Mysql_嵌套表查詢_查詢結果作爲子表（臨時表

此功能同Oracle一樣！

 

    許多人都覺得MySQL不支持嵌套查詢，其實MySQl從4.11版後已經完全支持嵌套查詢了，那麼下面我舉些簡單的嵌套查詢的例子吧（源程序來自MySQL User Manual）：

    1. SELECT語句的子查詢:
    語法: （注意：AS 可省略）
 例如：

SELECT sb1,sb2,sb3
       FROM (SELECT s1 AS sb1, s2 AS sb2, s3*2 AS sb3 FROM t1) AS sb
       WHERE sb1 > 1;

CODE:
SELECT AVG(sum_column1)        FROM (SELECT SUM(column1) AS sum_column1              FROM t1 GROUP BY column1) AS t1;

 

.2.行的子查詢（Row Subquery）：

CODE:
SELECT * FROM t1 WHERE ROW(1,2) = (SELECT column1, column2 FROM t2);

3.使用Exist和Not Exist參數
    這裏的Exist和Not Exist用途及用法和在其他沒有什麼大的區別,我就簡單舉幾個範例好了:

CODE:
SELECT DISTINCT store_type FROM Stores                     WHERE EXISTS (SELECT * FROM Cities_Stores                                   WHERE Cities_Stores.store_type = Stores.store_type);

 

 

  CODE:    
SELECT DISTINCT store_type FROM Stores
                       WHERE NOT EXISTS (SELECT * FROM Cities_Stores
                                   WHERE Cities_Stores.store_type = Stores.store_type);

 

參考博客：https://blog.csdn.net/fantaxy025025/article/details/83848674