Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Example of WHEN or THEN Constraints
A concrete example showing how SQL supports WHEN/THEN constraints
CREATE TABLE SAL_HISTORY (EmpNo CHAR (6),
Salary INTEGER NOT NULL,
From DATE
To DATE
PERIOD FOR During (From, To),
PRIMARY KEY (EmpNo, During WITHOUT OVERLAPS)
) ;
The PERIOD FOR specification states that the From and To values in each row denote a time interval (called a period because SQL uses the term "interval" for something else). The From values are treated as closed bounds, the To values as open bounds, so a given row in SAL_HISTORY indicates that an employee was paid a certain salary from the given From date up to but not including the given To date. The specification implies the column constraint NOT NULL NOT DEFERRABLE ENFORCED for each of columns From and To. During WITHOUT OVERLAPS, which, if required, must appear as the last element of the key, specifies that if the same EmpNo value appears in two distinct rows of SAL_HISTORY, then the From and To values in those rows must denote During periods that do not overlap (have no date in common).
Procedural Constraint Enforcement (Triggers) SQL has an alternative method of addressing database integrity, involving event-driven procedural code. The special procedures th
3CX PBX sync Windows Service Project Description: !! You require access to a commercial version of the 3CX PBX system in order to be able to program the API !! !! You requ
Benefit of the dynamic SQL: This part shows you how to take full benefit of the dynamic SQL and how to keep away from some of the common pitfalls. Passing the Names of Sc
Special cases of projection This section describes the identity projection, r {ALL BUT}, and the projection on no attributes, r { }, which yields TABLE_DUM when r is empty, ot
Rollback Behavior When a FORALL statement fails, the database changes are rolled back to an implicit savepoint marked before each of the SQL statement execution. The Changes t
Usefulness of Data Type In SQL, as in most computer languages, a type can be used for constraining the values that are permitted to be used for some purpose. In particular, i
what is the use of declare keyword
Need Database Development with Analysis Tools Project Description: I want a database for large governmental and private data sets on one country that can be simply extended t
Semidifference via NOT IN and a subquery SELECT StudentId FROM IS_CALLED WHERE Name = 'Devinder' AND StudentId NOT IN (SELECT StudentId FROM IS_ENROLLED_ON WHER
Parameter and Keyword Description: dynamic_string: This is a string variable, literal, or expression which represents a SQL statement or the PL/SQL block. define_vari
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd