簡單總結 MySQL數學函數
- 怪我咯原創
- 2017-04-01 10:29:051473瀏覽
1. ABS(x): 傳回x的絕對值
mysql> select ABS(1), ABS(-1), ABS(0); +--------+---------+--------+ | ABS(1) | ABS(-1) | ABS(0) | +--------+---------+--------+ | 1 | 1 | 0 | +--------+---------+--------+
2. PI(): 傳回圓周率
mysql> select PI(); +----------+ | PI() | +----------+ | 3.141593 | +----------+
3. SQRT(x): 傳回x的平方根，要求（x為非負數，回傳NULL）
mysql> select SQRT(49), SQRT(0), SQRT(-49); +----------+---------+-----------+ | SQRT(49) | SQRT(0) | SQRT(-49) | +----------+---------+-----------+ | 7 | 0 | NULL | +----------+---------+-----------+
4. MOD(x,y): 求餘函數，返回x被y除後的餘數；對於帶有小數部分的資料值也起作用，它返回除法運算後的精確餘數。
mysql> select MOD(31,8), MOD(21,-8), MOD(-7,2), MOD(-7,-2), MOD(45.5,6); +-----------+------------+-----------+------------+-------------+ | MOD(31,8) | MOD(21,-8) | MOD(-7,2) | MOD(-7,-2) | MOD(45.5,6) | +-----------+------------+-----------+------------+-------------+ | 7 | 5 | -1 | -1 | 3.5 | +-----------+------------+-----------+------------+-------------+
5. CEIL(X): 傳回不小X的最小整數值，傳回值轉為一個BIGINT.
mysql> select CEIL(-3.35), CEIL(3.35); +-------------+------------+ | CEIL(-3.35) | CEIL(3.35) | +-------------+------------+ | -3 | 4 | +-------------+------------+
6. CEILING(X): 同CEIL(X)
mysql> select CEILING(-3.35), CEILING(3.35); +----------------+---------------+ | CEILING(-3.35) | CEILING(3.35) | +----------------+---------------+ | -3 | 4 | +----------------+---------------+
7. FLOOR(X):傳回不大於X的最大整數值，傳回值轉為一個BIGINT.
mysql> select FLOOR(-3.35), FLOOR(3.35); +--------------+-------------+ | FLOOR(-3.35) | FLOOR(3.35) | +--------------+-------------+ | -4 | 3 | +--------------+-------------+
8. RAND()和RAND(X)
RAND(X ) 傳回一個隨機浮點數值，範圍在０～１之間，X為整數，它被稱為種子值，用來產生重複序列。即當Ｘ值相同時，產生的隨機數也相同；
mysql> select RAND(10), RAND(10), RAND(2), RAND(-2); +--------------------+--------------------+--------------------+--------------------+ | RAND(10) | RAND(10) | RAND(2) | RAND(-2) | +--------------------+--------------------+--------------------+--------------------+ | 0.6570515219653505 | 0.6570515219653505 | 0.6555866465490187 | 0.6548542125661431 | +--------------------+--------------------+--------------------+--------------------+
RAND(): 不帶參數的RAND()每次產生不同０～１之間的隨機數
mysql> SELECT RAND(), RAND(), RAND(); +--------------------+--------------------+---------------------+ | RAND() | RAND() | RAND() | +--------------------+--------------------+---------------------+ | 0.6931893636409094 | 0.5147262984092592 | 0.49406343185721285 | +--------------------+--------------------+---------------------+
9. ROUND(X)和ROUND(X,Y): 四捨五入函數，對Ｘ值依Ｙ進行四捨五入，Ｙ可以省略，預設值為０;若Ｙ不為０，則保留小數點後面指定Ｙ位。
mysql> select ROUND(-1.14), ROUND(-1.9), ROUND(1.14), ROUND(1.9); +--------------+-------------+-------------+------------+ | ROUND(-1.14) | ROUND(-1.9) | ROUND(1.14) | ROUND(1.9) | +--------------+-------------+-------------+------------+ | -1 | -2 | 1 | 2 | +--------------+-------------+-------------+------------+ mysql> select ROUND(1.38,1), ROUND(1.38,0), ROUND(232.38,-1), ROUND(232.38,-2); +---------------+---------------+------------------+------------------+ | ROUND(1.38,1) | ROUND(1.38,0) | ROUND(232.38,-1) | ROUND(232.38,-2) | +---------------+---------------+------------------+------------------+ | 1.4 | 1 | 230 | 200 | +---------------+---------------+------------------+------------------+
10. TRUNCATE(X,Y): 與ROUND(X,Y)功能類似，但不進行四捨五入，只進行截取。
mysql> select TRUNCATE(1.33,1), TRUNCATE(1.99,1), TRUNCATE(1.99,0), TRUNCATE(19.99,-1); +------------------+------------------+------------------+--------------------+ | TRUNCATE(1.33,1) | TRUNCATE(1.99,1) | TRUNCATE(1.99,0) | TRUNCATE(19.99,-1) | +------------------+------------------+------------------+--------------------+ | 1.3 | 1.9 | 1 | 10 | +------------------+------------------+------------------+--------------------+
11. SIGN(X): 傳回參數Ｘ的符號，Ｘ的值為負、零或正數時傳回結果依序為－１，０或１
mysql> select SIGN(-21), SIGN(-0),SIGN(0), SIGN(0.0), SIGN(21); +-----------+----------+---------+-----------+----------+ | SIGN(-21) | SIGN(-0) | SIGN(0) | SIGN(0.0) | SIGN(21) | +-----------+----------+---------+-----------+----------+ | -1 | 0 | 0 | 0 | 1 | +-----------+----------+---------+-----------+----------+
12. POW(X,Y), POWER(X,Y)和EXP(X)
POW(X,Y )與POWER(X,Y)函數相同，用於傳回Ｘ的Ｘ次乘方的結果值
mysql> select pow(2,2), pow(2,-2), pow(-2,2), pow(-2,-2); +----------+-----------+-----------+------------+ | pow(2,2) | pow(2,-2) | pow(-2,2) | pow(-2,-2) | +----------+-----------+-----------+------------+ | 4 | 0.25 | 4 | 0.25 | +----------+-----------+-----------+------------+ mysql> select power(2,2), power(2,-2), power(-2,2), power(-2,-2); +------------+-------------+-------------+--------------+ | power(2,2) | power(2,-2) | power(-2,2) | power(-2,-2) | +------------+-------------+-------------+--------------+ | 4 | 0.25 | 4 | 0.25 | +------------+-------------+-------------+--------------+
EXP(X): 傳回e的Ｘ乘方後的值:
mysql> select EXP(3), EXP(0), EXP(-3); +-------------------+--------+---------------------+ | EXP(3) | EXP(0) | EXP(-3) | +-------------------+--------+---------------------+ | 20.08553692318767 | 1 | 0.04978706836786393 | +-------------------+--------+---------------------+
13. LOG(X)和LOG10(X): 對數運算函數（Ｘ必須為正數），LOG(X)-傳回Ｘ的自然對數(X相對於基數e的對數) LOG10(X)-傳回x的基數為10的對數：
mysql> select LOG(-3), LOG(0), LOG(3), LOG10(-100), LOG10(0), LOG10(100); +---------+--------+--------------------+-------------+----------+------------+ | LOG(-3) | LOG(0) | LOG(3) | LOG10(-100) | LOG10(0) | LOG10(100) | +---------+--------+--------------------+-------------+----------+------------+ | NULL | NULL | 1.0986122886681098 | NULL | NULL | 2 | +---------+--------+--------------------+-------------+----------+------------+
14. RADIANS(X) 和DEGREES(X): 角度與弧度轉換函數
mysql> select RADIANS(90), RADIANS(180), DEGREES(PI()), DEGREES(PI()/2); +--------------------+-------------------+---------------+-----------------+ | RADIANS(90) | RADIANS(180) | DEGREES(PI()) | DEGREES(PI()/2) | +--------------------+-------------------+---------------+-----------------+ | 1.5707963267948966 | 3.141592653589793 | 180 | 90 | +--------------------+-------------------+---------------+-----------------+
15. SIN(X), ASIN(X), COS(X), ACOS(X), TAN(X), ATAN(X ), COT(X)
SIN(X): 正弦函數，其中Ｘ為弧度值
ASIN(X): 反正弦函數其中Ｘ必須在－１到１之間
COS(X): 餘弦函數，其中Ｘ為弧度值
ACOS(X): 反餘弦函數其中Ｘ必須在－１到１之間
TAN( X): 正切函數，其中Ｘ為弧度值
ATAN(X): 反正切函數，ATAN(X)與TAN(X)互為反函數
COT(X): 餘切函數，函數COT和TAN互為倒函數
mysql> select SIGN(PI()/2),ASIN(1),COS(PI()), ACOS(-1), TAN(PI()/4), ATAN(1), COT(0.5); +--------------+--------------------+-----------+-------------------+--------------------+--------------------+-------------------+ | SIGN(PI()/2) | ASIN(1) | COS(PI()) | ACOS(-1) | TAN(PI()/4) | ATAN(1) | COT(0.5) | +--------------+--------------------+-----------+-------------------+--------------------+--------------------+-------------------+ | 1 | 1.5707963267948966 | -1 | 3.141592653589793 | 0.9999999999999999 | 0.7853981633974483 | 1.830487721712452 | +--------------+--------------------+-----------+-------------------+--------------------+--------------------+-------------------+
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