ओरेकल में तीन टेबल

Question

मैं तीन टेबल है में शामिल होने के बाहरी छोड़ दिया नीचे दिखाया गया है जैसे:

और मैं नीचे की तरह उत्पादन प्राप्त करने के लिए कोशिश कर रहा हूँ:

यहाँ क्या है मैं अब तक कोशिश की है

SELECT table1.tb1_a, 
CASE WHEN table3.tb3_a IS NOT NULL THEN 
    tb3_b 
    ELSE 'No city for him yet' 
END AS 'City' 
FROM table1 
LEFT OUTER JOIN table2 ON 
    table1.tb1_a = table2.tb2_a 
LEFT OUTER JOIN table3 ON 
    table2.tb2_a = table3.tb3_a 
WHERE table3.tb3_a IN 
    (

    ) 

और अब मैं कैसे tb3_a स्तंभ का अधिकतम मान का चयन करने पर संघर्ष कर रहा हूँ

Answer 1

यह आपको क्या चाहिए करना चाहिए:

SELECT t1.tb1_a, COALESCE(t3.tb3_a, 'No city for him yet') AS City 
FROM table1 t1 
LEFT JOIN (
    SELECT MAX(tb2_b) AS tb2_b, tb2_a 
    FROM table2 
    GROUP BY tb2_a 
) t2 ON (t2.tb2_a = t1.tb1_a) 
LEFT JOIN table3 t3 ON (t3.tb3_a = t3.tb2_b); 

प्रमुख मुद्दा बीच में इन-लाइन दृश्य जहां हम आभासी का एक प्रकार बनाने है तालिका जिसमें प्रत्येक tb2_a के लिए अधिकतम tb2_b मान शामिल है। वांछित परिणाम प्राप्त करने के लिए हम इसमें शामिल हो सकते हैं।

Answer 2

कुछ इस तरह

select tb1_a, nvl(max(city), 'no city for him yet') thecity 
from etc 
group by tbl_a 

Answer 3

काम करना चाहिए मुझे लगता है कि आप विश्लेषणात्मक कार्यों के साथ ऐसा करना चाहते हैं।

SELECT tb1_a, coalesce(tb3_b, 'No city for him yet') as City 
from (select table1.tb1_a, tb3_b, 
      ROW_NUMBER() over (partition by table1.tbl1_a order by tb3_a desc) as seqnum 
     FROM table1 LEFT OUTER JOIN 
      table2 
      ON table1.tb1_a = table2.tb2_a LEFT OUTER JOIN 
      table3 
      ON table2.tb2_a = table3.tb3_a 
    ) t 
where seqnum = 1 

यह row_number() का उपयोग करता table3 में अंतिम प्रविष्टि निर्धारित करने के लिए: यहां बताया गया है। यह where seqnum = 1 खंड द्वारा चुना जाता है।

Answer 4

इस कोशिश, आशा है कि आप मदद

with table_1 as 
(select 10 as tb1_a, 'John' as tb1_b 
    from dual 
    union all 
    select 20 as tb1_a, 'John1' as tb1_b 
    from dual 
    union all 
    select 30 as tb1_a, 'John2' as tb1_b from dual), 
table_2 as 
(select 10 as tb2_a, 100 as tb2_b 
    from dual 
    union all 
    select 10 as tb2_a, 1000 as tb2_b 
    from dual 
    union all 
    select 10 as tb2_a, 10000 as tb2_b 
    from dual 
    union all 
    select 20 as tb2_a, 200 as tb2_b 
    from dual 
    union all 
    select 20 as tb2_a, 2000 as tb2_b 
    from dual 
    union all 
    select 20 as tb2_a, 20000 as tb2_b from dual), 
table_3 as 
(select 100 as tb3_a, 'City1' as tb3_b 
    from dual 
    union all 
    select 1000 as tb3_a, 'City10' as tb3_b 
    from dual 
    union all 
    select 10000 as tb3_a, 'City100' as tb3_b 
    from dual 
    union all 
    select 200 as tb3_a, 'City2' as tb3_b 
    from dual 
    union all 
    select 2000 as tb3_a, 'City20' as tb3_b 
    from dual 
    union all 
    select 20000 as tb3_a, 'City200' as tb3_b from dual) 

select user_id, city 
    from (select u.tb1_a as user_id, 
       nvl(c.tb3_b, 'No city') as city, 
       rank() over(partition by u.tb1_a order by tb3_a) as city_rank 
      from table_1 u, table_2 u_c, table_3 c 
     where u.tb1_a = u_c.tb2_a(+) 
      and u_c.tb2_b = c.tb3_a(+)) t1 
where city_rank = 1 

Answer 5

यह काम करता है:

http://sqlfiddle.com/#!4/7ba1c/12

SELECT table1.tb1_a, 
     CASE WHEN table3.tb3_a IS NOT NULL THEN tb3_b 
      ELSE 'No city for him yet' 
     END AS City, 
table2.*, table3.* 
FROM table1 
LEFT OUTER JOIN table2 ON table1.tb1_a = table2.tb2_a 
LEFT OUTER JOIN table3 ON table2.tb2_b = table3.tb3_a 
where tb2_b = (select max(tb2_b) 
       from table2 t22 
       where t22.tb2_a = tb1_a) 
or tb2_b is null 
order by 1 

मुझे लगता है कि जहां खंड ही बताते हैं