SQL語法學習筆記
Store_Information 表格
store_name |
Sales |
Date |
Los Angeles |
$1500 |
Jan-05-1999 |
San Diego |
$250 |
Jan-07-1999 |
San Francisco |
$300 |
Jan-08-1999 |
Boston |
$700 |
Jan-08-1999 |
語句1:SELECT "欄位名" FROM "表格名"
舉例:若要選出所有的店名 (store_Name),我們就打入:
SELECT store_name FROM Store_Information
結果:
store_name |
Los Angeles |
San Diego |
Los Angeles |
Boston |
我們一次可以讀取好幾個欄位,也可以同時由好幾個表格中選資料。
語句2:SELECT DISTINCT "欄位名" FROM "表格名"
舉例:若要在以下的表格,Store_Information,找出所有不同的店名時。
store_name |
Sales |
Date |
Los Angeles |
$1500 |
Jan-05-1999 |
San Diego |
$250 |
Jan-07-1999 |
San Francisco |
$300 |
Jan-08-1999 |
Boston |
$700 |
Jan-08-1999 |
SELECT DISTINCT store_name FROM Store_Information
結果:
store_name |
Los Angeles |
San Diego |
Boston |
語句3:SELECT "欄位名" FROM "表格名" WHERE "條件"
舉例:若我們要由以下的表格抓出營業額超過 $1,000 的資料。
store_name |
Sales |
Date |
Los Angeles |
$1500 |
Jan-05-1999 |
San Diego |
$250 |
Jan-07-1999 |
Los Angeles |
$300 |
Jan-08-1999 |
Boston |
$700 |
Jan-08-1999 |
我們就打入,
SELECT store_name FROM Store_Information WHERE Sales > 1000
結果:
結果:
store_name |
Los Angeles |