INFORMIX：来自不同 callid 和 Max 变量值的子查询的每个元素名的计数

Question

这是我的表格：

我需要为每个 callid 计算元素名的数量，其中 varname 等于 'eCounter' 且 varvalue 最大。

这些表是 elementid 一个（元素）到多个（elementdetail）的关系。我包含了实际 elementid 的格式，因此您不会假设它们是连续的数字。

我尝试了以下代码只是为了获得每个调用的最大值 varvalue/elementid，但这也没有成功。

SELECT MAX(a.varvalue) 作为 MAXvarvalue，b.callgui FROM elementdetail AS a，元素 AS b 其中 (a.elementid = b.elementid) 和 (a.varname = 'eCounter') GROUP BY varname, callguid

这就是我需要的结果。

Answer 1

使用最新的 Informix 版本 ( 14.10.XC1 )。

假设以下 tables:

CREATE TABLE element
(
    callid      INTEGER,
    elementid   BIGINT,
    elementname CHAR( 20 )
);

CREATE TABLE elementdetail
(
    elementid   BIGINT,
    varname     CHAR( 20 ),
    varvalue    INTEGER
);

其中填充了您的示例数据（OCR 来拯救，您真的应该 post 您的示例数据和 table 作为文本，而不是图像）：

INSERT INTO element VALUES ( 1, 1001901560322810000, 'set_Page1' );
INSERT INTO element VALUES ( 1, 1001921560322810000, 'set_Page5' );
INSERT INTO element VALUES ( 1, 1001181560322820000, 'set_Page4' );
INSERT INTO element VALUES ( 1, 1001021560322820000, 'set_Page3' );
INSERT INTO element VALUES ( 1, 1001331560322830000, 'set_Page6' );
INSERT INTO element VALUES ( 2, 1002281560322920000, 'set_Page1' );
INSERT INTO element VALUES ( 2, 1002301560322920000, 'set_Page5' );
INSERT INTO element VALUES ( 2, 1002881560322940000, 'set_Page4' );
INSERT INTO element VALUES ( 3, 1002271560322950000, 'set_Page1' );
INSERT INTO element VALUES ( 3, 1002951560322970000, 'set_Page4' );
INSERT INTO element VALUES ( 3, 1002231560322980000, 'set_Page6' );
INSERT INTO element VALUES ( 4, 1002781560323000000, 'set_Page1' );
INSERT INTO element VALUES ( 4, 1002891560323020000, 'set_Page5' );
INSERT INTO element VALUES ( 4, 1002391560323040000, 'set_Page4' );

INSERT INTO elementdetail VALUES ( 1001901560322810000, 'eCounter', 0 );
INSERT INTO elementdetail VALUES ( 1001901560322810000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1001921560322810000, 'eCounter', 1 );
INSERT INTO elementdetail VALUES ( 1001921560322810000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1001181560322820000, 'eCounter', 2 );
INSERT INTO elementdetail VALUES ( 1001181560322820000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1001021560322820000, 'eCounter', 4 );
INSERT INTO elementdetail VALUES ( 1001021560322820000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1001331560322830000, 'eCounter', 5 );
INSERT INTO elementdetail VALUES ( 1001331560322830000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002281560322920000, 'eCounter', 0 );
INSERT INTO elementdetail VALUES ( 1002281560322920000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002301560322920000, 'eCounter', 1 );
INSERT INTO elementdetail VALUES ( 1002301560322920000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002881560322940000, 'eCounter', 2 );
INSERT INTO elementdetail VALUES ( 1002881560322940000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002271560322950000, 'eCounter', 0 );
INSERT INTO elementdetail VALUES ( 1002271560322950000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002951560322970000, 'eCounter', 1 );
INSERT INTO elementdetail VALUES ( 1002951560322970000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002231560322980000, 'eCounter', 2 );
INSERT INTO elementdetail VALUES ( 1002231560322980000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002781560323000000, 'eCounter', 0 );
INSERT INTO elementdetail VALUES ( 1002781560323000000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002891560323020000, 'eCounter', 1 );
INSERT INTO elementdetail VALUES ( 1002891560323020000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002391560323040000, 'eCounter', 2 );
INSERT INTO elementdetail VALUES ( 1002391560323040000, 'other_variables', NULL );

我们可以做这样的事情，利用 CTE：

WITH cte_element AS
(
    SELECT
        e.callid,
        e.elementname,
        d.varvalue
    FROM
        element AS e
    INNER JOIN
        elementdetail AS d
    ON
        e.elementid = d.elementid
    WHERE
        d.varname = 'eCounter'
    ORDER BY
        e.callid,
        d.varvalue
) 
SELECT
    vt1.elementname,
    COUNT( vt1.elementname ) AS count_elementname
FROM
(
    SELECT
        tmp1.callid,
        tmp1.elementname,
        tmp1.varvalue
    FROM
        cte_element AS tmp1
    WHERE
        tmp1.varvalue = 
        (
            SELECT 
                MAX( tmp2.varvalue )
            FROM
                cte_element AS tmp2
            WHERE
                tmp1.callid = tmp2.callid
            GROUP BY
                tmp2.callid
        )
) AS vt1
GROUP BY
    vt1.elementname
;

-- Results
elementname          count_elementname

set_Page6                            2
set_Page4                            2

仍在使用最新版本的 Informix，使用窗口而不是 CTE：

SELECT
    vt1.elementname,
    COUNT( vt1.elementname ) AS count_elementname
FROM
(
SELECT
    e.callid,
    e.elementname,
    d.varvalue,
    RANK() OVER 
    ( 
        PARTITION BY e.callid ORDER BY e.callid, d.varvalue DESC 
    ) AS rank
FROM
    element AS e
INNER JOIN
    elementdetail AS d
ON
    e.elementid = d.elementid
WHERE
    d.varname = 'eCounter'
ORDER BY
    e.callid,
    d.varvalue
) AS vt1
WHERE
    vt1.rank = 1
GROUP BY
    vt1.elementname
;

-- Results
elementname          count_elementname

set_Page6                            2
set_Page4                            2

使用较旧的 Informix 版本，没有 CTE 或窗口，因此我们使用临时 table:

SELECT
    e.callid,
    e.elementname,
    d.varvalue
FROM
    element AS e
INNER JOIN
    elementdetail AS d
ON
    e.elementid = d.elementid
WHERE
    d.varname = 'eCounter'
ORDER BY
    e.callid,
    d.varvalue
INTO TEMP temp_element 
;

SELECT
    vt1.elementname,
    COUNT( vt1.elementname ) AS count_elementname
FROM
(
    SELECT
        tmp1.callid,
        tmp1.elementname,
        tmp1.varvalue
    FROM
        temp_element AS tmp1
    WHERE
        tmp1.varvalue = 
        (
            SELECT 
                MAX( tmp2.varvalue )
            FROM
                temp_element AS tmp2
            WHERE
                tmp1.callid = tmp2.callid
            GROUP BY
                tmp2.callid
        )
) AS vt1
GROUP BY
    vt1.elementname
;

-- Results
elementname          count_elementname

set_Page6                            2
set_Page4                            2

我不知道当您使用更强大的数据集（每个 table 上有数十万或数百万行）时，这些查询将如何扩展。

我没有测试过任何极端情况，例如，当 callid 有 2 个 elementname 具有相同的 eCounter varvalue 值时。

INFORMIX：来自不同 callid 和 Max 变量值的子查询的每个元素名的计数

INFORMIX: a count of each elementname from sub-query of distinct callid and the Max varable value

informix