有条件地修改SQL查询 [英] Conditionally modify SQL query

问题描述

我有一个sql查询，比如下面的表格：

从表t中选择a，b，c，其中ta =hello和tb =there和tc =world group by a，b，c

我想要一个布尔条件（d == true）来确定上面的计算，这样当d设置为true时，执行上面的查询，当d为false时，查询将缩减为以下内容并编译：

从表t中选择a，b，其中ta =hello，tb =theregroup by a，b。



关于如何使用oracle 11g（sql / pl-sql / t-sql）实现这一点的任何建议？



我尝试了什么：



我尝试过设置标志和执行查询的简单逻辑，但我需要根据预设条件有条件地编译部分查询。

I have a sql query, say of the following form:
select a, b, c from table t where t.a = "hello" and t.b = "there" and t.c = "world" group by a,b,c
I would like to have a Boolean condition (d == true) to determine the computation above such that when say d is set to true, the above query get executed, and when d is false, the query gets reduced to the following and compiled:
select a, b from table t where t.a = "hello" and t.b = "there" group by a,b.

Any suggestions as to how this could be achieved using oracle 11g (sql/pl-sql/t-sql)?

What I have tried:

I have tried a simple logic of setting the flag and executing the query but I need to conditionally compile part of the query based on a preset condition.

推荐答案

你可以将case放在group by中。检查 - SQL查询中的动态和条件分组 - 从单个查询获得灵活的结果（哦和CUBE运算符的有用情况） - AMIS Oracle和Java Blog [ ^ ]。

You can put case in group by. Check - Dynamic and Conditional grouping in SQL queries - for flexible results from single query (oh and a useful case for the CUBE operator) - AMIS Oracle and Java Blog[^].

这篇关于有条件地修改SQL查询的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！