A SELECT statement that uses the COALESCE function : COALESCE « Data Convert Functions « SQL Server / T-SQL Tutorial






  1. SQL Server / T-SQL Tutorial
  2. Data Convert Functions
  3. COALESCE
7>
8> create table Billings (
9>     BankerID           INTEGER,
10>     BillingNumber      INTEGER,
11>     BillingDate        datetime,
12>     BillingTotal       INTEGER,
13>     TermsID            INTEGER,
14>     BillingDueDate     datetime ,
15>     PaymentTotal       INTEGER,
16>     CreditTotal        INTEGER
17>
18> );
19> 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> SELECT BillingDate,
3>     COALESCE(BillingDate, '1900-01-01') AS NewDate
4> FROM Billings
5> GO
BillingDate             NewDate
----------------------- -----------------------
2005-01-22 00:00:00.000 2005-01-22 00:00:00.000
2001-02-21 00:00:00.000 2001-02-21 00:00:00.000
2003-05-02 00:00:00.000 2003-05-02 00:00:00.000
1999-03-12 00:00:00.000 1999-03-12 00:00:00.000
2000-04-23 00:00:00.000 2000-04-23 00:00:00.000
2001-06-14 00:00:00.000 2001-06-14 00:00:00.000
2002-07-15 00:00:00.000 2002-07-15 00:00:00.000
2003-08-16 00:00:00.000 2003-08-16 00:00:00.000
2004-09-17 00:00:00.000 2004-09-17 00:00:00.000
2005-10-18 00:00:00.000 2005-10-18 00:00:00.000

(10 rows affected)
1> drop table Billings;
2> GO
1>








13.2.COALESCE
13.2.1.COALESCE is equivalent to a CASE expression that returns the first NOT NULL expression in a list of expressions.
13.2.2.Returning the First Non NULL Value in a List of Expressions
13.2.3.COALESCE() saves quite a lot of IF or CASE decision logic.
13.2.4.A SELECT statement that uses the COALESCE function
13.2.5.A SELECT statement that substitutes a different data type