第四天

MSSQL 語法

SELECT敘述的語法

select [col_name]

from [table_name]

where [conditions]

HAVING [col_name]

ORDER BY [col_name]

select * from dbo.employee

select * from dbo.department

select * → 一次取得整張資料表裡所有的資料

SELECT DISTINCT →去重複值

SELECT COUNT(DISTINCT COLUMNS) FROM TABLE →来计算非重复结果的数目

WHERE 子句用法

WHERE子句用來篩選COLUMN

可多個查詢條件式
BETWEEN .... AND ....運算子: 介於兩個值之間，包括兩個值
WHERE col_name| expr BETWEEN value1 AND value2
WHERE col_name| expr BETWEEN value1 AND value2
IN運算子: 必須在所列的值之中
WHERE col_name| expr IN (value1, value2, ...);