About the basics of getting started with SQL stored procedures (Process Control) _mssql

Here we talk about the process control of the stored procedure, if else,case, while, there is no for loop, these and c,c++,c# languages are poor.

First, let's see if else uses

Copy Code code as follows:

If condition
Begin
SQL statement
End
ELSE begin
SQL statement
End

Look at a simple example

Copy Code code as follows:

DECLARE @id INT--Declaring a variable
Set @id = 5--Setting Kitchen initial value
if (@id =1)
Begin
print ' Right '
End
else if (@id =0)
Begin
print ' ERROR '
End
Else
Begin
print ' Default '
End

The result I think everybody should know, don't write out, here begin, end also can not write, but suggest write, this like C + + code {}, say a piece, write to the level clearer.

Of course, if nesting is also possible.

Two, while the use of

We're going to calculate the sum of 1 to 100.

Copy Code code as follows:

Declare @i int, @sum int
Set @i=0
Set @sum =0
While @i<=100--Start loop
Begin
Set @i=@i+1--self-adding one
Set @sum = @sum +@i
End
Print @sum
Results
-----------

Three, case multiple choice of use

Copy Code code as follows:

Declare @iret int, @var varchar (10)
Set @var = ' A '
Select @iret =
case when @var = ' A ' then 0
When @var = ' B ' then 1
When @var = ' C ' then 2
When @var = ' D ' then 3
Else-1
Print @iret

Results
-------

The above basic flow control, basically can meet our daily development needs, temporarily think of so much, which day think of other circumstances, will be appropriate to supplement.