如何獲得每行固定數量的結果？

Question

如何使用sqlite3數據庫以這種格式構建查詢？

CREATE TABLE sample (integer foo); 
INSERT INTO sample VALUES (1); 
... 
INSERT INTO sample VALUES (10); 

格式結果

1,2,3 
4,5,6 
7,8,9 
10 

Answer 1

您將有一些標準添加到組的他們：

CREATE TABLE sample (integer foo, char(1) bar); 
INSERT INTO sample VALUES 
(1, 'a'), (2, 'a'), (3, 'a'), (4, 'b'), (5, 'b'), (6, 'b'), (7, 'c') ...; 

SELECT GROUP_CONCAT(foo ORDER BY foo, ',') 
FROM sample 
GROUP BY bar 

編輯：

試試這個：

select group_concat(foo) from (
    select s1.foo, (count(*) - 1)/3 grp from sample s1 
    join sample s2 on s1.rowid >= s2.rowid 
    group by s1.rowid 
) final 
group by grp 

Answer 2

這可能不是最好的解決辦法（並具有一定優勢的情況下---如果你有一個3值不爲空），並且大概可以放入一個查詢中，但我需要RowId加入。它應該做的伎倆，雖然：

CREATE TEMP TABLE split1 (foo1 int); 
CREATE TEMP TABLE split2 (foo2 int); 
CREATE TEMP TABLE split3 (foo3 int); 

INSERT INTO split1 
SELECT foo FROM sample WHERE foo % 3 = 1 ORDER BY foo 

INSERT INTO split2 
SELECT foo FROM sample WHERE foo % 3 = 2 ORDER BY foo 

INSERT INTO split3 
SELECT foo FROM sample WHERE foo % 3 = 0 ORDER BY foo 

SELECT 
    CASE 
     WHEN foo2 IS NULL THEN foo1 
     WHEN foo3 IS NULL THEN foo1||','||foo2 
     ELSE foo1||','||foo2||','||foo3 
    END 
FROM split1 
    LEFT JOIN split2 
     ON split1.RowId = split2.RowId 
    LEFT JOIN split3 
     ON split2.RowId = split3.RowId