Preferred language for data management and manipulation.
T-SQL is a dialect of standard SQL. SQL is a standard of both the International Organization for Standards (ISO) and the American National Standards Institute (ANSI).
Common Table Expression (CTE)
Standard SQL is based on the relational model, which is a mathematical model for data management and manipulation.
A common misconception is that the name “relational” has to do with relationships between tables (that is, foreign keys). Actually, the true source for the model’s name is the mathematical concept relation.
A relation has a heading and a body. The heading is a set of attributes (what SQL attempts to represent with columns), each of a given type. An attribute is identified by name and type name. The body is a set of tuples (what SQL attempts to represent with rows). Each tuple’s heading is the heading of the relation. Each value of each tuple’s attribute is of its respective type.
T-SQL stem from the relational model’s core foundations—set theory and predicate logic.
the heading of a relation is a set of attributes, and the body a set of tuples.
By a “set” we mean any collection M into a whole of definite, distinct objects m (which are called the “elements” of M) of our perception or of our thought.