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What is a null-capable field?
A null-capable field has • Its value, 3.2, 'Jack Sprat' etc. • An associated value that says whether it is null or not, called a "null indicator" If the null indicator is "on", then the value in the field is meaningless.

What if a null indicator is 'on'?
If the null indicator is "on", then the value in the field is meaningless. For example, if a customer does not have any orders, the due- date for the orders is meaningless, so it may be useful to define the "duedate" field as null-capable, to avoid trying to use the date's value when it has no meaning. © 2017 IBM Corporation Cognitive Systems 5

Does dsppfm show a null-capable field?
The "field" part of a null-capable field always has a value, even if the null-indicator is on. DSPPFM shows the values of the "field" part of a field. It does not have any way to show the null-indicators. • For the record 1, DUEDATE is null. The field value is '0001- 01-01'. • For the record 2, PRVBAL is null. The field value is 0000.00.

Can a column be declared not null?
By default, must be aware of possible NULLs for all columns. Recall, however, a column can be declared NOT NULL. Unlike WHERE clause, CHECK constraints and FOREIGN KEY constraints ensure that no tuple returns false. Data from Table1 appear in result only if matching row exists in Table2.

[PDF File]NULL VALUES - Cheriton School of Computer Science
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NULL value in budget •Similarly for set operations: all NULLs treated as if a single value • e.g., {(A,B,NULL),(A,B,C)} ∩ {(A,B,D),(A,B,NULL)} = {(A,B,NULL)} (SELECT genre, budget FROM Film WHERE gross > 15000000) UNION (SELECT genre, budget FROM Film WHERE year > 2000) •Similarly, too, for duplicate elimination with SELECT DISTINCT

[PDF File]DATABASE MANAGEMENT LAB PRACTICAL - Bharath Univ
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To Select NULL values: We can use the SELECT statement to select the ‘null’ values also. For retrieving roes where some of the columns have been defined as NULLs there is a special comparison operator of the form IS [NOT]NULL. Syntax: SELECT column name FROM table_name WHERE Column name IS NULL; 11. Select using AND, OR, NOT:

[PDF File]Range and Null Space
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suppose null ,and represents measurement of is undetectable from sensors — get zero sensor readings and are indistinguishable from sensors: null characterizes ambiguity in from measurement alternatively, if represents output resulting from input is an input with no result and have same result null characterizes freedom of input choice for ...

[PDF File]SQL Week 2: Part II SQL I – Data Definition Language
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FirstName char(20) not null, Surname char(20) not null, Dept char(15), Salary numeric(9) default 0, City char(15), primary key(RegNo), foreign key(Dept) references Department(DeptName) on delete set null on update cascade, unique(FirstName,Surname)) How else could we have identified the primary key?

[PDF File]Working with null-capable fields - IBM
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CREATE TABLE MYLIB/TESTNULL (NUM_ORDERS DECIMAL (7, 0) NOT NULL WITH DEFAULT, DUE_DATE DATE) • The NUM_ORDERS field is defined with "NOT NULL WITH DEFAULT", so it is not null capable • The DUE_DATE field does not have "NOT NULL", so it is null-capable In DDS, you use the ALWNULL keyword A R REC A NUM_ORDERS 7P 0 A DUE_DATE L DATFMT(*ISO) ALWNULL

[PDF File]Intermediate SQL - Database System Concepts
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Practice Exercises. 4.1 Write the following queries in SQL: Display a list of all instructors, showing their ID, name, and the num-ber of sections that they have taught. Make sure to show the number of sections as 0 for instructors who have not taught any section. Your query should use an outerjoin, and should not use scalar subqueries.

And select null seteq null is null irgd