MySQL 筆記(四)DDL,DML 風格參考
阿新 • • 發佈:2018-04-30
count alter var color prim update upd phone row | character_set_connection | utf8 |
| character_set_database | utf8 |
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | latin1 |
| character_set_system | utf8 |
| character_sets_dir | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.00 sec)
便於快速 COPY ,以備不時之需。
▲ 在所有操作之前:
SET character_set_database=utf8;
確保 ↓
mysql> SHOW VARIABLES LIKE "%char%";
+--------------------------+----------------------------+
| Variable_name | Value |
+--------------------------+----------------------------+
| character_set_client | utf8 |
| character_set_database | utf8 |
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | latin1 |
| character_set_system | utf8 |
+--------------------------+----------------------------+
8 rows in set (0.00 sec)
▲ 創建數據庫:
CREATE DATABASE sql_lab;
▲ 然後創建表:
CREATE TABLE chucang ( chucang_no VARCHAR(12), enterprise_name VARCHAR(20), chucang_time DATE, chucang_typeCHAR(1) COMMENT ‘企業性質,Y 公有,N 私有‘, enterprise_address VARCHAR(50), delivery_car_no VARCHAR(12), chucang_sum DECIMAL(8,2), PRIMARY KEY(chucang_no) ) ENGINE=INNODB DEFAULT CHARSET=utf8; CREATE TABLE chucang_detail ( chucang_no VARCHAR(12), product_no VARCHAR(12), price DECIMAL(8,2), quantity INT, total DECIMAL(8,2), FOREIGN KEY (chucang_no) REFERENCES chucang(chucang_no) ) ENGINE=INNODB DEFAULT CHARSET=utf8;
PS. 別漏掉 DEFAULT CHARSET=utf8
▲ 確認表是否創建:
mysql> SHOW TABLES; +-------------------+ | Tables_in_sql_lab | +-------------------+ | chucang | | chucang_detail | +-------------------+ 2 rows in set (0.01 sec)
▲ 插入數據:
INSERT INTO chucang (chucang_no, enterprise_name, chucang_time, chucang_type, enterprise_address, delivery_car_no, chucang_sum) VALUES (‘10001‘, ‘enterprise_a‘, ‘1997-10-11‘, ‘Y‘, ‘????‘, ‘30005‘, 0.00), (‘10002‘, ‘enterprise_b‘, ‘1997-10-21‘, ‘Y‘, ‘shanghai‘, ‘30001‘, 0.00), (‘10003‘, ‘enterprise_c‘, ‘1997-10-22‘, ‘N‘, ‘beijin‘, ‘30003‘, 0.00), (‘10004‘, ‘enterprise_d‘, ‘1997-10-23‘, ‘Y‘, ‘shanghai‘, ‘30004‘, 0.00), (‘10005‘, ‘enterprise_e‘, ‘1997-10-24‘, ‘N‘, ‘guangdong‘, ‘30007‘, 0.00); INSERT INTO chucang_detail (chucang_no, product_no, price, quantity, total) VALUES (‘10002‘, ‘221‘, 30.5, 20, 0.00), (‘10003‘, ‘222‘, 31.5, 22, 0.00), (‘10004‘, ‘223‘, 40.5, 20, 0.00), (‘10001‘, ‘224‘, 41.5, 20, 0.00), (‘10005‘, ‘225‘, 43.5, 20, 0.00);
▲ 檢查數據:
SELECT * FROM chucang_detail LIMIT 3\G
▲ 修改表,插入一個新的字段/屬性/列:
ALTER TABLE chucang ADD enterprise_phone CHAR(20);
▲ 檢查是否修改成功:
mysql> DESCRIBE chucang;
▲ 更新數據:
UPDATE chucang_detail SET total = quantity * price;
UPDATE chucang x, chucang_detail y SET x.chucang_sum = y.total WHERE x.chucang_no = y.chucang_no; -- 多表示例 ↑ ↓ UPDATE chucang x SET x.chucang_sum = ( SELECT SUM(total) FROM chucang_detail y GROUP BY y.chucang_no HAVING y.chucang_no = x.chucang_no )
▲ 最簡單的查詢:
SELECT chucang_sum FROM chucang WHERE chucang_type = ‘Y‘
▲ 排序:
SELECT chucang_no, enterprise_name FROM chucang ORDER BY chucang_no
▲ 子查詢:
SELECT chucang_no FROM chucang_detail WHERE chucang_no NOT IN ( SELECT chucang_no FROM chucang )
▲ 分組過濾 & 聚集函數:
SELECT chucang_type, SUM(chucang_sum) FROM chucang GROUP BY chucang_type HAVING chucang_type = ‘Y‘
▲ 本題無關,聯表查詢示例:
SELECT employee_no, employee_name, product_name, quantity, price FROM employee x LEFT OUTER JOIN order_master y ON x.employee_no = y.saler_no LEFT OUTER JOIN order_detail z ON z.order_no = y.order_no LEFT OUTER JOIN product m ON m.product_no = z.product_no WHERE ( SELECT COUNT(DISTINCT product_no) FROM order_master w LEFT OUTER JOIN order_detail e ON w.order_no = e.order_no WHERE w.saler_no = x.employee_no) >= 5 ORDER BY employee_no
MySQL 筆記(四)DDL,DML 風格參考