是否有可能在mssql的WHERE子句中使用IF子句?
例子:
WHERE
IF IsNumeric(@OrderNumber) = 1
OrderNumber = @OrderNumber
ELSE
OrderNumber LIKE '%' + @OrderNumber + '%'
是否有可能在mssql的WHERE子句中使用IF子句?
例子:
WHERE
IF IsNumeric(@OrderNumber) = 1
OrderNumber = @OrderNumber
ELSE
OrderNumber LIKE '%' + @OrderNumber + '%'
当前回答
我认为在……情况下……可以使用布尔值。我正在使用T-SQL。
场景:假设如果bool为假,你想获取Person-30的爱好,如果bool为真,你想获取Person-42的爱好。(根据一些人的说法,业余爱好查找占了90%以上的商业计算周期,所以要密切关注。)
CREATE PROCEDURE sp_Case
@bool bit
AS
SELECT Person.Hobbies
FROM Person
WHERE Person.ID =
case @bool
when 0
then 30
when 1
then 42
end;
其他回答
//使用存储过程按国家和站点筛选用户的示例
CREATE STORED PROCEDURE GetUsers
@CountryId int = null,
@SiteId int = null
AS
BEGIN
SELECT *
FROM Users
WHERE
CountryId = CASE WHEN ISNUMERIC(@CountryId) = 1 THEN @CountryId ELSE CountryId END AND
SiteId = CASE WHEN ISNUMERIC(@SiteId) = 1 THEN @SiteId ELSE SiteId END END
//从输入的countryId和/或siteId如果存在,否则不过滤
使用CASE语句 更新:之前的语法(正如一些人指出的那样)不起作用。CASE的用法如下:
WHERE OrderNumber LIKE
CASE WHEN IsNumeric(@OrderNumber) = 1 THEN
@OrderNumber
ELSE
'%' + @OrderNumber
END
或者你可以使用一个IF语句,比如@N。里德指出。
CASE语句总是比IF语句更好的选择。
WHERE vfl.CreatedDate >= CASE WHEN @FromDate IS NULL THEN vfl.CreatedDate ELSE @FromDate END
AND vfl.CreatedDate<=CASE WHEN @ToDate IS NULL THEN vfl.CreatedDate ELSE @ToDate END
USE AdventureWorks2012;
GO
IF
(SELECT COUNT(*) FROM Production.Product WHERE Name LIKE 'Touring-3000%' ) > 5
PRINT 'There are more than 5 Touring-3000 bicycles.'
ELSE PRINT 'There are 5 or less Touring-3000 bicycles.' ;
GO
WHERE (IsNumeric(@OrderNumber) <> 1 OR OrderNumber = @OrderNumber) AND (IsNumber(@OrderNumber) = 1 OR OrderNumber LIKE '%' + @OrderNumber + '%')