T_SQL编程

/*
IF ELSE 语句 BEGIN END 相当予C语言中的{}
当语句块中只有一句的时候 可以省略 BEGIN END
while
begin
...语句块
end
PRINT 打印输出信息

*/
declare @num int
select @num=100;
WHILE @num>90
BEGIN
if @num> 80
BEGIN
PRINT 'this teacher is very successful '
END
else
BEGIN
PRINT 'this teacher is a failure'
END
set @num=@num-1
END

2. CASE WHEN THEN 的用法

SELECT * , new =CASE COLUMN WHEN ........ THEN ............ FROM TABLE 从表中增加新的一列 通过 CASE 语句