MySQL-查詢資料操作（DQL）
阿新 • • 發佈：2019-01-09
- SELECT查詢格式說明
SELECT select_expr [,select_expr...]
[
FROM tnl_name
[WHERE 條件]
[GROUP BY {col_name|position} [ASC|DESC], ... 分組]
[HAVING 條件 對分組結果進行二次篩選]
[ORDER BY {col_name|position} [ASC|DESC], ... 排序]
[LIMIT 限制條數]
]
資料庫：cms
資料表：cms_admin cms_cate cms_news cms_user provinces
- –查詢全部
SELECT * FROM user;
SELECT user.* FROM user; #查詢表user的所有資料
- –查詢欄位
SELECT id,username FROM cms_admin;
- –給表名起別名
SELECT id,username FROM cms_admin AS a;
SELECT id,username FROM cms_admin;
SELECT a.id,a.username,a.email,a.role FROM cms_admin AS a;
- –給欄位起別名
SELECT a.id AS '編號',username AS '使用者名稱',email AS '郵箱',role AS '角色' FROM cms_admin;
- –表別名和欄位別名結合起來
SELECT a.id AS i,a.username AS u,a.email AS e,a.role AS r FROM cms_admin AS a;
- –WHERE條件
- –指定範圍 BETWEEN AND NOT BETWEEN AND
- –查詢編號3~10之前的記錄
SELECT * FROM cms_user WHERE id BETWEEB 3 AND 10;
SELECT * FROM cms_user WHERE id NOT BETWEEB 3 AND 10;
- –指定集合 查詢編號為1,3,5,7,9,11,100的記錄
SELECT * FROM cms_user WHERE id IN(1,3,5,7,9,11,100);
SLEECT * FROM cms_user WHERE proId IN(1,5);
SELECT * FROM cms_user WHERE username IN('zhao','qian','sun');
- –匹配字元
–模糊查詢：
%：代表0個一個或者多個任意字元；
_：代表1個任意字元；
SELECT * FROM cms_user WHERE username LIKE '%天%';
SELECT * FROM cms_user WHERE username LIKE '張%';
- –查詢使用者名稱為3位的記錄
SELECT * FROM cms_user WHERE username LIKE '___';
SELECT * FROM cms_user WHERE username LIKE '_I%';
- –查詢使用者名稱為wang並且密碼為tian的使用者
SELECT * FROM cms_user WHERE username='wang' AND password='tian';
- –查詢編號大於等於3並且年齡不為NULL的使用者
SELECT * FROM cms_user WHERE id>=3 AND age IS NOT NULL;
- –查詢編號大於等於3並且年齡不為NULL的使用者並且proId等於3
SELECT * FROM cms_user WHERE id>=3 AND age IS NOT NULL AND proId=3;
- –查詢編號在5~10且使用者名稱為4位的使用者
SELECT * FROM cms_user WHERE id BETWEEN 5 AND 10 AND username LIKE '____';
- –查詢使用者名稱以張開頭，或者是使用者所在省份為2,4的記錄
SELECT * FROM cms_user WHERE username LIKE '張%' OR proId IN(2,4);
- –分組 GROUP BY
SELECT * FROM cms_user GROUP BY proId;
SELECT * FROM cms_user GROUP BY sex;
- –按照多個欄位分組；先按照proId分，在組內按照sex分
SELECT * FROM cms_user GROUP BY proId,sex;
- –GROUP BY配合GROUP_CONCAT()得到分組詳情
- –查詢id，sex，使用者名稱詳情，按照性別分組
SELECT id,sex,GROUP_CONCAT(username) FROM cms_user GROUP BY sex;
- –查詢proId，性別詳情，註冊時間詳情，使用者名稱詳情，按照proId分組
SELECT proId,GROUP_CONCAT(username),GROUP_CONCAT(sex),GROUP_CONCAT(regTime) FROM cms_user GROUP BY proId;
- –GROUP BY配合聚合函式COUNT() MAX() MIN() AVG() SUM()
- –查詢編號，sex，使用者名稱詳情以及組中總人數按照sex分組
SELECT id,sex,GROUP_CONCAT(username) AS users,COUNT(*) AS totalUsers FROM cms_user GROUP BY sex;
- –統計表中所有記錄
SEELCT COUNT(*) AS totalUsers FROM cms_user;
SEELCT COUNT(id) AS totalUsers FROM cms_user;
- –COUNT()函式不統計NULL值
SELECT COUNT(age) AS totalUser FROM cms_user;
- –查詢編號，性別，使用者名稱詳情，組中總人數，組中最大年齡，組中最小年齡，平均年齡，以及年齡總和按照性別分組
SELECT id,sex,
GROUP_CONCAT(username),
COUNT(*) AS totalUsers,
MAX(age) AS max_age,
MIN(age) AS min_age,
AVG(age) AS ave_age,
SUM(age) AS sum_age
FROM cms_user
GROUP BY sex;
- –GROUP BY配合 WITH ROLLUP 記錄上面所有記錄的總和
SELECT id,sex,
GROUP_CONCAT(username),
COUNT(*) AS totalUsers,
MAX(age) AS max_age,
MIN(age) AS min_age,
AVG(age) AS ave_age,
SUM(age) AS sum_age
FROM cms_user
GROUP BY sex WITH ROLLUP;
- –HAVING 子句對分組結果進行二次篩選
- –查詢性別，使用者名稱詳情組中總人數，最大年齡，年齡總和，按照性別分組
SELECT sex,
GROUP_CONCAT(username) AS users,
COUNT(*) AS totalUsers,
MAX(age) AS max_age,
SUM(age) AS sum_age
FROM cms_user
GROUP BY sex;
- –查詢組中人數大於2的；對上一條sql結果進行二次篩選
SELECT sex,
GROUP_CONCAT(username) AS users,
COUNT(*) AS totalUsers,
MAX(age) AS max_age,
SUM(age) AS sum_age
FROM cms_user
GROUP BY sex
HAVING COUNT(*) > 2;
SELECT sex,
GROUP_CONCAT(username) AS users,
COUNT(*) AS totalUsers,
MAX(age) AS max_age,
SUM(age) AS sum_age
FROM cms_user
GROUP BY sex
HAVING COUNT(*) > 2 AND MAX(age) > 60;
SELECT sex,
GROUP_CONCAT(username) AS users,
COUNT(*) AS totalUsers,
MAX(age) AS max_age,
SUM(age) AS sum_age
FROM cms_user
WHERE id >= 2
GROUP BY sex
HAVING COUNT(*) > 2 AND MAX(age) > 60;
-
–ORDER BY 對查詢結果進行排序
DESC 降序，ASC 升序
SELECT * FROM cms_user ORDER BY id DESC;
SELECT * FROM cms_user ORDER BY age ASC;
- –按照年齡升序，id降序排列
SELECT * FROM cms_user ORDER BY age ASC,id DESC;
- –取隨機數
SELECT * FROM cms_user ORDER BY RAND();
-
–LIMIT 限制查詢結果顯示條數
LIMIT 顯示條數
LIMIT 偏移量,顯示條數 #實現分頁顯示
SELECT * FROM cms_user LIMIT 5;
SELECT * FROM cms_user LIMIT 1;
SELECT * FROM cms_user LIMIT 0,1;
- –總結查詢sql
SELECT id,sex,age,GROUP_CONCAT(username),
COUNT(*) AS totalUsers,
MAX(age) AS max_age,
MIN(age) AS min_age,
AVE(age) AS ave_age,
SUM(age) AS sum_age
FROM cms_user
WHERE id >= 1
GROUP BY sex
HAVING COUNT(*) >= 2
ORDER BY age DESC
LIMIT 0,3;