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Understanding Nested TablesWithin the database, the nested tables can be considered as one-column database tables. The Oracle stores the rows of a nested table in no specific order. But, when you retrieve the nested table into the PL/SQL variable, the rows are given consecutive subscripts starting at 1. That provides you array-like access to the individual rows.Within PL/SQL, the nested tables are like one-dimensional arrays. Though, nested tables differ from arrays in two significant ways. Firstly, the arrays have a fixed upper bound, but nested tables are unbounded .Therefore, the size of a nested table can increase dynamically.
Figure: Array versus Nested TableSecondly, the arrays should be dense (having consecutive subscripts). Therefore, you cannot delete individual elements from an array. Initially, the nested tables are dense, but they can be sparse (having nonconsecutive subscripts). And hence, you can delete elements from a nested table using the built-in procedure DELETE. That might leave gaps in the index, but the built-in function NEXT iterate over any series of subscripts.
Avoid the NOT NULL Constraint In the PL/SQL, using the NOT NULL constraint incur a performance cost. Consider the illustration as shown below: PROCEDURE calc_m IS m NUMB
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Implicit Rollbacks Before execute the INSERT, UPDATE, or DELETE statement, the Oracle marks an implicit savepoint . When the statement fails, the Oracle rolls back to the save
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Keyword and Parameter Description: label_name: This is an undeclared identifier which labels an executable statement or the PL/SQL block. You can use a GOTO statement to
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