SELECT * FROM ecs_goods WHERE goods_id = 1;SELECT goods_id, goods_name FROM ecs_goods WHERE goods_id = 1;SELECT goods_id,cat_id,goods_name FROM ecs_go ...
SELECT * FROM ecs_goods WHERE goods_id = 1;
SELECT goods_id, goods_name FROM ecs_goods WHERE goods_id = 1;
SELECT goods_id,cat_id,goods_name FROM ecs_goods WHERE cat_id != 3;
SELECT goods_id,cat_id,goods_name FROM ecs_goods WHERE cat_id <> 3;
SELECT goods_id,cat_id,goods_name,shop_price FROM ecs_goods WHERE shop_price > 3000;
SELECT goods_id,cat_id,goods_name,shop_price FROM ecs_goods WHERE shop_price <= 100;
SELECT goods_id,cat_id,goods_name,shop_price FROM ecs_goods WHERE cat_id = 4 OR cat_id = 3;
SELECT goods_id,cat_id,goods_name,shop_price FROM ecs_goods WHERE cat_id IN( 3, 4 );
SELECT goods_id,cat_id,goods_name,shop_price FROM ecs_goods WHERE shop_price BETWEEN 100 AND 858;
SELECT goods_id,cat_id,goods_name,shop_price FROM ecs_goods WHERE cat_id != 3 AND cat_id != 4
SELECT goods_id,cat_id,goods_name,shop_price FROM ecs_goods WHERE cat_id NOT IN( 3, 4 );
SELECT goods_id,cat_id,goods_name,shop_price FROM ecs_goods WHERE cat_id NOT BETWEEN 3 AND 4
SELECT goods_id,cat_id,goods_name,shop_price FROM ecs_goods WHERE ( shop_price > 100 AND shop_price < 300 )
OR ( shop_price > 1000 AND shop_price < 3000 );
SELECT goods_id,cat_id,goods_name,shop_price,click_count FROM ecs_goods WHERE (cat_id = 3 ) AND ( shop_price >= 1000 AND shop_price <= 3000 )
AND ( click_count > 5 )
SELECT * FROM ecs_goods WHERE cat_id IN ( 2, 3, 4, 5 )
SELECT goods_id,cat_id,goods_name FROM ecs_goods WHERE goods_name LIKE '諾基亞%'
#把表中欄位num取值範圍為20~29之間的值變成20【註：ecshop2.7.3沒有這個ecs_mian1這個表，可以自己創建一個，他就一個欄位num, int類型，然後填充一些測試數據】
UPDATE ecs_mian1 SET num = ( FLOOR( num / 10 ) * 10 ) WHERE num >= 20 AND num <= 29
#把表中欄位num取值範圍為30~39之間的值變成30
UPDATE ecs_mian1 SET num = ( FLOOR( num / 10 ) * 10 ) WHERE num BETWEEN 30 AND 39
#以”諾基亞"開頭的商品
SELECT goods_id, goods_name FROM ecs_goods WHERE goods_name LIKE '諾基亞%';
#截取"諾基亞"後面的商品名稱，並用"小米"開始 連接起來
SELECT goods_id, CONCAT( '小米', SUBSTRING( goods_name, 4 ) ) FROM ecs_goods WHERE goods_name LIKE '諾基亞%';
#截取"諾基亞"後面的商品名稱，並用"小米"開始 連接起來後更新
UPDATE ecs_goods SET goods_name = CONCAT( '小米', SUBSTRING( goods_name, 4 ) ) WHERE goods_name LIKE '諾基亞%'
#以上面的語句相反
UPDATE ecs_goods SET goods_name = CONCAT( '諾基亞', SUBSTRING( goods_name, 4 ) ) WHERE goods_name LIKE '小米%'
關於NULL:
SELECT NULL = NULL
SELECT NULL != NULL
#建表
CREATE TABLE ghost_user_info(
id INT( 3 ),
user_name VARCHAR( 20 )
)CHARSET utf8 ENGINE MYISAM;
#插入測試數據
INSERT INTO ghost_user_info VALUES( 1, '張三' );
INSERT INTO ghost_user_info VALUES( 2, NULL );
#user_name不等於NULL的記錄，不能這樣寫
SELECT * FROM ghost_user_info WHERE user_name != NULL
#user_name不等於NULL的記錄，應該這樣寫
SELECT * FROM ghost_user_info WHERE user_name IS NOT NULL
#同樣的，等於NULL的記錄應該是 IS NULL而不是 = NULL
SELECT * FROM ghost_user_info WHERE user_name = NULL
SELECT * FROM ghost_user_info WHERE user_name IS NULL
#統計函數
SELECT AVG( shop_price ) FROM ecs_goods;
SELECT MAX( shop_price ) FROM ecs_goods;
SELECT MIN( shop_price ) FROM ecs_goods;
SELECT COUNT(*) FROM ecs_goods;
SELECT SUM( shop_price ) / COUNT(*) FROM ecs_goods;
#積壓貨款
SELECT SUM( shop_price * goods_number ) FROM ecs_goods;
#統計每個分類的商品平均價格, group比較耗費資源（先按cat_id排序，再統計）
SELECT cat_id,AVG( shop_price ) FROM ecs_goods GROUP BY cat_id;
#查詢每個分類下，商品的數量
SELECT cat_id, COUNT(*) FROM ecs_goods GROUP BY cat_id;
#每個分類下最貴的產品
SELECT cat_id, MAX(shop_price) FROM ecs_goods GROUP BY cat_id;
#本店價格比市場價格小200以上的商品
SELECT goods_id, goods_name, market_price - shop_price FROM ecs_goods WHERE market_price - shop_price > 200
#下麵的語句，報錯（Unknown column 'discount_price' in 'where clause' ）,discount_price這個別名是結果集中(存在記憶體中）的，where後面的欄位需要是磁碟表中的欄位
SELECT goods_id, goods_name, ( market_price - shop_price ) AS discount_price FROM ecs_goods WHERE discount_price > 200
#可以用having關鍵字過濾查詢出來的結果集
SELECT goods_id, goods_name, ( market_price - shop_price ) AS discount_price FROM ecs_goods WHERE 1 HAVING discount_price > 200
#多列排序
SELECT goods_id, cat_id, goods_name, shop_price FROM ecs_goods ORDER BY cat_id ASC, shop_price DESC;
#查詢最新的商品1
SELECT goods_id, goods_name, cat_id FROM ecs_goods ORDER BY goods_id DESC LIMIT 0,1
#下麵兩句組合，等於後面的where子查詢
SELECT goods_Id, goods_name,cat_id FROM ecs_goods WHERE goods_id = 32
SELECT MAX( goods_id ) FROM ecs_goods;
#(where子查詢)查詢最新的商品2
SELECT goods_Id, goods_name,cat_id FROM ecs_goods WHERE goods_id = ( SELECT MAX( goods_id ) FROM ecs_goods );
#from子查詢：每一個分類下，最大的產品id( 最新的產品 )
SELECT goods_id, goods_name, cat_id FROM ecs_goods ORDER BY cat_id ASC, goods_id DESC
#把上面的語句 當前一個臨時的表，放在from後面 組成一個from子查詢
SELECT goods_id, goods_name, cat_id FROM ( SELECT goods_id, goods_name, cat_id FROM ecs_goods ORDER BY cat_id ASC, goods_id DESC ) AS tmp GROUP BY cat_id
