Question

我正在尝试创建一个返回表的所有列名称的查询，并且每个列的计数都不同。我有超过1400个表进行测试，其中一些有100列，所以我无法想象逐个列出colomn名称。
我对计数部分有问题，而且我想知道是否可以在子查询中执行类似EXECUTE IMMEDIATE的操作，如果没有，是否还有其他解决方案？

这是我的实际查询：

SELECT 
    sc.name AS columnName
    , ('SELECT COUNT(DISTINCT ' || sc.name || ') FROM MyTableName') AS nb_distinct_row  
FROM dbo.syscolumns sc INNER JOIN sysobjects so 
    ON so.id = sc.id 
    AND so.name = 'MyTableName'
GROUP BY sc.name

这会返回好的子查询，但我不知道如何立即执行它？我尝试过像

这样的东西

, (SELECT count(distinct sc.name) from MyTableName) As nbDistinctRow

但是'sc.name'没有被解释，并且count distinct返回1，所以这就是我尝试这种方式的原因。

我在sybase IQ数据库上工作

任何人都可以帮助我吗？提前谢谢你。

Answer 1

我找到了一种方法来完成这项工作，但它确实很笨拙。

CREATE OR REPLACE PROCEDURE FLA_distinctCols(in table_obj_id INT)
RESULT (column_name VARCHAR(128), count_distinct INT)
BEGIN
    DECLARE err_notfound EXCEPTION FOR SQLSTATE VALUE '02000';
    DECLARE @tablename VARCHAR(100);
    DECLARE @cols      VARCHAR(128);
    DECLARE @nb_dist   INT;
    DECLARE @sql       VARCHAR(30000);
    DECLARE @sqltemp       VARCHAR(30000);

DECLARE tables NO SCROLL CURSOR FOR
    SELECT 
        sc.name col
        , ('SELECT COUNT(DISTINCT ' || sc.name || ') INTO @nb_dist FROM ' || @tablename) 
    FROM dbo.syscolumns sc INNER JOIN sysobjects so 
        ON so.id = sc.id 
        AND so.name = @tablename 
         || '%' ORDER BY sc.name
;


SELECT so.name INTO @tablename FROM sysobjects so WHERE so.id = table_obj_id;

create table #tablestats (
    column_name       varchar(128) not null,
    count_distinct       INT,
);

open tables WITH HOLD;

LoopTables: loop

    fetch next tables into @cols, @sqltemp;

    if sqlstate = err_notfound then
        leave LoopTables
    else
        EXECUTE IMMEDIATE WITH QUOTES @sqltemp;
        set @sql= 'INSERT INTO #tablestats SELECT ''' || @cols || ''', ' || @nb_dist || ';';
        EXECUTE IMMEDIATE WITH QUOTES @sql;
    end if

end loop LoopTables;

close tables;

SELECT column_name, count_distinct FROM #tablestats ORDER BY count_distinct DESC;

END


GO
BEGIN 
    DECLARE @tablename VARCHAR(128);
    DECLARE @tableid INT;
    SET @tablename = 'Mytablename';
    SELECT so.id INTO @tableid FROM sysobjects so WHERE so.name = @tablename;

    SELECT * FROM FLA_distinctCols(@tableid);

END

还有其他解决方案吗？

Sybase：在子查询上执行IMMEDIATE

1 个答案: