mysql - 谁能教我连接表的 SQL

Question

我有以下表格：

表 1 表 2
id q_id 内容id | w_id | q_id | c_id | 排行
---------------------- ---------------------------- --------------------
95 2046 1=E 123 | 22404 | 2046 | 100 | 1

96 2046 2=G 124 | 22404 | 2046 | 101 | 2

97 2046 3=N 125 | 22404 | 2046 | 102 | 2

98 2046 4=B 126 | 22404 | 2046 | 103 | 2

99 2046 5=V 127 | 22404 | 2046 | 104 | 3

100 2046 A1 128 | 22404 | 2046 | 105 | 3

101 2046 A2 129 | 22405 | 2046 | 100 | 4

102 2046 A3 130 | 22405 | 2046 | 101 | 4

103 2046 A4 131 | 22405 | 2046 | 102 | 1

104 2046 A5 132 | 22405 | 2046 | 103 | 2

105 2046 A6 133 | 22405 | 2046 | 104 | 2

                                    134 | 22405 | 2046 | 105 | 3

我需要编写一个 SQL，这样我才能得到以下结果：

w_id  | q_id  | A1  | A2  | A3  | A4  | A5  | A6 
--------------------------------------------------- 
22404 | 2046  |  1  |  2  |  2  |  2  |  3  |  3  
22405 | 2046  |  4  |  4  |  1  |  2  |  2  |  3  

谁能帮我？

Answer 1

无需加入这些表。

你可能需要这样的东西：

SELECT w_id as W , q_id, 
(select ranking from table2 where w_id = W and c_id = 100) as 100,
(select ranking from table2 where w_id = W and c_id = 101) as 101,
(select ranking from table2 where w_id = W and c_id = 102) as 102,
(select ranking from table2 where w_id = W and c_id = 103) as 103,
(select ranking from table2 where w_id = W and c_id = 104) as 104,
(select ranking from table2 where w_id = W and c_id = 105) as 105
FROM table2;