如何在WHERE子句中进行区分大小写的搜索(我使用的是SQL Server)？

Question

我想在我的SQL查询中进行区分大小写的搜索.但默认情况下,SQL Server不考虑字符串的大小写.

有关如何在SQL查询中进行区分大小写搜索的任何想法？

Answer 1

通过使用排序规则或转换为二进制,如下所示:

SELECT *
FROM Users
WHERE   
    Username = @Username COLLATE SQL_Latin1_General_CP1_CS_AS
    AND Password = @Password COLLATE SQL_Latin1_General_CP1_CS_AS
    AND Username = @Username 
    AND Password = @Password 

存在用户名/密码的重复以使引擎具有使用索引的可能性.上面的排序规则是区分大小写的排序规则,如有必要,请更改为您需要的排序规则.

第二个,转换为二进制,可以这样做:

SELECT *
FROM Users
WHERE   
    CAST(Username as varbinary(100)) = CAST(@Username as varbinary))
    AND CAST(Password as varbinary(100)) = CAST(@Password as varbinary(100))
    AND Username = @Username 
    AND Password = @Password 

Answer 2

可以通过更改排序来完成.默认情况下,它不区分大小写.

摘自链接:

SELECT 1
FROM dbo.Customers
WHERE   CustID = @CustID COLLATE SQL_Latin1_General_CP1_CS_AS
    AND CustPassword = @CustPassword COLLATE SQL_Latin1_General_CP1_CS_AS

Answer 3

您可以使用convert to varbinary进行查询 - 这很容易.例:

Select * from your_table where convert(varbinary, your_column) = convert(varbinary, 'aBcD') 

Answer 4

使用BINARY_CHECKSUM

SELECT 
FROM Users
WHERE   
    BINARY_CHECKSUM(Username) = BINARY_CHECKSUM(@Username)
    AND BINARY_CHECKSUM(Password) = BINARY_CHECKSUM(@Password)

Answer 5

在 MySQL 中，如果您不想更改排序规则并希望执行区分大小写的搜索，则只需使用二进制关键字，如下所示：

SELECT * FROM table_name WHERE binary username=@search_parameter and binary password=@search_parameter

Answer 6

使用HASHBYTES

declare @first_value nvarchar(1) = 'a'
declare @second_value navarchar(1) = 'A'

if HASHBYTES('SHA1',@first_value) = HASHBYTES('SHA1',@second_value) begin
    print 'equal'
end else begin
    print 'not equal'
end

-- output:
-- not equal

......在where子句中

declare @example table (ValueA nvarchar(1), ValueB nvarchar(1))

insert into @example (ValueA, ValueB)
values  ('a', 'A'),
        ('a', 'a'),
        ('a', 'b')

select  ValueA + ' = ' + ValueB
from    @example
where   hashbytes('SHA1', ValueA) = hashbytes('SHA1', ValueB)

-- output:
-- a = a

select  ValueA + ' <> ' + ValueB
from    @example
where   hashbytes('SHA1', ValueA) <> hashbytes('SHA1', ValueB)

-- output:
-- a <> A
-- a <> b

或找到一个价值

declare @value_b nvarchar(1) = 'A'

select  ValueB + ' = ' + @value_b
from    @example
where   hashbytes('SHA1', ValueB) = hasbytes('SHA1', @value_b)

-- output:
-- A = A

Answer 7

使用Latin1_General_CS作为SQL数据库中的排序规则