选择LIKE或CHARINDEX（）函数以使用SQL查找一些特殊的unicode字符

我的第二个和第三个查询没有输出任何记录，而第一个查询输出一条记录，这有什么问题

查询1:

DECLARE @FullName nvarchar(50)
DECLARE @FULLNamelike nvarchar(50)
SET @FullName = 'NGUYỄN THỊ DIỆU'
SET @FULLNamelike = N'%' + @FullName + '%'

SELECT HR_CInformation.[CandidateId]
    ,HR_CInformation.[FullName]
    ,HR_CInformation.[Email]
FROM [dbo].[IT_HR_Candidate_Information] HR_CInformation
WHERE (HR_CInformation.[FullName] like N'%NGUYỄN THỊ DIỆU%' OR @FULLNamelike = '')

DECLARE @FullName nvarchar(50)
DECLARE @FULLNamelike nvarchar(50)
SET @FullName = 'NGUYỄN THỊ DIỆU'
SET @FULLNamelike = N'%' + @FullName + '%'

SELECT HR_CInformation.[CandidateId]
    ,HR_CInformation.[FullName]
    ,HR_CInformation.[Email]
FROM [dbo].[IT_HR_Candidate_Information] HR_CInformation
WHERE (HR_CInformation.[FullName] like @FULLNamelike OR @FULLNamelike = '')

DECLARE @FullName nvarchar(50)
DECLARE @FULLNamelike nvarchar(50)
SET @FullName = 'NGUYỄN THỊ DIỆU'
SET @FULLNamelike = N'%' + @FullName + '%'

SELECT HR_CInformation.[CandidateId]
    ,HR_CInformation.[FullName]
    ,HR_CInformation.[Email]
FROM [dbo].[IT_HR_Candidate_Information] HR_CInformation
WHERE (CHARINDEX(@FULLNamelike, HR_CInformation.[FullName]) > 0 OR @FULLNamelike = '')

• 结果：21非圭亚那Ễ第N条Ị DIỆUaddieunt@gmail.com

查询2:

DECLARE @FullName nvarchar(50)
DECLARE @FULLNamelike nvarchar(50)
SET @FullName = 'NGUYỄN THỊ DIỆU'
SET @FULLNamelike = N'%' + @FullName + '%'

SELECT HR_CInformation.[CandidateId]
    ,HR_CInformation.[FullName]
    ,HR_CInformation.[Email]
FROM [dbo].[IT_HR_Candidate_Information] HR_CInformation
WHERE (HR_CInformation.[FullName] like N'%NGUYỄN THỊ DIỆU%' OR @FULLNamelike = '')

DECLARE @FullName nvarchar(50)
DECLARE @FULLNamelike nvarchar(50)
SET @FullName = 'NGUYỄN THỊ DIỆU'
SET @FULLNamelike = N'%' + @FullName + '%'

SELECT HR_CInformation.[CandidateId]
    ,HR_CInformation.[FullName]
    ,HR_CInformation.[Email]
FROM [dbo].[IT_HR_Candidate_Information] HR_CInformation
WHERE (HR_CInformation.[FullName] like @FULLNamelike OR @FULLNamelike = '')

DECLARE @FullName nvarchar(50)
DECLARE @FULLNamelike nvarchar(50)
SET @FullName = 'NGUYỄN THỊ DIỆU'
SET @FULLNamelike = N'%' + @FullName + '%'

SELECT HR_CInformation.[CandidateId]
    ,HR_CInformation.[FullName]
    ,HR_CInformation.[Email]
FROM [dbo].[IT_HR_Candidate_Information] HR_CInformation
WHERE (CHARINDEX(@FULLNamelike, HR_CInformation.[FullName]) > 0 OR @FULLNamelike = '')

查询3:

DECLARE @FullName nvarchar(50)
DECLARE @FULLNamelike nvarchar(50)
SET @FullName = 'NGUYỄN THỊ DIỆU'
SET @FULLNamelike = N'%' + @FullName + '%'

SELECT HR_CInformation.[CandidateId]
    ,HR_CInformation.[FullName]
    ,HR_CInformation.[Email]
FROM [dbo].[IT_HR_Candidate_Information] HR_CInformation
WHERE (HR_CInformation.[FullName] like N'%NGUYỄN THỊ DIỆU%' OR @FULLNamelike = '')

DECLARE @FullName nvarchar(50)
DECLARE @FULLNamelike nvarchar(50)
SET @FullName = 'NGUYỄN THỊ DIỆU'
SET @FULLNamelike = N'%' + @FullName + '%'

SELECT HR_CInformation.[CandidateId]
    ,HR_CInformation.[FullName]
    ,HR_CInformation.[Email]
FROM [dbo].[IT_HR_Candidate_Information] HR_CInformation
WHERE (HR_CInformation.[FullName] like @FULLNamelike OR @FULLNamelike = '')

DECLARE @FullName nvarchar(50)
DECLARE @FULLNamelike nvarchar(50)
SET @FullName = 'NGUYỄN THỊ DIỆU'
SET @FULLNamelike = N'%' + @FullName + '%'

SELECT HR_CInformation.[CandidateId]
    ,HR_CInformation.[FullName]
    ,HR_CInformation.[Email]
FROM [dbo].[IT_HR_Candidate_Information] HR_CInformation
WHERE (CHARINDEX(@FULLNamelike, HR_CInformation.[FullName]) > 0 OR @FULLNamelike = '')

---

这是因为您的unicode字符被转换为问号

因此，在声明变量

FullName

并为其分配unicode值时，确实需要使用

N

尝试此查询以澄清：

DECLARE @FullName nvarchar(50)
DECLARE @FullNameO nvarchar(50)
DECLARE @FullNamelike nvarchar(50)
DECLARE @FullNameOkay nvarchar(50)
SET @FullName = 'NGUYỄN THỊ DIỆU'
SET @FullNameO = N'NGUYỄN THỊ DIỆU'
SET @FullNamelike = N'%' + @FullName +'%'
SET @FullNameOkay = N'%' + @FullNameO +'%'
SELECT @FullNamelike, N'%NGUYỄN THỊ DIỆU%', @FullNameOkay

SQLFiddle：