Question

我有一种情况，我试图过滤那些有信用的人。这是一个Dapper查询示例供参考：

var sql = @"
    SELECT * 
    FROM Person 
    WHERE (Person.Credits > 0) = @hasCredits";

Connection.Query(sql, new { hasCredits });

我非常确定Postgres允许你这样做，因此当我在SQL Server上使用Incorrect syntax near '='失败时，我感到很惊讶。

使用下面的示例数据，我希望查询在hasCredits为FALSE时返回ID为1的Person，当hasCredits为TRUE时返回ID为2的Person。

INSERT INTO Person (PersonId, Credits) VALUES (1, 0), (2, 0);

在SQL Server中有没有办法评估表达式的计算结果是true还是false？

我考虑过以下（可怕的）选项，但希望有一个更优雅的解决方案：

"WHERE (Person.Credits " + (hasCredits ? ">" : "=") + " 0)"
"WHERE (@hasCredits = 1 AND Person.Credits > 0) OR (@hasCredits = 0 AND Person.Credits = 0)"

Answer 1

考虑到当Has credits单选按钮被选中时，@hasCredits变量将1当选择Doesn't have credits时@hasCredits变量将0变量@hasCredits其他null变量将为SELECT * FROM Person WHERE (Person.Credits > 0 and @hasCredits=1) or --Has credits (Person.Credits <1 and @hasCredits=0) or --Doesn't have credits (@hasCredits IS NULL) --Don't care

{{1}}

Answer 2

你的问题非常简单，答案非常简单！

case when Person.Credit > 0 then 1 else 0 end = @hasCredits

SQL Server中的[Expression] = TRUE / FALSE

2 个答案: