PL/SQL User Defined types - Record and Table
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You also learn how to reference and manipulate index by binary_integer count collections as whole objects. Think of the key and rows as the index and elements of a one-dimensional array. Each index by binary_integer count has a unique index number that determines its position in the ordered collection.
This characteristic, called sparsityallows the use of meaningful index numbers. For example, you can use a series of employee numbers such as, They can index by binary_integer count columns or rows of Oracle data, and they can be passed as parameters.
That allows you to pass host arrays to stored functions and procedures. For example, index by binary_integer count following declaration is illegal: As the example below shows, the index number can be negative. For example, the following assignment is legal: Until an element is assigned a value, it does not exist. That is, the following syntax is illegal: COUNT gives you the answer.
FOR i IN NEXT n returns the index number that succeeds index n. Likewise, if n has no successor, NEXT n returns a null. For example, the following statement assigns index n to itself: Recall that index numbers need not be consecutive. Consider the following examples: As you delete elements, memory is freed page by page.
If you try, you get a compilation error, as the following example shows: Or, you can select an entire row into a record element. Instead of the FETCH statement, you can use a cursor FOR loop, which implicitly declares its loop index as a record, opens the cursor associated with a given query, repeatedly fetches rows of values into fields in the record, then closes the cursor.
Given the array subscript range m. For example, if the array subscript range is The corresponding actual parameters are host arrays. By default, when binding the host array, the Oracle Precompilers use its declared dimension. This saves time and reduces network traffic. But, you cannot specify the datatypes of fields in the record or declare fields of your own. Records contain uniquely named fields, which can have different datatypes. Suppose you have various data about an employee such as name, salary, and hire date.
These items are dissimilar in type but logically related. A record containing a field for each item lets you treat the data as a logical unit. Each field index by binary_integer count a unique name and specific datatype. When you declare a record of type TimeTypits three fields assume an initial value of zero. That is, a record can be the component of another record, as the following example shows: That allows the function to return a user-defined record of the same type.
Like scalar variables, user-defined records can be declared as the formal parameters of procedures and functions. You can assign the value of an expression to a specific field using the following syntax: This can be done in two ways. First, you can assign one record to another if index by binary_integer count have the same datatype, as the following example shows: The column names must appear in the same order as the fields in your record.
So, the following statement is illegal: Therefore, the following syntax is illegal: For instance, the following IF conditions are illegal: Such assignments are allowed even if the parent records have different datatypes. END; Function Results When calling a function that returns a user-defined record, you use the following syntax to reference fields in the record: The index by binary_integer count is easy to manipulate because you can index by binary_integer count to the collection as a whole.
In the following example, you collect accounting figures from the database tables assets and liabilitiesthen use ratio analysis to compare the performance of two subsidiary companies: