced through foreign k...

Using information schema SELECT table_schema, table_name FROM information_schema.tables; Taking the look at the columns of a ...

CRUD OPERATION CREATE Databases, Tables or Views Users, prermissions and security groups READ Example: SELEC...

PRIMARY KEYS: A primary key is used to ensure data in the specific column is unique. It is a column cannot have NULL values. It is either an existing table column or a column that is speci...

SUM It is used to calculate the total amount of a column. Example: SELECT SUM(affected_customers) AS total_affec...