关于tsql：如何在T-SQL存储过程中使用可选参数？

How can I use optional parameters in a T-SQL stored procedure?

我正在创建一个存储过程来搜索表。我有许多不同的搜索字段，它们都是可选的。是否有方法创建将处理此问题的存储过程？假设我有一个表，有四个字段：id、firstname、lastname和title。我可以这样做：

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CREATE PROCEDURE spDoSearch
@FirstName varchar(25) = null,
@LastName varchar(25) = null,
@Title varchar(25) = null
AS
BEGIN
SELECT ID, FirstName, LastName, Title
FROM tblUsers
WHERE
FirstName = ISNULL(@FirstName, FirstName) AND
LastName = ISNULL(@LastName, LastName) AND
Title = ISNULL(@Title, Title)
END

这类作品。但是，它忽略firstname、lastname或title为空的记录。如果搜索参数中未指定标题，我希望包括标题为空的记录-firstname和lastname的标题相同。我知道我可以用动态SQL来实现这一点，但我想避免这种情况。

相关讨论

@km的回答是很好的，但没有完全跟进他早期的建议之一；

..., ignore compact code, ignore worrying about repeating code, ...

如果您希望获得最佳性能，那么应该为可选条件的每个可能组合编写一个定制查询。这听起来可能很极端，如果您有很多可选的标准，那么它可能是，但是性能通常是工作和结果之间的权衡。在实践中，可能会有一组通用的参数组合，这些参数组合可以以定制查询为目标，然后是所有其他组合的通用查询(根据其他答案)。

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CREATE PROCEDURE spDoSearch
@FirstName varchar(25) = null,
@LastName varchar(25) = null,
@Title varchar(25) = null
AS
BEGIN

IF (@FirstName IS NOT NULL AND @LastName IS NULL AND @Title IS NULL)
-- Search by first name only
SELECT ID, FirstName, LastName, Title
FROM tblUsers
WHERE
FirstName = @FirstName

ELSE IF (@FirstName IS NULL AND @LastName IS NOT NULL AND @Title IS NULL)
-- Search by last name only
SELECT ID, FirstName, LastName, Title
FROM tblUsers
WHERE
LastName = @LastName

ELSE IF (@FirstName IS NULL AND @LastName IS NULL AND @Title IS NOT NULL)
-- Search by title only
SELECT ID, FirstName, LastName, Title
FROM tblUsers
WHERE
Title = @Title

ELSE IF (@FirstName IS NOT NULL AND @LastName IS NOT NULL AND @Title IS NULL)
-- Search by first and last name
SELECT ID, FirstName, LastName, Title
FROM tblUsers
WHERE
FirstName = @FirstName
AND LastName = @LastName

ELSE
-- Search by any other combination
SELECT ID, FirstName, LastName, Title
FROM tblUsers
WHERE
(@FirstName IS NULL OR (FirstName = @FirstName))
AND (@LastName IS NULL OR (LastName = @LastName ))
AND (@Title IS NULL OR (Title = @Title ))

END

这种方法的优点是，在由定制查询处理的常见情况下，查询的效率尽可能高——不受不适用条件的影响。此外，索引和其他性能增强可以针对特定的定制查询，而不是试图满足所有可能的情况。

相关讨论

在以下情况下可以这样做，

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CREATE PROCEDURE spDoSearch
@FirstName varchar(25) = null,
@LastName varchar(25) = null,
@Title varchar(25) = null
AS
BEGIN
SELECT ID, FirstName, LastName, Title
FROM tblUsers
WHERE
(@FirstName IS NULL OR FirstName = @FirstName) AND
(@LastNameName IS NULL OR LastName = @LastName) AND
(@Title IS NULL OR Title = @Title)
END

但是依赖于数据有时更好地创建动态查询并执行它们。

延长你的WHERE条件：

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WHERE
(FirstName = ISNULL(@FirstName, FirstName)
OR COALESCE(@FirstName, FirstName, '') = '')
AND (LastName = ISNULL(@LastName, LastName)
OR COALESCE(@LastName, LastName, '') = '')
AND (Title = ISNULL(@Title, Title)
OR COALESCE(@Title, Title, '') = '')

也就是说，将不同的情况与布尔条件结合起来。

晚会迟到了五年。

在已接受答案的提供链接中提到了这个问题，但是我认为它应该得到一个明确的答案，因为它基于所提供的参数动态地构建查询。例如。：

安装程序

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-- drop table Person
create table Person
(
PersonId INT NOT NULL IDENTITY(1, 1) CONSTRAINT PK_Person PRIMARY KEY,
FirstName NVARCHAR(64) NOT NULL,
LastName NVARCHAR(64) NOT NULL,
Title NVARCHAR(64) NULL
)
GO

INSERT INTO Person (FirstName, LastName, Title)
VALUES ('Dick', 'Ormsby', 'Mr'), ('Serena', 'Kroeger', 'Ms'),
('Marina', 'Losoya', 'Mrs'), ('Shakita', 'Grate', 'Ms'),
('Bethann', 'Zellner', 'Ms'), ('Dexter', 'Shaw', 'Mr'),
('Zona', 'Halligan', 'Ms'), ('Fiona', 'Cassity', 'Ms'),
('Sherron', 'Janowski', 'Ms'), ('Melinda', 'Cormier', 'Ms')
GO

程序

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ALTER PROCEDURE spDoSearch
@FirstName varchar(64) = null,
@LastName varchar(64) = null,
@Title varchar(64) = null,
@TopCount INT = 100
AS
BEGIN
DECLARE @SQL NVARCHAR(4000) = '
SELECT TOP ' + CAST(@TopCount AS VARCHAR) + ' *
FROM Person
WHERE 1 = 1'

PRINT @SQL

IF (@FirstName IS NOT NULL) SET @SQL = @SQL + ' AND FirstName = @FirstName'
IF (@LastName IS NOT NULL) SET @SQL = @SQL + ' AND FirstName = @LastName'
IF (@Title IS NOT NULL) SET @SQL = @SQL + ' AND Title = @Title'

EXEC sp_executesql @SQL, N'@TopCount INT, @FirstName varchar(25), @LastName varchar(25), @Title varchar(64)',
@TopCount, @FirstName, @LastName, @Title
END
GO

用法

1 2	exec spDoSearch @TopCount = 3 exec spDoSearch @FirstName = 'Dick'

赞成的意见：

易于书写和理解
灵活性-很容易生成有关细流过滤的查询(例如动态顶部)

欺骗：

可能的性能问题取决于提供的参数、索引和数据量

不是直接的答案，而是与问题有关，也就是说，大问题。

通常，这些筛选存储过程不会四处浮动，而是从某个服务层调用。这就留下了将业务逻辑(过滤)从SQL移到服务层的选项。

一个例子是使用linq2sql根据提供的过滤器生成查询：

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public IList<SomeServiceModel> GetServiceModels(CustomFilter filters)
{
var query = DataAccess.SomeRepository.AllNoTracking;

// partial and insensitive search
if (!string.IsNullOrWhiteSpace(filters.SomeName))
query = query.Where(item => item.SomeName.IndexOf(filters.SomeName, StringComparison.OrdinalIgnoreCase) != -1);
// filter by multiple selection
if ((filters.CreatedByList?.Count ?? 0) > 0)
query = query.Where(item => filters.CreatedByList.Contains(item.CreatedById));
if (filters.EnabledOnly)
query = query.Where(item => item.IsEnabled);

var modelList = query.ToList();
var serviceModelList = MappingService.MapEx<SomeDataModel, SomeServiceModel>(modelList);
return serviceModelList;
}

赞成的意见：

基于提供的过滤器动态生成的查询。不需要参数嗅探或重新编译提示
为那些在OOP世界里的人写东西比较容易
通常性能友好，因为将发出"简单"查询(但仍然需要适当的索引)

欺骗：

可能会达到linq2ql限制，并根据情况强制降级到linq2objects或返回纯SQL解决方案
不小心编写LINQ可能会生成糟糕的查询(如果加载了导航属性，则可能会生成许多查询)

这也适用于：

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...
WHERE
(FirstName IS NULL OR FirstName = ISNULL(@FirstName, FirstName)) AND
(LastName IS NULL OR LastName = ISNULL(@LastName, LastName)) AND
(Title IS NULL OR Title = ISNULL(@Title, Title))