在表中合併多個記錄到一個領域中基於領域的第三個表

Question

另一個表我有三個表：

Table 1: 
pid, name, address 
1 Dale BLANK 

Table 2: 
pid, moid 
1 12 

Table 3: 
moid, address 
12 123 Main 
12 12 South 
12 99 North 

對於輸出我需要：

Table 1: 
pid, name, address 
1 Dawn 123 Mian,12 South,99 North 

我如何可以結合將表3中的多個地址轉換爲表1中的一個地址字段，將兩個表與表2中的信息鏈接起來？

Answer 1

您沒有指定您正在使用的RDBMS。在MySQL中，你可以使用GROUP_CONCAT()：

select t1.pid, 
    t1.name, 
    group_concat(t3.address) Address 
from table1 t1 
left join table2 t2 
    on t1.pid = t2.pid 
left join table3 t3 
    on t2.moid = t3.moid 
group by t1.pid, t1.name 

見SQL Fiddle with Demo

編輯＃1，如果你想UPDATE表這個結果，那麼UPDATE聲明將是這樣的：

update table1 t1 
set address = (SELECT group_concat(t3.address) 
       FROM table2 t2 
       left join table3 t3 
       on t2.moid = t3.moid 
       where t1.pid = t2.pid 
       group by t1.pid, t1.name); 

見SQL Fiddle with Demo

如果喲u的使用Oracle 11g +，那麼你可以使用 ListAgg()功能：

select t1.pid, 
    t1.name, 
    listagg(t3.address, ', ') WITHIN GROUP (ORDER BY t1.pid) Address 
from table1 t1 
left join table2 t2 
    on t1.pid = t2.pid 
left join table3 t3 
    on t2.moid = t3.moid 
group by t1.pid, t1.name 

見SQL Fiddle with Demo

在SQL Server，你可以使用FOR XML PATH得到結果：

select t1.pid, 
    t1.name, 
    STUFF((SELECT DISTINCT ', '+ t3.address 
     FROM table3 t3 
     LEFT JOIN table2 t2 
      ON t2.moid = t3.moid 
     WHERE t1.pid = t2.pid 
     FOR XML PATH('')), 1, 1, '') Address 
from table1 t1 
group by t1.pid, t1.name 

見 SQL Fiddle with Demo

所有這些產生的結果：

| PID | NAME |     ADDRESS | 
------------------------------------------- 
| 1 | Dale | 12 South,99 North,123 Main | 

Answer 2

爲此，您可以加入：

select table1.pid, table1.name, 
     group_concat(table3.address, ', ') 
from table2 join 
    table1 
    on table2.pid = table1.pid join 
    table3 
    on table2.moid = table3.moid 
gorup by table1.pid 

功能group_concat不存在於所有數據庫。 。 。其他字符串聚合功能是listagg和ws_concat。希望你沒有使用SQL Server，因爲字符串串聯更難。