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Explicitly specifying the join condition - SQL
SELECT *
FROM IS_CALLED JOIN IS_ENROLLED_ON
ON ( IS_CALLED.StudentId = IS_ENROLLED_ON.StudentId )
Now, the key word JOIN in all of the foregoing examples can be harmlessly preceded by the word INNER. SQL also supports what are called "outer joins". The outer join of t1 and t2 contains all the rows of the inner join and possibly some more if either operand has rows which fail to participate in the inner join. Such a row might participate in the outer join, accompanied by NULL for each column of the other operand. The key words LEFT, RIGHT, and FULL, each optionally followed by OUTER, are used to specify whether unmatched rows of the first (left) operand, the second (right) operand, or both operands, respectively, are to appear in the result. Example shows an SQL outer join. A single row for student S5 appears in the result, with NULL in place of a value for CourseId.
Short-Circuit Evaluation When computing a logical expression, the PL/SQL uses short-circuit evaluation. That is, the PL/SQL stops computing the expression as soon as the result
Referencing Records Unlike the elements in a collection, that are accessed using subscripts, the fields in a record are accessed by name. To reference an individual field, you
Parameter and Keyword Description: record_type_name: This identifies the user-defined type specifier that is used in the subsequent declarations of the records. NOT N
Aggregate Operators SQL Supports all of the aggregate operators mentioned in the theory book and many more besides. The syntax, however, involves an unusual trick that SQL cal
Important Distinctions The list of important distinctions are given below: Value versus variable Syntax versus semantics Variable versus variable reference
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Example of DELETE - SQL As with UPDATE, a FOR PORTION OF clause can be specified if the target table has a defined period name, as illustrated in Example. Example: Deleting
Nested Tables versus Index-by Tables The Index-by tables and nested tables are just similar. For e.g. They have similar structure and their individual elements are accessed in
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