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Aggregate AssignmentThe %ROWTYPE declaration cannot include an initialization clause. Though, there are two ways to assign values to all fields in a record at once. At First, the PL/SQL allows the aggregate assignment between the whole records if their declarations refer to the similar table or cursor. For illustration, the assignment below is legal:DECLAREdept_rec1 dept%ROWTYPE;dept_rec2 dept%ROWTYPE;CURSOR c1 IS SELECT deptno, dname, loc FROM dept;dept_rec3 c1%ROWTYPE;BEGIN...dept_rec1 := dept_rec2;However, because dept_rec2 is based on a table and dept_rec3 is based on acursor, the following assignment is illegal:dept_rec2 := dept_rec3; -- illegalSecondly, you can assign a list of column values to a record by using the SELECT or FETCH statement, as the illustration below shows. The column names should appear in the order in which they are defined by the CREATE TABLE or CREATE VIEW statement.DECLAREdept_rec dept%ROWTYPE;...BEGINSELECT deptno, dname, loc INTO dept_rec FROM deptWHERE deptno = 30;
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
Updating Variables For assignment, SQL uses the key word SET, as in SET X = X + 1 (read as "set X equal to X+1") rather than X: = X + 1 as found in many computer languages.
Define basic operators of relational algebra with an example each
PRIMARY KEY: PRIMARY KEY indicates that the table is subject to a key constraint, in this case declaring that no two rows in the table assigned to ENROLMENT can ever have the
Inner Join We have learned how to retrieve data from one table by using SELECT statement. But, as we have learned, normalized relational databases mean the data is spread betw
Declaring and Initializing Objects: An object type is once defined and installed in the schema; you can use it to declare the objects in any PL/SQL, subprogram, block or packa
Using Operator VALUE: As you may expect, the operator VALUE returns the value of an object. The VALUE takes its argument a correlation variable. For illustration, to return a
Authorisations - Privileges As relational theory is silent on the issue of authorisation, it offers nothing with which SQL's vast edifice in support of what it calls privilege
CHECK Constraints in SQL A CHECK constraint is a table constraint defined using the key word CHECK, as already illustrated in several examples in this chapter. In particular,
Attributes: Just similar to variable, an attribute is declared with a name and datatype. The name should be exclusive within the object type. The datatype can be any Oracle ty
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