Chapter 8 Transact-SQL Program Design

8.1_ variables

8.1.1_ local variables

Declaration definition of local variables:

Declare @Variable_name Datatype[, @Variable_name Datatype]…

--举例：
declare  @s1 char(20),@s2 int

Where @Variable_name is the name of a local variable, it must start with @ and follow the SQL Server 2000 identifier and object naming convention

Assignment method:
initialize at the time of declaration:

declare  @s2 int = 20

Settings:

set @s2 = 20

8.1.2_ Global Variables

SQL Server 2000 provides a system and assign variables, users can not create global variables , also can not use the SET statement to change the value of a global variable , it starts with @@ , most of the values of global variables is to report the occurrence of SQL Server 2000 system after start Activities, usually assign the value to a local variable for processing.

8.2_ Flow control statement

Let me talk about the statement block first, and begin is used here. . . The end statement is
begin...end is the curly braces in the C language.
Secondly, the print output uses print'string'

8.2.1_IF...ELSE statement

IF (SELECT ContractVolume FROM Contract WHERE ContractID=’101’) >10000
   PRINT '该合同金额超过1万元'
ELSE
   PRINT '该合同金额不足1万元'

8.2.2_while loop statement

--打印1到10
DECLARE @i INTEGER
DECLARE @iMAX INTEGER
SET @iMAX = 10
SET @i=1
WHILE @i<=@iMAX
BEGIN
		PRINT @i
		SET @i=@i+1
END