博主不想写字并向你仍来了一堆代码
1-6
SQL——结构化查询语言，Structured Query Language；
基本按列查询：
mysql> SELECT prod_id,prod_name,prod_desc -> FROM products -> ORDER BY prod_id; +---------+---------------------+-----------------------------------------------------------------------+ | prod_id | prod_name | prod_desc | +---------+---------------------+-----------------------------------------------------------------------+ | BNBG01 | Fish bean bag toy | Fish bean bag toy, complete with bean bag worms with which to feed it | | BNBG02 | Bird bean bag toy | Bird bean bag toy, eggs are not included | | BNBG03 | Rabbit bean bag toy | Rabbit bean bag toy, comes with bean bag carrots | | BR01 | 8 inch teddy bear | 8 inch teddy bear, comes with cap and jacket | | BR02 | 12 inch teddy bear | 12 inch teddy bear, comes with cap and jacket | | BR03 | 18 inch teddy bear | 18 inch teddy bear, comes with cap and jacket | | RGAN01 | Raggedy Ann | 18 inch Raggedy Ann doll | | RYL01 | King doll | 12 inch king doll with royal garments and crown | | RYL02 | Queen doll | 12 inch queen doll with royal garments and crown | +---------+---------------------+-----------------------------------------------------------------------+
mysql> SELECT prod_id,prod_name,prod_desc
-> FROM products
-> ORDER BY prod_price,prod_name;
+---------+---------------------+-----------------------------------------------------------------------+
| prod_id | prod_name | prod_desc |
+---------+---------------------+-----------------------------------------------------------------------+
| BNBG02 | Bird bean bag toy | Bird bean bag toy, eggs are not included |
| BNBG01 | Fish bean bag toy | Fish bean bag toy, complete with bean bag worms with which to feed it |
| BNBG03 | Rabbit bean bag toy | Rabbit bean bag toy, comes with bean bag carrots |
| RGAN01 | Raggedy Ann | 18 inch Raggedy Ann doll |
| BR01 | 8 inch teddy bear | 8 inch teddy bear, comes with cap and jacket |
| BR02 | 12 inch teddy bear | 12 inch teddy bear, comes with cap and jacket |
| RYL01 | King doll | 12 inch king doll with royal garments and crown |
| RYL02 | Queen doll | 12 inch queen doll with royal garments and crown |
| BR03 | 18 inch teddy bear | 18 inch teddy bear, comes with cap and jacket |
+---------+---------------------+-----------------------------------------------------------------------+
9 rows in set (0.00 sec)
mysql> SELECT prod_id,prod_name,prod_desc
-> FROM products
-> ORDER BY prod_price,prod_name DESC;
+---------+---------------------+-----------------------------------------------------------------------+
| prod_id | prod_name | prod_desc |
+---------+---------------------+-----------------------------------------------------------------------+
| BNBG03 | Rabbit bean bag toy | Rabbit bean bag toy, comes with bean bag carrots |
| BNBG01 | Fish bean bag toy | Fish bean bag toy, complete with bean bag worms with which to feed it |
| BNBG02 | Bird bean bag toy | Bird bean bag toy, eggs are not included |
| RGAN01 | Raggedy Ann | 18 inch Raggedy Ann doll |
| BR01 | 8 inch teddy bear | 8 inch teddy bear, comes with cap and jacket |
| BR02 | 12 inch teddy bear | 12 inch teddy bear, comes with cap and jacket |
| RYL02 | Queen doll | 12 inch queen doll with royal garments and crown |
| RYL01 | King doll | 12 inch king doll with royal garments and crown |
| BR03 | 18 inch teddy bear | 18 inch teddy bear, comes with cap and jacket |
+---------+---------------------+-----------------------------------------------------------------------+
高级一点的过滤查询，WHERE,ORDER,IN,NOT,AND,OR,BETWEEN,NULL:
mysql> SELECT prod_id,prod_name,prod_desc -> FROM products -> WHERE prod_price IS NULL; Empty set (0.00 sec) mysql> SELECT prod_id,prod_name,prod_desc -> FROM products -> WHERE (vend_id <> 'DLL01' OR prod_id LIKE 'BR%') AND prod_price BETWEEN 3 AND 10; +---------+--------------------+--------------------------------------------------+ | prod_id | prod_name | prod_desc | +---------+--------------------+--------------------------------------------------+ | BR01 | 8 inch teddy bear | 8 inch teddy bear, comes with cap and jacket | | BR02 | 12 inch teddy bear | 12 inch teddy bear, comes with cap and jacket | | RYL01 | King doll | 12 inch king doll with royal garments and crown | | RYL02 | Queen doll | 12 inch queen doll with royal garments and crown | +---------+--------------------+--------------------------------------------------+ 4 rows in set (0.00 sec) mysql> SELECT prod_id,prod_name,prod_desc -> FROM products -> WHERE vend_id IN ('DLL01','BRS01') -> ORDER BY prod_name; +---------+---------------------+-----------------------------------------------------------------------+ | prod_id | prod_name | prod_desc | +---------+---------------------+-----------------------------------------------------------------------+ | BR02 | 12 inch teddy bear | 12 inch teddy bear, comes with cap and jacket | | BR03 | 18 inch teddy bear | 18 inch teddy bear, comes with cap and jacket | | BR01 | 8 inch teddy bear | 8 inch teddy bear, comes with cap and jacket | | BNBG02 | Bird bean bag toy | Bird bean bag toy, eggs are not included | | BNBG01 | Fish bean bag toy | Fish bean bag toy, complete with bean bag worms with which to feed it | | BNBG03 | Rabbit bean bag toy | Rabbit bean bag toy, comes with bean bag carrots | | RGAN01 | Raggedy Ann | 18 inch Raggedy Ann doll | +---------+---------------------+-----------------------------------------------------------------------+ 7 rows in set (0.00 sec) mysql> SELECT prod_id,prod_name,prod_desc -> FROM products -> WHERE vend_id NOT IN ('DLL01','BRS01') -> ORDER BY prod_name; +---------+------------+--------------------------------------------------+ | prod_id | prod_name | prod_desc | +---------+------------+--------------------------------------------------+ | RYL01 | King doll | 12 inch king doll with royal garments and crown | | RYL02 | Queen doll | 12 inch queen doll with royal garments and crown | +---------+------------+--------------------------------------------------+ 2 rows in set (0.00 sec)
通配符，%,_,[]（实测MySQL我这里不支持。。。）
不要过分使用通配符（和*一样）
不要把通配符放在搜索的开始处
mysql> SELECT prod_id,prod_name,prod_desc -> FROM products -> WHERE prod_name LIKE '__ inch teddy bear' OR prod_name LIKE 'Fish%'; +---------+--------------------+-----------------------------------------------------------------------+ | prod_id | prod_name | prod_desc | +---------+--------------------+-----------------------------------------------------------------------+ | BR02 | 12 inch teddy bear | 12 inch teddy bear, comes with cap and jacket | | BR03 | 18 inch teddy bear | 18 inch teddy bear, comes with cap and jacket | | BNBG01 | Fish bean bag toy | Fish bean bag toy, complete with bean bag worms with which to feed it | +---------+--------------------+-----------------------------------------------------------------------+ 3 rows in set (0.00 sec) mysql> SELECT * -> FROM customers; +------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+ | cust_id | cust_name | cust_address | cust_city | cust_state | cust_zip | cust_country | cust_contact | cust_email | +------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+ | 1000000001 | Village Toys | 200 Maple Lane | Detroit | MI | 44444 | USA | John Smith | sales@villagetoys.com | | 1000000002 | Kids Place | 333 South Lake Drive | Columbus | OH | 43333 | USA | Michelle Green | NULL | | 1000000003 | Fun4All | 1 Sunny Place | Muncie | IN | 42222 | USA | Jim Jones | jjones@fun4all.com | | 1000000004 | Fun4All | 829 Riverside Drive | Phoenix | AZ | 88888 | USA | Denise L. Stephens | dstephens@fun4all.com | | 1000000005 | The Toy Store | 4545 53rd Street | Chicago | IL | 54545 | USA | Kim Howard | NULL | +------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+ 5 rows in set (0.00 sec) mysql> SELECT cust_contact -> FROM customers -> WHERE cust_contact LIKE '[JM]%' -> ORDER BY cust_id; Empty set (0.00 sec) mysql> SELECT cust_contact -> FROM customers -> WHERE cust_contact LIKE '[JM]%' -> ORDER BY cust_contact; Empty set (0.00 sec) mysql> SELECT cust_contact -> FROM customers -> WHERE cust_contact LIKE '[^JM]%' -> ORDER BY cust_contact; Empty set (0.00 sec)
MySQL的计算字段：CONCAT(),+-*/,AS，TRIM()
别个DB可能是+或者||，更好读？？不是很懂，反正MySQL不得行
mysql> SELECT vend_name + '('+vend_country+')' -> FROM vendors -> ORDER BY vend_name; +----------------------------------+ | vend_name + '('+vend_country+')' | +----------------------------------+ | 0 | | 0 | | 0 | | 0 | | 0 | | 0 | +----------------------------------+ 6 rows in set, 24 warnings (0.00 sec) mysql> SELECT vend_name + '|' + vend_country + '|' -> FROM vendors -> ORDER BY vend_name; +--------------------------------------+ | vend_name + '|' + vend_country + '|' | +--------------------------------------+ | 0 | | 0 | | 0 | | 0 | | 0 | | 0 | +--------------------------------------+ 6 rows in set, 24 warnings (0.00 sec) mysql> SELECT * FROM vendors; +---------+-----------------+-----------------+------------+------------+----------+--------------+ | vend_id | vend_name | vend_address | vend_city | vend_state | vend_zip | vend_country | +---------+-----------------+-----------------+------------+------------+----------+--------------+ | BRS01 | Bears R Us | 123 Main Street | Bear Town | MI | 44444 | USA | | BRE02 | Bear Emporium | 500 Park Street | Anytown | OH | 44333 | USA | | DLL01 | Doll House Inc. | 555 High Street | Dollsville | CA | 99999 | USA | | FRB01 | Furball Inc. | 1000 5th Avenue | New York | NY | 11111 | USA | | FNG01 | Fun and Games | 42 Galaxy Road | London | NULL | N16 6PS | England | | JTS01 | Jouets et ours | 1 Rue Amusement | Paris | NULL | 45678 | France | +---------+-----------------+-----------------+------------+------------+----------+--------------+ 6 rows in set (0.00 sec) mysql> SELECT vend_name || ' ( '||vend_country || ' ) ' -> FROM vendors -> ORDER BY vend_name; +--------------------------------------------+ | vend_name || ' ( '||vend_country || ' ) ' | +--------------------------------------------+ | 0 | | 0 | | 0 | | 0 | | 0 | | 0 | +--------------------------------------------+ 6 rows in set, 24 warnings (0.00 sec) mysql> SELECT CONCAT(vend_name,vend_country) -> FROM vendors -> ORDER BY vend_name; +--------------------------------+ | CONCAT(vend_name,vend_country) | +--------------------------------+ | Bear EmporiumUSA | | Bears R UsUSA | | Doll House Inc.USA | | Fun and GamesEngland | | Furball Inc.USA | | Jouets et oursFrance | +--------------------------------+ 6 rows in set (0.00 sec) mysql> SELECT CONCAT(vend_name,'(',vend_country,')') -> FROM vendors -> ORDER BY vend_name; +----------------------------------------+ | CONCAT(vend_name,'(',vend_country,')') | +----------------------------------------+ | Bear Emporium(USA) | | Bears R Us(USA) | | Doll House Inc.(USA) | | Fun and Games(England) | | Furball Inc.(USA) | | Jouets et ours(France) | +----------------------------------------+ 6 rows in set (0.00 sec) mysql> SELECT vend_name, -> CONCAT(vend_address,',',vend_city,',',vend_state,',',vend_country) AS VendorsInfo, -> vend_zip -> FROM vendors -> ORDER BY vend_zip,vend_name DESC; +-----------------+-----------------------------------+----------+ | vend_name | VendorsInfo | vend_zip | +-----------------+-----------------------------------+----------+ | Furball Inc. | 1000 5th Avenue,New York,NY,USA | 11111 | | Bear Emporium | 500 Park Street,Anytown,OH,USA | 44333 | | Bears R Us | 123 Main Street,Bear Town,MI,USA | 44444 | | Jouets et ours | NULL | 45678 | | Doll House Inc. | 555 High Street,Dollsville,CA,USA | 99999 | | Fun and Games | NULL | N16 6PS | +-----------------+-----------------------------------+----------+ 6 rows in set (0.00 sec) mysql> SELECT prod_id,quantity,item_price, -> quantity*item_price AS sum_price -> FROM orderitems -> WHERE order_num=20008; +---------+----------+------------+-----------+ | prod_id | quantity | item_price | sum_price | +---------+----------+------------+-----------+ | RGAN01 | 5 | 4.99 | 24.95 | | BR03 | 5 | 11.99 | 59.95 | | BNBG01 | 10 | 3.49 | 34.90 | | BNBG02 | 10 | 3.49 | 34.90 | | BNBG03 | 10 | 3.49 | 34.90 | +---------+----------+------------+-----------+ 5 rows in set (0.00 sec)
使用数据处理函数：CURDATE(),YEAR(),UPPER(),TRIM(),ABS()
不同的DBMS的函数不是很一样，所以，使用函数的SQL代码移植性不好，如果一定要用，记得写清楚注释：
mysql> SELECT CONCAT(prod_name,'+',CURDATE()) -> FROM products; +---------------------------------+ | CONCAT(prod_name,'+',CURDATE()) | +---------------------------------+ | 8 inch teddy bear+2016-08-04 | | 12 inch teddy bear+2016-08-04 | | 18 inch teddy bear+2016-08-04 | | Fish bean bag toy+2016-08-04 | | Bird bean bag toy+2016-08-04 | | Rabbit bean bag toy+2016-08-04 | | Raggedy Ann+2016-08-04 | | King doll+2016-08-04 | | Queen doll+2016-08-04 | +---------------------------------+ 9 rows in set (0.00 sec) mysql> SELECT order_num -> FROM orders -> WHERE YEAR(order_date)=2004; +-----------+ | order_num | +-----------+ | 20005 | | 20006 | | 20007 | | 20008 | | 20009 | +-----------+ 5 rows in set (0.00 sec) mysql> SELECT UPPER(price_name) AS Name,prod_price -> FROM products -> ORDER BY prod_name; ERROR 1054 (42S22): Unknown column 'price_name' in 'field list' mysql> SELECT UPPER(prod_name) AS Name,prod_price -> FROM products -> ORDER BY prod_name; +---------------------+------------+ | Name | prod_price | +---------------------+------------+ | 12 INCH TEDDY BEAR | 8.99 | | 18 INCH TEDDY BEAR | 11.99 | | 8 INCH TEDDY BEAR | 5.99 | | BIRD BEAN BAG TOY | 3.49 | | FISH BEAN BAG TOY | 3.49 | | KING DOLL | 9.49 | | QUEEN DOLL | 9.49 | | RABBIT BEAN BAG TOY | 3.49 | | RAGGEDY ANN | 4.99 | +---------------------+------------+ 9 rows in set (0.00 sec)
聚集函数：COUNT(),AVG(),MAX(),MIN(),SUM():
mysql> SELECT UPPER(prod_name) AS P_Name,AVG(prod_price) AS P_Price -> FROM products -> WHERE prod_price BETWEEN 2 AND 10; +-------------------+----------+ | P_Name | P_Price | +-------------------+----------+ | 8 INCH TEDDY BEAR | 6.177500 | +-------------------+----------+ 1 row in set (0.00 sec) mysql> SELECT UPPER(prod_name) AS P_Name,AVG(prod_price) AS P_Price -> FROM products; +-------------------+----------+ | P_Name | P_Price | +-------------------+----------+ | 8 INCH TEDDY BEAR | 6.823333 | +-------------------+----------+ 1 row in set (0.00 sec) mysql> SELECT AVG(prod_price) AS P_Price -> FROM products; +----------+ | P_Price | +----------+ | 6.823333 | +----------+ 1 row in set (0.00 sec) mysql> SELECT COUNT(*) AS num_cust -> FROM customers; +----------+ | num_cust | +----------+ | 5 | +----------+ 1 row in set (0.00 sec) mysql> SELECT COUNT(*) AS Items, -> AVG(DISTINCT prod_price) AS price_avg, -> MAX(prod_price) AS price_max, -> MIN(prod_price) AS price_min -> FROM products; +-------+-----------+-----------+-----------+ | Items | price_avg | price_max | price_min | +-------+-----------+-----------+-----------+ | 9 | 7.490000 | 11.99 | 3.49 | +-------+-----------+-----------+-----------+ 1 row in set (0.00 sec)
分组：GROUP BY,HAVING;注意各种语句的顺序问题SELECT->FROM->WHERE->GROUP BY->HAVING->ORDER BY
mysql> SELECT prod_name,COUNT(*) AS num_prod
-> FROM products -> GROUP BY vend_id; +-------------------+----------+ | prod_name | num_prod | +-------------------+----------+ | 8 inch teddy bear | 3 | | Fish bean bag toy | 4 | | King doll | 2 | +-------------------+----------+ 3 rows in set (0.00 sec) mysql> SELECT prod_price,COUNT(*) AS num_price -> FROM products -> GROUP BY prod_price; +------------+-----------+ | prod_price | num_price | +------------+-----------+ | 3.49 | 3 | | 4.99 | 1 | | 5.99 | 1 | | 8.99 | 1 | | 9.49 | 2 | | 11.99 | 1 | +------------+-----------+ 6 rows in set (0.00 sec) mysql> SELECT prod_price,COUNT(*) AS num_price -> FROM products -> GROUP BY prod_price -> HAVING COUNT(*)>=2 -> ORDER BY prod_price DESC; +------------+-----------+ | prod_price | num_price | +------------+-----------+ | 9.49 | 2 | | 3.49 | 3 | +------------+-----------+ 2 rows in set (0.00 sec) mysql> SELECT prod_name,COUNT(*) AS num_prod -> FROM products -> WHERE prod_price>=3 -> GROUP BY prod_name -> HAVING COUNT(*)>=2 -> ORDER BY prod_price DESC; Empty set (0.00 sec) mysql> SELECT prod_name,prod_price,COUNT(*) AS num_prod -> FROM products -> GROUP BY prod_name; +---------------------+------------+----------+ | prod_name | prod_price | num_prod | +---------------------+------------+----------+ | 12 inch teddy bear | 8.99 | 1 | | 18 inch teddy bear | 11.99 | 1 | | 8 inch teddy bear | 5.99 | 1 | | Bird bean bag toy | 3.49 | 1 | | Fish bean bag toy | 3.49 | 1 | | King doll | 9.49 | 1 | | Queen doll | 9.49 | 1 | | Rabbit bean bag toy | 3.49 | 1 | | Raggedy Ann | 4.99 | 1 | +---------------------+------------+----------+ 9 rows in set (0.00 sec) mysql> SELECT prod_name,prod_price,COUNT(*) AS num_prod -> FROM products -> GROUP BY prod_price; +--------------------+------------+----------+ | prod_name | prod_price | num_prod | +--------------------+------------+----------+ | Fish bean bag toy | 3.49 | 3 | | Raggedy Ann | 4.99 | 1 | | 8 inch teddy bear | 5.99 | 1 | | 12 inch teddy bear | 8.99 | 1 | | King doll | 9.49 | 2 | | 18 inch teddy bear | 11.99 | 1 | +--------------------+------------+----------+ 6 rows in set (0.00 sec)
11-使用子查询：始终记得由内向外，由特殊到一般
mysql> SELECT order_num -> FROM orderitems -> WHERE prod_id='RGAN01'; +-----------+ | order_num | +-----------+ | 20007 | | 20008 | +-----------+ 2 rows in set (0.04 sec) mysql> SELECT cust_id -> FROM orders -> WHERE order_num IN (20007,20008); +------------+ | cust_id | +------------+ | 1000000004 | | 1000000005 | +------------+ 2 rows in set (0.02 sec) mysql> SELECT cust_id -> FROM orders -> WHERE order_num IN(SELECT order_num) -> ; +------------+ | cust_id | +------------+ | 1000000001 | | 1000000001 | | 1000000003 | | 1000000004 | | 1000000005 | +------------+ 5 rows in set (0.03 sec) mysql> SELECT cust_id -> FROM orders -> WHERE order_num IN(SELECT order_num -> FROM orderitems -> WHERE prod_id='RGAN01'); +------------+ | cust_id | +------------+ | 1000000004 | | 1000000005 | +------------+ 2 rows in set (0.00 sec) mysql> SELECT COUNT(*) -> FROM orders -> WHERE cust_id='1000000001'; +----------+ | COUNT(*) | +----------+ | 2 | +----------+ 1 row in set (0.00 sec) mysql> SELECT cust_name,cust_state, -> (SELECT COUNT(*) -> FROM orders -> WHERE orders.cust_id=customers.cust_id) AS orders -> FROM customers -> ORDER BY cust_name; +---------------+------------+--------+ | cust_name | cust_state | orders | +---------------+------------+--------+ | Fun4All | IN | 1 | | Fun4All | AZ | 1 | | Kids Place | OH | 0 | | The Toy Store | IL | 1 | | Village Toys | MI | 2 | +---------------+------------+--------+ 5 rows in set (0.00 sec) mysql> SELECT cust_name,cust_state, -> (SELECT COUNT(*) -> FROM orders -> WHERE cust_id=cust_id) AS orders -> FROM customers -> ORDER BY cust_name; +---------------+------------+--------+ | cust_name | cust_state | orders | +---------------+------------+--------+ | Fun4All | IN | 5 | | Fun4All | AZ | 5 | | Kids Place | OH | 5 | | The Toy Store | IL | 5 | | Village Toys | MI | 5 | +---------------+------------+--------+ 5 rows in set (0.00 sec)
12-联结表：注意和子查询的关系，INNER JOIN
mysql> SELECT vend_name,prod_name,prod_price -> FROM vendors,products -> WHERE vendors.vend_id=products.vend_id; +-----------------+---------------------+------------+ | vend_name | prod_name | prod_price | +-----------------+---------------------+------------+ | Bears R Us | 8 inch teddy bear | 5.99 | | Bears R Us | 12 inch teddy bear | 8.99 | | Bears R Us | 18 inch teddy bear | 11.99 | | Doll House Inc. | Fish bean bag toy | 3.49 | | Doll House Inc. | Bird bean bag toy | 3.49 | | Doll House Inc. | Rabbit bean bag toy | 3.49 | | Doll House Inc. | Raggedy Ann | 4.99 | | Fun and Games | King doll | 9.49 | | Fun and Games | Queen doll | 9.49 | +-----------------+---------------------+------------+ 9 rows in set (0.00 sec) mysql> SELECT vend_name,prod_name,prod_price -> FROM vendors,products; +-----------------+---------------------+------------+ | vend_name | prod_name | prod_price | +-----------------+---------------------+------------+ | Bear Emporium | Fish bean bag toy | 3.49 | | Bears R Us | Fish bean bag toy | 3.49 | | Doll House Inc. | Fish bean bag toy | 3.49 | | Fun and Games | Fish bean bag toy | 3.49 | | Furball Inc. | Fish bean bag toy | 3.49 | | Jouets et ours | Fish bean bag toy | 3.49 | | Bear Emporium | Bird bean bag toy | 3.49 | | Bears R Us | Bird bean bag toy | 3.49 | | Doll House Inc. | Bird bean bag toy | 3.49 | | Fun and Games | Bird bean bag toy | 3.49 | | Furball Inc. | Bird bean bag toy | 3.49 | | Jouets et ours | Bird bean bag toy | 3.49 | | Bear Emporium | Rabbit bean bag toy | 3.49 | | Bears R Us | Rabbit bean bag toy | 3.49 | | Doll House Inc. | Rabbit bean bag toy | 3.49 | | Fun and Games | Rabbit bean bag toy | 3.49 | | Furball Inc. | Rabbit bean bag toy | 3.49 | | Jouets et ours | Rabbit bean bag toy | 3.49 | | Bear Emporium | 8 inch teddy bear | 5.99 | | Bears R Us | 8 inch teddy bear | 5.99 | | Doll House Inc. | 8 inch teddy bear | 5.99 | | Fun and Games | 8 inch teddy bear | 5.99 | | Furball Inc. | 8 inch teddy bear | 5.99 | | Jouets et ours | 8 inch teddy bear | 5.99 | | Bear Emporium | 12 inch teddy bear | 8.99 | | Bears R Us | 12 inch teddy bear | 8.99 | | Doll House Inc. | 12 inch teddy bear | 8.99 | | Fun and Games | 12 inch teddy bear | 8.99 | | Furball Inc. | 12 inch teddy bear | 8.99 | | Jouets et ours | 12 inch teddy bear | 8.99 | | Bear Emporium | 18 inch teddy bear | 11.99 | | Bears R Us | 18 inch teddy bear | 11.99 | | Doll House Inc. | 18 inch teddy bear | 11.99 | | Fun and Games | 18 inch teddy bear | 11.99 | | Furball Inc. | 18 inch teddy bear | 11.99 | | Jouets et ours | 18 inch teddy bear | 11.99 | | Bear Emporium | Raggedy Ann | 4.99 | | Bears R Us | Raggedy Ann | 4.99 | | Doll House Inc. | Raggedy Ann | 4.99 | | Fun and Games | Raggedy Ann | 4.99 | | Furball Inc. | Raggedy Ann | 4.99 | | Jouets et ours | Raggedy Ann | 4.99 | | Bear Emporium | King doll | 9.49 | | Bears R Us | King doll | 9.49 | | Doll House Inc. | King doll | 9.49 | | Fun and Games | King doll | 9.49 | | Furball Inc. | King doll | 9.49 | | Jouets et ours | King doll | 9.49 | | Bear Emporium | Queen doll | 9.49 | | Bears R Us | Queen doll | 9.49 | | Doll House Inc. | Queen doll | 9.49 | | Fun and Games | Queen doll | 9.49 | | Furball Inc. | Queen doll | 9.49 | | Jouets et ours | Queen doll | 9.49 | +-----------------+---------------------+------------+ 54 rows in set (0.03 sec) mysql> SELECT vend_name,prod_name,prod_price -> FROM vendors INNER JOIN products -> ON vendors.vend_id=products.vend_id; +-----------------+---------------------+------------+ | vend_name | prod_name | prod_price | +-----------------+---------------------+------------+ | Bears R Us | 8 inch teddy bear | 5.99 | | Bears R Us | 12 inch teddy bear | 8.99 | | Bears R Us | 18 inch teddy bear | 11.99 | | Doll House Inc. | Fish bean bag toy | 3.49 | | Doll House Inc. | Bird bean bag toy | 3.49 | | Doll House Inc. | Rabbit bean bag toy | 3.49 | | Doll House Inc. | Raggedy Ann | 4.99 | | Fun and Games | King doll | 9.49 | | Fun and Games | Queen doll | 9.49 | +-----------------+---------------------+------------+ 9 rows in set (0.00 sec) mysql> SELECT cust_name,cust_contact -> FROM customers,orders,orderitems -> WHERE orders.cust_id=customers.cust_id -> AND orderitems.order_num=customers.order_num -> AND prod_id='RGAN01'; ERROR 1054 (42S22): Unknown column 'customers.order_num' in 'where clause' mysql> SELECT cust_name,cust_contact -> FROM customers,orders,orderitems -> WHERE orders.cust_id=customers.cust_id -> AND orderitems.order_num=orders.order_num -> AND prod_id='RGAN01'; +---------------+--------------------+ | cust_name | cust_contact | +---------------+--------------------+ | Fun4All | Denise L. Stephens | | The Toy Store | Kim Howard | +---------------+--------------------+ 2 rows in set (0.00 sec) mysql> SELECT cust_name,cust_contact -> FROM customers -> WHERE cust_id IN (SELECT cust_id -> FROM orders -> WHERE order_num IN (SELECT order_num -> FROM orderitems -> WHERE prod_id='RGAN01')); +---------------+--------------------+ | cust_name | cust_contact | +---------------+--------------------+ | Fun4All | Denise L. Stephens | | The Toy Store | Kim Howard | +---------------+--------------------+ 2 rows in set (0.00 sec)
13-高级联结：表别名（防止歧义），自联结，INNER JOIN,LEFT/RIGHT JOIN（需要那些没有关联行的行）（PS.MySQL中好像没有FULL OUTER JOIN和*=表示）
mysql> SELECT C.cust_id,C.cust_name,COUNT(*) -> FROM customers AS C,orders AS O -> WHERE C.cust_id=O.cust_id; +------------+--------------+----------+ | cust_id | cust_name | COUNT(*) | +------------+--------------+----------+ | 1000000001 | Village Toys | 5 | +------------+--------------+----------+ 1 row in set (0.02 sec) mysql> SELECT C.cust_id,C.cust_name,COUNT(*) -> FROM customers AS C,orders AS O -> WHERE C.cust_id=O.cust_id -> GROUP BY O.cust_name; ERROR 1054 (42S22): Unknown column 'O.cust_name' in 'group statement' mysql> SELECT C.cust_id,C.cust_name,COUNT(*) -> FROM customers AS C,orders AS O -> WHERE C.cust_id=O.cust_id -> GROUP BY O.cust_id; +------------+---------------+----------+ | cust_id | cust_name | COUNT(*) | +------------+---------------+----------+ | 1000000001 | Village Toys | 2 | | 1000000003 | Fun4All | 1 | | 1000000004 | Fun4All | 1 | | 1000000005 | The Toy Store | 1 | +------------+---------------+----------+ 4 rows in set (0.00 sec) mysql> SELECT prod_id,prod_name,COUNT(*) -> FROM products; +---------+-------------------+----------+ | prod_id | prod_name | COUNT(*) | +---------+-------------------+----------+ | BNBG01 | Fish bean bag toy | 9 | +---------+-------------------+----------+ 1 row in set (0.00 sec) mysql> SELECT prod_id,prod_name,COUNT(*) -> FROM products -> GROUP BY prod_name; +---------+---------------------+----------+ | prod_id | prod_name | COUNT(*) | +---------+---------------------+----------+ | BR02 | 12 inch teddy bear | 1 | | BR03 | 18 inch teddy bear | 1 | | BR01 | 8 inch teddy bear | 1 | | BNBG02 | Bird bean bag toy | 1 | | BNBG01 | Fish bean bag toy | 1 | | RYL01 | King doll | 1 | | RYL02 | Queen doll | 1 | | BNBG03 | Rabbit bean bag toy | 1 | | RGAN01 | Raggedy Ann | 1 | +---------+---------------------+----------+ 9 rows in set (0.00 sec) mysql> SELECT P.prod_id,P.prod_name,COUNT(*) -> FROM products,orderitems -> WHERE orderitems.prod_id=products.prod_id -> GROUP BY prod_name -> ORDER BY prod_id; ERROR 1054 (42S22): Unknown column 'P.prod_id' in 'field list' mysql> SELECT P.prod_id,P.prod_name,COUNT(*) -> FROM products AS P,orderitems AS O -> WHERE orderitems.prod_id=products.prod_id -> GROUP BY prod_name -> ORDER BY prod_id; ERROR 1054 (42S22): Unknown column 'orderitems.prod_id' in 'where clause' mysql> SELECT P.prod_id,P.prod_name,COUNT(*) -> FROM products AS P,orderitems AS O -> WHERE O.prod_id=P.prod_id -> GROUP BY P.prod_name -> ORDER BY P.prod_id; +---------+---------------------+----------+ | prod_id | prod_name | COUNT(*) | +---------+---------------------+----------+ | BNBG01 | Fish bean bag toy | 3 | | BNBG02 | Bird bean bag toy | 3 | | BNBG03 | Rabbit bean bag toy | 3 | | BR01 | 8 inch teddy bear | 2 | | BR02 | 12 inch teddy bear | 1 | | BR03 | 18 inch teddy bear | 4 | | RGAN01 | Raggedy Ann | 2 | +---------+---------------------+----------+ 7 rows in set (0.00 sec) mysql> SELECT P.prod_id,P.prod_name,SUM(O.quantity) -> FROM products AS P,orderitems AS O -> WHERE O.prod_id=P.prod_id -> GROUP BY P.prod_name -> ORDER BY P.prod_id; +---------+---------------------+-----------------+ | prod_id | prod_name | SUM(O.quantity) | +---------+---------------------+-----------------+ | BNBG01 | Fish bean bag toy | 360 | | BNBG02 | Bird bean bag toy | 360 | | BNBG03 | Rabbit bean bag toy | 360 | | BR01 | 8 inch teddy bear | 120 | | BR02 | 12 inch teddy bear | 10 | | BR03 | 18 inch teddy bear | 165 | | RGAN01 | Raggedy Ann | 55 | +---------+---------------------+-----------------+ 7 rows in set (0.00 sec) mysql> SELECT C.cust_id,O.order_num -> FROM customers AS C,orders AS O -> ; +------------+-----------+ | cust_id | order_num | +------------+-----------+ | 1000000001 | 20005 | | 1000000002 | 20005 | | 1000000003 | 20005 | | 1000000004 | 20005 | | 1000000005 | 20005 | | 1000000001 | 20009 | | 1000000002 | 20009 | | 1000000003 | 20009 | | 1000000004 | 20009 | | 1000000005 | 20009 | | 1000000001 | 20006 | | 1000000002 | 20006 | | 1000000003 | 20006 | | 1000000004 | 20006 | | 1000000005 | 20006 | | 1000000001 | 20007 | | 1000000002 | 20007 | | 1000000003 | 20007 | | 1000000004 | 20007 | | 1000000005 | 20007 | | 1000000001 | 20008 | | 1000000002 | 20008 | | 1000000003 | 20008 | | 1000000004 | 20008 | | 1000000005 | 20008 | +------------+-----------+ 25 rows in set (0.00 sec) mysql> SELECT C.cust_id,O.order_num -> FROM customers AS C LEFT OUTER JOIN orders AS O -> ON C.cust_id=O.cust_id; +------------+-----------+ | cust_id | order_num | +------------+-----------+ | 1000000001 | 20005 | | 1000000001 | 20009 | | 1000000002 | NULL | | 1000000003 | 20006 | | 1000000004 | 20007 | | 1000000005 | 20008 | +------------+-----------+ 6 rows in set (0.00 sec) mysql> SELECT C.cust_id,O.order_num -> FROM customers AS C RIGHT OUTER JOIN orders AS O -> ON C.cust_id=O.cust_id; +------------+-----------+ | cust_id | order_num | +------------+-----------+ | 1000000001 | 20005 | | 1000000001 | 20009 | | 1000000003 | 20006 | | 1000000004 | 20007 | | 1000000005 | 20008 | +------------+-----------+ 5 rows in set (0.00 sec) mysql> SELECT C.cust_id,O.cust_id -> FROM customers AS C,orders AS O -> WHERE C.cust_id *= O.cust_id; ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '= O.cust_id' at line 3 mysql> SELECT C.cust_id,O.order_num -> FROM customers AS C FULL OUTER JOIN orders AS O -> ON C.cust_id=O.cust_id; ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'FULL OUTER JOIN orders AS O ON C.cust_id=O.cust_id' at line 2 mysql> SELECT C.cust_id,O.order_num -> FROM customers AS C LEFT OUTER JOIN orders AS O -> ON C.cust_id=O.cust_id; +------------+-----------+ | cust_id | order_num | +------------+-----------+ | 1000000001 | 20005 | | 1000000001 | 20009 | | 1000000002 | NULL | | 1000000003 | 20006 | | 1000000004 | 20007 | | 1000000005 | 20008 | +------------+-----------+ 6 rows in set (0.00 sec) mysql> SELECT P.prod_id,P.prod_name,SUM(O.quantity) -> -> FROM products AS P,orderitems AS O -> -> WHERE O.prod_id=P.prod_id -> -> GROUP BY P.prod_name -> -> ORDER BY P.prod_id; ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '> FROM products AS P,orderitems AS O -> WHERE O.prod_id=P.prod_id -> GRO' at line 2 mysql> SELECT P.prod_id,P.prod_name,SUM(O.quantity) -> FROM products AS P LEFT OUTER JOIN orderitems AS O -> ON O.prod_id=P.prod_id -> GROUP BY P.prod_name -> ORDER BY P.prod_id; +---------+---------------------+-----------------+ | prod_id | prod_name | SUM(O.quantity) | +---------+---------------------+-----------------+ | BNBG01 | Fish bean bag toy | 360 | | BNBG02 | Bird bean bag toy | 360 | | BNBG03 | Rabbit bean bag toy | 360 | | BR01 | 8 inch teddy bear | 120 | | BR02 | 12 inch teddy bear | 10 | | BR03 | 18 inch teddy bear | 165 | | RGAN01 | Raggedy Ann | 55 | | RYL01 | King doll | NULL | | RYL02 | Queen doll | NULL | +---------+---------------------+-----------------+ 9 rows in set (0.00 sec)