id type name
1 E AA
2 F
表B
id Aid name
1 2 BB
2 2 CC
表B 是表A的子表
如果表A中的type是F，就需要根據Aid 去表B裏找對應的name，然後拼接起來
數據庫是Oracle10G 需要查詢的結果：
Aid type name
1 E AA
2 F BB,CC
*********************************************************
WITH TABLE1 AS(
SELECT '1' AS Aid, 'E' AS type,'AA' as name FROM dual
union all
SELECT '2' AS Aid, 'F' AS type,'' as name FROM dual
union all
SELECT '3' AS Aid, 'F' AS type,'' as name FROM dual
union all
SELECT '4' AS Aid, 'A' AS type,'FF' as name FROM dual
),
TABLE2 AS (
SELECT '1' AS id, '2' AS Aid,'BB' as name FROM dual
union all
SELECT '2' AS id, '2' AS Aid,'CC' as name FROM dual
union all
SELECT '3' AS id, '3' AS Aid,'DD' as name FROM dual
union all
SELECT '4' AS id, '3' AS Aid,'EE' as name FROM dual
)
SELECT T1.Aid,
T1.TYPE,
LISTAGG(nvl(T1.NAME, T2.NAME),',')WITHIN GROUP(ORDER BY id) AS NAME
FROM TABLE1 T1
LEFT JOIN TABLE2 T2 ON T1.Aid = T2.Aid
GROUP BY T1.Aid, T1.TYPE
由於查詢的字段很多 能否不用 【GROUP BY】
用函數實現也可以
SELECT T1.NAME || T2.NAME
AS NAME ,T1.* FROM TABLE1 T1 LEFT JOIN (SELECT Aid,LISTAGG(NAME, ',') WITHIN
GROUP(
ORDER BY id) AS NAME FROM TABLE2 GROUP BY Aid) T2 ON T1.Aid = T2.Aid ORDER BY T1.Aid