SQL Server/T-SQL Tutorial/System Settings/ERROR

A stored procedure that uses the @@ERROR system function

7> create table Billings (
8>     BankerID           INTEGER,
9>     BillingNumber      INTEGER,
10>     BillingDate        datetime,
11>     BillingTotal       INTEGER,
12>     TermsID            INTEGER,
13>     BillingDueDate     datetime ,
14>     PaymentTotal       INTEGER,
15>     CreditTotal        INTEGER
16>
17> );
18> 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> CREATE PROC spInsertBilling
4>        @BankerID    int,           @BillingNumber  varchar(50),
5>        @BillingDate smalldatetime, @BillingTotal   money,
6>        @TermsID     int,           @BillingDueDate smalldatetime
7> AS
8> DECLARE @ErrorVar int
9> INSERT Billings (BankerID)
10> VALUES (@BankerID)
11> SET @ErrorVar = @@ERROR
12> IF @ErrorVar <> 0
13>     BEGIN
14>         IF @ErrorVar = 547
15>             PRINT "Not a valid BankerID!"
16>         ELSE
17>             PRINT "An unknown error occurred."
18>         RETURN @ErrorVar
19>     END
20> GO
1>
2>
3> drop PROC spInsertBilling;
4> GO
1>
2>
3> drop table Billings;
4> GO

Attempt to Capture @@IDENTITY, @@ROWCOUNT, and @@ERROR

4> CREATE TABLE T1(
5>   pk_col    int NOT NULL PRIMARY KEY CHECK (pk_col > 0),
6>   ident_col int NOT NULL IDENTITY (1,1)
7> )
8>
9> DECLARE
10>   @myerror    AS int
11> INSERT INTO T1 VALUES(0) -- violate the check constraint
12> SET @myerror = @@ERROR
13> IF @myerror = 2627
14>   PRINT "PRIMARY KEY constraint violation"
15> ELSE IF @myerror = 547
16>   PRINT "CHECK constraint violation"
17> GO
Msg 547, Level 16, State 1, Server J\SQLEXPRESS, Line 11
The INSERT statement conflicted with the CHECK constraint "CK__T1__pk_col__3C54ED00". The conflict occurred in database "master", table "dbo.T1", column "pk_col".
The statement has been terminated.
CHECK constraint violation
1>
2> --Attempt to Capture @@IDENTITY, @@ROWCOUNT, and @@ERROR
3> DECLARE
4>   @myerror    AS int,
5>   @myrowcount AS int,
6>   @myidentity AS int
7> INSERT INTO T1 VALUES(10) -- PK violation
8> SELECT @myidentity = @@IDENTITY,
9>        @myrowcount = @@ROWCOUNT,
10>        @myerror    = @@ERROR
11> PRINT "@myidentity: " + CAST(@myidentity AS varchar)
12> PRINT "@myrowcount: " + CAST(@myrowcount AS varchar)
13> PRINT "@myerror   : " + CAST(@myerror AS varchar)
14> GO
(1 rows affected)
(1 rows affected)
@myidentity: 2
(1 rows affected)
@myrowcount: 1
(1 rows affected)
@myerror   : 0
1> --Output of Successful Attempt to Capture @@IDENTITY, @@ROWCOUNT, and @@ERROR
2>
3> drop table T1;
4> GO

Check the @@ERROR with if statement

11> create table Billings (
12>     BankerID           INTEGER,
13>     BillingNumber      INTEGER,
14>     BillingDate        datetime,
15>     BillingTotal       INTEGER,
16>     TermsID            INTEGER,
17>     BillingDueDate     datetime ,
18>     PaymentTotal       INTEGER,
19>     CreditTotal        INTEGER
20>
21> );
22> 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> CREATE PROC spInsertBilling
4>        @BankerID    int,           @BillingNumber  varchar(50),
5>        @BillingDate smalldatetime, @BillingTotal   money,
6>        @TermsID     int,           @BillingDueDate smalldatetime
7> AS
8> DECLARE @ErrorVar int
9> INSERT Billings (BankerID)
10> VALUES (@BankerID)
11> SET @ErrorVar = @@ERROR
12> IF @ErrorVar <> 0
13>     BEGIN
14>         IF @ErrorVar = 547
15>             PRINT "Not a valid BankerID!"
16>         ELSE
17>             PRINT "An unknown error occurred."
18>         RETURN @ErrorVar
19>     END
20> GO
1>
2> DECLARE @ReturnVar int
3> EXEC @ReturnVar = spInsertBilling
4>      799,"ZXK-799","2002-07-01",299.95,1,"2001-08-01"
5> PRINT "Return code was: " + CONVERT(varchar,@ReturnVar)
6> GO
(1 rows affected)
(1 rows affected)
Return code was: 0
1>
2>
3> drop PROC spInsertBilling;
4> GO
1>
2>
3> drop table Billings;
4> GO
1>

connection-level exception

6> CREATE PROCEDURE ConversionException
7> AS
8> BEGIN
9>     SELECT CONVERT(INT, "abc")
10> END
11> GO
1>
2>
3> EXEC ConversionException
4> PRINT "This will NOT print!"
5> GO
Msg 245, Level 16, State 1, Server J\SQLEXPRESS, Procedure ConversionException, Line 9
Conversion failed when converting the varchar value "abc" to data type int.
1>
2> drop PROCEDURE ConversionException;
3> GO

@@error is

After each Transact-SQL statement, the server sets the value of this variable to an integer value:
0 If the statement was successful
Error number If the statement has failed

@@ERROR reset

6> SELECT 1/0 AS DivideByZero
7> IF @@ERROR <> 0
8>     SELECT @@ERROR AS ErrorNumber
9> GO
Msg 8134, Level 16, State 1, Server J\SQLEXPRESS, Line 6
Divide by zero error encountered.

Observing line numbers in exceptions

6> SELECT 1
7> GO
-----------
          1
(1 rows affected)
1> SELECT 2
2> GO
-----------
          2
(1 rows affected)
1> SELECT 1/0
2> GO
Msg 8134, Level 16, State 1, Server J\SQLEXPRESS, Line 1
Divide by zero error encountered.
1>
2>

Parse exception

3> SELECTxzy FROM SomeTable
4> PRINT "This will NOT print!"
5> GO
Msg 156, Level 15, State 1, Server J\SQLEXPRESS, Line 3
Incorrect syntax near the keyword "FROM".
1>

== SELECT/td>

3> SELECT 5 / 0
4>
5> SELECT @@ERROR
6> GO
Msg 8134, Level 16, State 1, Server J\SQLEXPRESS, Line 3
Divide by zero error encountered.
-----------
       8134
(1 rows affected)

SELECT * FROM master.dbo.sysmessages WHERE error = @@ERROR

4> SELECT 5 / 0
5> SELECT * FROM master.dbo.sysmessages WHERE error = @@ERROR
6> GO
Msg 8134, Level 16, State 1, Server J\SQLEXPRESS, Line 4
Divide by zero error encountered.
error       severity dlevel description
                                                                                    msglangid
----------- -------- ------ ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------- ---------
       8134       16      0 Divide by zero error encountered.
                                                                                         1033
(1 rows affected)

Using @@ERROR

7> SELECT 1/0 AS DivideByZero
8> SELECT @@ERROR AS ErrorNumber
9> GO
Msg 8134, Level 16, State 1, Server J\SQLEXPRESS, Line 7
Divide by zero error encountered.