SQL 函數(shù)
AVG()
求某列的平均數(shù)
SELECT AVG([列名]) FROM [數(shù)據(jù)表]
COUNT()
統(tǒng)計(jì)指定列的數(shù)目,如COUNT(*)則表示統(tǒng)計(jì)整個(gè)數(shù)據(jù)表的記錄數(shù)
COUNT(DISTINCT [列名])
相同值的列只計(jì)算一次
UCASE()
將字段的值轉(zhuǎn)換為大寫
SELECT UCASE(列名) FROM 數(shù)據(jù)表;
(舉例)
image
SELECT UCASE(_Varchar) FROM number;
(結(jié)果)
image
LCASE()
將字段的值轉(zhuǎn)換為小寫
SELECT LCASE(列名) FROM 數(shù)據(jù)表;
(舉例)
image
SELECT LCASE(_Varchar) FROM number;
(結(jié)果)
image
LEN()
返回文本字段中值的長(zhǎng)度
SELECT LEN(列名) FROM 數(shù)據(jù)表;
(舉例)
image
SELECT _Varchar, LENGTH(_Varchar) FROM number;
(結(jié)果)
image
ROUND()
將數(shù)值字段舍入為指定的小數(shù)位數(shù)
SELECT ROUND(列名, 小數(shù)位) FROM 數(shù)據(jù)表;
(舉例)
image
SELECT ROUND(_Double, 3), _Varchar FROM number;
(結(jié)果)
image
NOW()
返回當(dāng)前系統(tǒng)的日期和時(shí)間
SELECT NOW() FROM數(shù)據(jù)表;
(舉例)
image
SELECT _Double, _Varchar, NOW() FROM number;
(結(jié)果)
image