MYSQL選擇和組如果列值

Question

我有一個MYSQL表 - - 爲了簡化它 - 三欄：名稱，地址和主要住所。

可以有重複名稱的行。我想做一個選擇語句來返回一個人的姓名和地址。如果他們在表格中兩次，這意味着他們有兩個地址。但是，如果其中一個是「主要住宅」，我希望它只返回主要住宅。否則，它應該返回兩個地址。 謝謝！

表：

Name | Address | Primary Residence 
John Smith | 123 Main Str | Yes 
John Smith | 456 June Str | 
Mike Dore | 893 West St | 
Jake John | 999 East St | 
Jake John | 145 South St | 

返回：

Name | Address 
John Smith | 123 Main Str 
Mike Dore | 893 West St 
Jake John | 999 East St 
Jake John | 145 South St 

Answer 1

這裏有一種方法......

CREATE TABLE addresses 
(Name VARCHAR(20) NOT NULL 
,Address VARCHAR(20) NOT NULL 
,is_primary TINYINT NULL 
,PRIMARY KEY (name,address) 
); 

INSERT INTO addresses VALUES 
('John Smith','123 Main Str',1), 
('John Smith','456 June Str',NULL), 
('Mike Dore','893 West St',NULL), 
('Jake John','999 East St',NULL), 
('Jake John','145 South St',NULL); 


SELECT * FROM addresses; 
+------------+--------------+------------+ 
| Name  | Address  | is_primary | 
+------------+--------------+------------+ 
| Jake John | 145 South St |  NULL | 
| Jake John | 999 East St |  NULL | 
| John Smith | 123 Main Str |   1 | 
| John Smith | 456 June Str |  NULL | 
| Mike Dore | 893 West St |  NULL | 
+------------+--------------+------------+ 

SELECT DISTINCT x.name 
       , COALESCE(y.address,x.address) address 
      FROM addresses x 
      LEFT 
      JOIN addresses y 
      ON y.name = x.name 
      AND y.is_primary = 1; 
+------------+--------------+ 
| name  | address  | 
+------------+--------------+ 
| Jake John | 145 South St | 
| Jake John | 999 East St | 
| John Smith | 123 Main Str | 
| Mike Dore | 893 West St | 
+------------+--------------+ 

Answer 2

它可能與子查詢來完成。

select * from TBL where NAME not in (select NAME from TBL where residence='PRI') 
union 
select * from TBL where residence='PRI'; 

編輯： AFTER問題UPDATE：

select * from TBL where NAME not in (select NAME from TBL where residence='yes') 
union 
select * from TBL where residence='yes' 

http://sqlfiddle.com/#!2/39493/5/0