в 13:46, 26 мая 2010

2010-05-26T13:46:16Z

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2010-05-26T10:23:20Z

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== A SELECT statement that retrieves rows with null values==



<source lang="sql">
5>
6> create table Billings (
7> BankerID INTEGER,
8> BillingNumber INTEGER,
9> BillingDate datetime,
10> BillingTotal INTEGER,
11> TermsID INTEGER,
12> BillingDueDate datetime ,
13> PaymentTotal INTEGER,
14> CreditTotal INTEGER
15>
16> );
17> GO
1>
2> INSERT INTO Billings VALUES (1, 1, "2005-01-22", 165, 1,"2005-04-22",123,321);
3> GO
(1 rows affected)
1> INSERT INTO Billings VALUES (2, 2, "2001-02-21", 165, 1,"2002-02-22",123,321);
2> GO
(1 rows affected)
1> INSERT INTO Billings VALUES (3, 3, "2003-05-02", 165, 1,"2005-04-12",123,321);
2> GO
(1 rows affected)
1> INSERT INTO Billings VALUES (4, 4, "1999-03-12", 165, 1,"2005-04-18",123,321);
2> GO
(1 rows affected)
1> INSERT INTO Billings VALUES (5, 5, "2000-04-23", 165, 1,"2005-04-17",123,321);
2> GO
(1 rows affected)
1> INSERT INTO Billings VALUES (6, 6, "2001-06-14", 165, 1,"2005-04-18",123,321);
2> GO
(1 rows affected)
1> INSERT INTO Billings VALUES (7, 7, "2002-07-15", 165, 1,"2005-04-19",123,321);
2> GO
(1 rows affected)
1> INSERT INTO Billings VALUES (8, 8, "2003-08-16", 165, 1,"2005-04-20",123,321);
2> GO
(1 rows affected)
1> INSERT INTO Billings VALUES (9, 9, "2004-09-17", 165, 1,"2005-04-21",123,321);
2> GO
(1 rows affected)
1> INSERT INTO Billings VALUES (0, 0, "2005-10-18", 165, 1,"2005-04-22",123,321);
2> GO
(1 rows affected)
1>
2>
3> SELECT *
4> FROM Billings
5> WHERE BillingTotal IS NULL
6> GO
BankerID BillingNumber BillingDate BillingTotal TermsID BillingDueDate PaymentTotal CreditTotal
----------- ------------- ----------------------- ------------ ----------- ----------------------- ------------ -----------
(0 rows affected)
1>
2> drop table Billings;
3> GO
1></source>

== IS NULL and = NULL==



<source lang="sql">
4>
5> CREATE TABLE titleauthor(
6> au_id varchar(20),
7> title_id varchar(20),
8> au_ord tinyint NULL,
9> royaltyper int NULL
10> )
11> GO
1>
2> insert titleauthor values(null, "2", 1, 60)
3> insert titleauthor values("2", "3", 1, 100)
4> insert titleauthor values("3", "4", 1, 100)
5> insert titleauthor values("4", "5", 1, 100)
6> insert titleauthor values("5", "6", 1, 100)
7> insert titleauthor values("6", "7", 2, 40)
8> insert titleauthor values("7", "8", 1, 100)
9> insert titleauthor values("8", "9", 1, 100)
10> GO
(1 rows affected)
(1 rows affected)
(1 rows affected)
(1 rows affected)
(1 rows affected)
(1 rows affected)
(1 rows affected)
(1 rows affected)
1>
2> select * from titleauthor where au_id is null;
3> GO
au_id title_id au_ord royaltyper
-------------------- -------------------- ------ -----------
NULL 2 1 60
(1 rows affected)
1> select * from titleauthor where au_id = null;
2> GO
au_id title_id au_ord royaltyper
-------------------- -------------------- ------ -----------
(0 rows affected)</source>

== The syntax of the WHERE clause with the IS NULL clause==



<source lang="sql">
WHERE expression IS [NOT] NULL
The contents of the NullSample table
SELECT * FROM NullSample</source>

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в 13:46, 26 мая 2010

Admin: 1 версия