Question

我对存储过程很陌生，但是我的项目需要形成一个复杂的存储过程。

逻辑上，我有一些想法，但不知道存储过程的确切语法和规则..

我需要循环遍历表的不同属性
distinct属性的每个值都会将另一个表的查询作为过滤条件

返回联盟表

alter procedure dbo.someStoreProcedure
    @paramA varchar(255)
    ....

    declare @attributeA,@resultSql 

    while( (select count distinct attributeA from tableA where attributeB>@paramA and attributeB<@paramA+5)>0)//1.

    BEGIN

    @attributeA=select count distinct attributeA from tableA where         attributeB>@paramA and attributeB<@paramA+5

    @resultSql=
        select fieldA,fieldB,fieldC from tableB where fieldB=@attributeA//2,within         loop
    UNION 
        select attributeA,attributeB,attributeC from table A where attributeB=@attributeA//3


    END

返回每个循环的（3）和（2）的联合结果

Answer 1

目标DBMS是什么？如果postgresql，我想我可以重写你的示例代码，如

    CREATE OR REPLACE FUNCTION dbo.someStoreProcedure(VARCHAR, VARCHAR) RETURNS SETOF RECORD AS '
    DECLARE
        paramA ALIAS FOR $1;
        paramB ALIAS FOR $2;
        resultSql RECORD;
        attributeA BIGINT;
    BEGIN
        WHILE ((SELECT COUNT(DISTINCT attributeA) FROM tableA WHERE attributeB > paramA AND attributeB < paramA + 5) > 0)
        LOOP
            attributeA := (SELECT COUNT(DISTINCT attributeA) FROM tableA WHERE attributeB > paramA AND attributeB < paramA + 5);
            FOR resultSql IN
                SELECT fieldA, fieldB, fieldC FROM tableB WHERE fieldB = attributeA
                UNION
                SELECT attributeA, attributeB, attribute C FROM tableA WHERE attributeB = attributeA
            LOOP
                RETURN NEXT resultSql;
            END LOOP;
        END LOOP;
        RETURN;
    END
' LANGUAGE pgplsql;

存储过程的语法

1 个答案: