Sql 表3优于表2，表2优于表1

我有3张桌子，上面有我几个朋友的名字和号码

表3有正确的数据，表2有微小的数据错误，表1有多于表2的数据错误

如果表2和表3中存在用户，则在output else表2 details中显示表3的详细信息；如果表2中甚至没有用户，则显示表1中的用户数据

更像是优先顺序

虚拟数据：

table 1 :

name phone
abc   2343
bcd   3434
ccd   3455
ffc   4545

table 2 :

name phone
abc   2313
bcd   3414
ccd   3415


table 3 :

name phone
abc   2344
bcd   3431

预期产出：

name phone
abc   2344
bcd   3431
ccd   3415
ffc   4545

我尝试了此查询，但找不到正确的输出

select phone,
    coalesce(table1.name, TABLE2.name,TABLE3.name) as namee
FROM   TABLE1
       left JOIN TABLE2 
               ON table1.name = table2.name
       INNER JOIN table3
               ON table3.name = table2.name

---

将是一个巨大的Heeelpppp。

使用

union all

：

select t1.*
from table1 t1
union all
select t2.*
from table2 t2
where not exists (select 1 from table1 t1 where t1.name = t2.name)
union all
select t3.*
from table3 t3
where not exists (select 1 from table1 t1 where t1.name = t3.name) and
      not exists (select 1 from table2 t2 where t2.name = t3.name);
  

---

戈登很接近；他有相反的偏好。请确保您理解脚本工作的原因

-- grab all our preferred data first
select t3.*
from table3 t3

union all

-- grab anything that doesn't exist in our preferred table
select t2.*
from table2 t2
where not exists (select 1 from table3 t3 where t3.name = t2.name)

union all

-- grab anything that doesn't exist in our preferred tables
select t1.*
from table1 t1
where not exists (select 1 from table2 t2 where t2.name = t1.name) and
      not exists (select 1 from table3 t3 where t3.name = t1.name);

---

给出错误的输出，我从表1而不是表3得到“abc”，从表2而不是表3得到“bcd”3@yono . . . 如果您的顺序是表1-->表3-->表2，则只需交换表名即可。