Term
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Definition
| A sequence or list of values. Also used to refer to a row. |
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Term
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Definition
| A relation between n-values. |
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Term
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Definition
| Refers to a column of a table. |
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Term
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Definition
| Refers to that specific instance of a table (or relation, dur). |
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Definition
| Set permitted values for attributes, such as all possible values for a salary attribute. |
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Term
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Definition
| It is required that all domains of r be atomic, meaning elements of a domain are indivisible. |
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Term
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Definition
| Logical design of a database. |
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Definition
| Is a special value that signifies that a value is unknown or DNE. |
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Term
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Definition
| A set of one or more attributes that, taken collectively, allow us to identify uniquely a tuple on the relationship. |
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Term
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Definition
| A super-key that contains extraneous attributes. If K is a super-key, then so is any super-set of K. |
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Term
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Definition
| A set containing all the other elements of another set. |
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Term
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Definition
| A key (usually a super-key) that is assigned by the database designers the principle means of identifying tuples within a relation. |
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Term
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Definition
| A primary-key that is referencing a primary-key from another relation. Say, r1 may include a primary key from r2. |
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Term
| Referenc(ing) Relation / Referenc(ed) Relation |
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Definition
| r1 from Foreign-key / r2 from Foreign-key |
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Term
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Definition
| A database schema with primary- and foreign-keys shown. |
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Term
| Referential Integrity Constraint |
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Definition
| Requires that the values appearing in specified attributes of any tuple in the referencing relation (r1) also appear in specified attributes of at least one tuple in the referenced relation (r2). |
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Term
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Definition
| A language in which a user requests information from the database. |
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Term
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Definition
| The user instructs the system to perform a sequence of operations on the database to computer the desired result. |
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Term
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Definition
| The user describes the desired information without giving a specific procedure for obtaining that information. |
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Term
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Definition
| The combining of two relations by merging pairs of tuples, one from each relation, into a single tuple. |
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Term
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Definition
| Returns rows of the input relation that satisfy the predicate. Selection(salary>=65k^(instructor)). |
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Term
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Definition
| Output specificed attributes from all rows of the input relation. Remove duplicate tuples from the output. Projection(ID,Salary^(instructor)) |
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Term
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Definition
| Output pairs of rows from the two input relations that have the same value on all attributes that have the same name. |
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Term
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Definition
| Output all pairs from the two input relations that have the sane value on all attributes that have the same name. Instructor X department. |
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Term
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Definition
| Output the union of tuples from the two input relations. Projection(name^(instructor)) Union Projection(name^(student)). |
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Term
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Definition
| Used to combine like rows from two queries. It returns rows that are in common between both results. To use the INTERSECT operator, both queries must return the same number of columns and those columns must be of compatible data types. |
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Term
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Definition
| Outputs the a relation where if A-B then the output would be none of B and any relation of B found in A is removed. (Something like that). |
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