使用PHP和MySQL从多个表的多个列中选择DISTINCT

使用PHP和MySQL，我试图从下面列出的所有4个表的数字和类型列中获取所有不同的值：

table_1

ID|t1_number|t1_type
1|1|new
2|1|old
3|2|new
4|3|new
5|1|old

table_2

ID|t2_number|t2_type
1|1|future
2|1|new
3|3|past
4|3|new
5|1|new

table_3

ID|t3_number|t3_type
1|1|past
2|1|new
3|1|new
4|1|new
5|1|old

table_4

ID|t4_number|t4_type
1|1|new
2|4|new
3|3|old
4|2|new
5|1|new

我希望从上表中得到的值为：

数字：1,2,3,4

类型：新、旧、未来、过去

这是我到目前为止所拥有的；但我不确定SQL是否正确，也不确定如何格式化while循环以获取值

$sql = "SELECT DISTINCT table_1.t1_number, table_2.t2_number, table_3.t3_number, table_4.t4_number, table_1.t1_type, table_2.t2_type, table_3.t3_type, table_4.t4_type
FROM table_1 
JOIN table_2
JOIN table_3
JOIN table_4";

$result = @mysql_query($sql, $con) or die(mysql_error());

while($row = mysql_fetch_array($result)) {

    $numbers= $row[?????????];

}

使用SQL：

SELECT DISTINCT t1_number AS num FROM t1
    WHERE num NOT IN (SELECT t2_number FROM t2)
    AND num NOT IN (SELECT t3_number FROM t3)
    AND num NOT IN (SELECT t4_number FROM t4)

---

同样的想法也适用于这些类型。

你想要什么还不完全清楚。你想要四个不同的数字，然后是四个不同的类型吗

SELECT t1_number FROM table_1
UNION SELECT t2_number FROM table_2
UNION SELECT t3_number FROM table_3
UNION SELECT t4_number FROM table_4;

SELECT t1_type FROM table_1
UNION SELECT t2_type FROM table_2
UNION SELECT t3_type FROM table_3
UNION SELECT t4_type FROM table_4;

或者您想要每一对不同的数字和类型

SELECT t1_number, t1_type FROM table_1
UNION SELECT t2_number, t2_type FROM table_2
UNION SELECT t3_number, t3_type FROM table_3
UNION SELECT t4_number, t4_type FROM table_4;

---

UNION的一个优点是它隐式地将结果减少到不同的行。如果使用UNION ALL，则可以保留重复项。

在单个查询中执行此操作可能会在输出中复制数字或类型列的值，如果一个列表的值多于另一个列表的值。要为任一列获取不同的值列表，需要进行单独的查询：

数 类型

---

在这个联合查询中运行DISTINCT没有任何价值，因为重复项将被删除，而这只处理一列。

我想这就是您想要的：

select distinct number_value, type_value from (
  select t1_number as number_value, t1_type as type_value from table_1
union
  select t2_number as number_value, t2_type as type_value from table_2
union
  select t3_number as number_value, t3_type as type_value from table_3
union
  select t4_number as number_value, t4_type as type_value from table_4
)

---

@马克·拜尔斯：你的意思是他可以从规范化他的数据库中获益。@Bill Karwin:哦，是的，这就是我的意思。：）这将只返回来自

表1 t1的值；它不会有其他表中不存在的值，表1和表2的不同列号如何？
SELECT t1_type AS type
  FROM TABLE_1
UNION
SELECT t2_type
  FROM TABLE_2
UNION
SELECT t3_type
  FROM TABLE_3
UNION
SELECT t4_type
  FROM TABLE_4

select distinct number_value, type_value from (
  select t1_number as number_value, t1_type as type_value from table_1
union
  select t2_number as number_value, t2_type as type_value from table_2
union
  select t3_number as number_value, t3_type as type_value from table_3
union
  select t4_number as number_value, t4_type as type_value from table_4
)