--取數值表達式的絕對值select abs(-41) 41select abs(41) 41select abs(-41.12) 41.12select abs(41.12) 41.12--弧度表達式 括號內是（1 -1）select acos(0.5) 1.0471975511966select asin(0.5) 0.523598775598299select atan(0.5) 0.463647609000806select atn2(0.5 ,1) 0.463647609000806--返回給定數的最小 最大正整數select ceiling(44.2) 45select floor(44.2) 44--返回給定角的三角余弦 給定弧度算出數值select cos(0) 1select exp(2) --e^() 7.38905609893065select power(3,2) 9--求近似值select round(44.546,2) 44.550select sign(-45) -1select sign(45) 1select sign(0) 0--隨機數 0-1之間的數select rand()--求平方根select sqrt(4) 2select square(4+5) 81--字符串函數select ascii(0) --unicode的值 48 select char(48) 0--返回字符串中指定的表達式的開始位置select charindex('abcd','a') 0 select difference('abc','acd') 3select left('abc',2) -- abselect len('abc') 3select lower('ABC') abcselect ltrim(' abc') abcselect nchar(48) 0select replace('angel','g','h') anhelselect replicate('abc',2) abcabcselect reverse('abcd') dcbaselect right('abcd',1) dselect rtrim('abc ') abcselect space(20) --返回有多個空格組成的字符串 select stuff('abc',2,1,'cc') acccselect upper('abcd') ABCD--日期和時間函數select current_timestamp --2013-04-14 18:34:04.657 返回當前的日期select dateadd( mm,1,'2013-04-14') 2013-05-14 00:00:00.000select datediff(mm,'2013-04-14','2014-04-14') 12個月select datename( dw,'2013-04-14') 星期日select datename( week,'2013-04-14') 16select datepart(mm,'2013-04-14') 四月select datepart(day,'2013-04-14') 14select month('2013-04-14') 4select year('2013-04-14') 2013select getdate() 2013-04-14 18:41:47.673 當前系統select getutcdate() 2013-04-14 10:42:47.090 表式當時utc的時間select isdate('2013-04-14') --判斷括號內的是不日期類型的不是返回0 是返回1select sysdatetime() 2013-04-14 18:46:00.3441457

select cast(1 as decimal(4,3)) --格式為四位有效數字, 三位小數 , 結果是1.000