动态更改SQL查询中的where子句

Question

我在需要调用.net核心API并返回结果的地方构建Angular应用程序。 如下所示，角度应用中有两个字段

可以选择两个字段，可能只是一个字段将被选择，并且需要根据选择从API获取结果

如果两个字段都被选中，我的查询如下

  Select prj_number,location from sTable where r_proj = '000634' AND sdate = '2019-07-01' group by prj_number,location

如果只是选择了报告项目，那么

 Select prj_number,location from sTable where r_proj = '000634'  group by prj_number,location

同样，对于持续时间，根据Angular的选择动态更改where子句。

我想根据像这样的选择在Angular中构建一个字符串表达式

     string para = r_proj = '000634' AND sdate = '2019-07-01' 

并像这样传递给查询

  Select prj_number,location from sTable where @para  group by prj_number,location

但这没有用，我收到类似'An expression of non-boolean type specified in a context where a condition is expected, near 'group'.'类'An expression of non-boolean type specified in a context where a condition is expected, near 'group'.'错误'An expression of non-boolean type specified in a context where a condition is expected, near 'group'.' 看起来我无法传递表达式作为参数。 我如何应对这种情况

Answer 1

将每个参数设置为“可选”，如下所示：

DECLARE @projIdFilter varchar(10) = null
DECLARE @sdateFilter datetime = null

SELECT prj_number,location 
FROM sTable 
WHERE (@projIdFilter is null or r_proj = @projIdFilter) -- parenthesis are important
  AND (@sdateFilter is null or sdate = @sdateFilter)
GROUP BY prj_number,location