问题很简单:源查询中的一个或多个列包含的数据超过了目标列的长度。一个简单的解决方案是使用源查询并在每一列上执行Max(Len(source col))。也就是说,

Select Max(Len(TextCol1))
    , Max(Len(TextCol2))
    , Max(Len(TextCol3))
    , ...
From ...

然后将这些长度与目标表中的数据类型长度进行比较。至少有一个超出了其目标列的长度。

如果你绝对肯定情况不应该是这样，也不关心是不是这样，那么另一个解决方案是强制强制转换源查询列到它们的目标长度(这将截断任何太长的数据):

Select Cast(TextCol1 As varchar(...))
    , Cast(TextCol2 As varchar(...))
    , Cast(TextCol3 As varchar(...))
    , ...
From ...

我写了一个有用的存储过程来帮助识别和解决使用INSERT SELECT语句时的文本截断问题(字符串或二进制数据将被截断)。它只比较字段CHAR, VARCHAR, NCHAR和NVARCHAR，并在可能导致错误的情况下逐字段返回一个评估字段。

EXEC dbo.GetFieldStringTruncate SourceTableName, TargetTableName

这个存储过程针对的是在执行INSERT SELECT语句时的文本截断问题。 此存储过程的操作取决于用户之前是否识别出有问题的INSERT语句。然后将源数据插入到全局临时表中。建议使用SELECT INTO语句。 必须在SELECT语句的每个字段的别名中使用目标表字段的相同名称。

函数代码:

DECLARE @strSQL nvarchar(1000)
IF NOT EXISTS (SELECT * FROM dbo.sysobjects where id = OBJECT_ID(N'[dbo].[GetFieldStringTruncate]'))
    BEGIN
        SET @strSQL = 'CREATE PROCEDURE [dbo].[GetFieldStringTruncate] AS RETURN'
        EXEC sys.sp_executesql @strSQL
    END

GO

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

/*
------------------------------------------------------------------------------------------------------------------------
    Description:    
                    Syntax 
                    ---------------
                    dbo.GetFieldStringTruncate(SourceTable, TargetTable)
                    +---------------------------+-----------------------+
                    |   SourceTableName         |   VARCHAR(255)        |
                    +---------------------------+-----------------------+
                    |   TargetTableName         |   VARCHAR(255)        |
                    +---------------------------+-----------------------+

                    Arguments
                    ---------------
                    SourceTableName
                    The name of the source table. It should be a temporary table using double charp '##'. E.g. '##temp'

                    TargetTableName
                    The name of the target table. It is the table that receives the data used in the INSERT INTO stament.

                    Return Type
                    ----------------
                    Returns a table with a list of all the fields with the type defined as text and performs an evaluation indicating which field would present the problem of string truncation.

                    Remarks
                    ----------------
                    This stored procedure is oriented to the problem of text truncation when an INSERT SELECT statement is made.
                    The operation of this stored procedure depends on the user previously identifying the INSERT statement with the problem. Then inserting the source data into a global temporary table. The SELECT INTO statement is recommended.
                    You must use the same name of the field of the destination table in the alias of each field of the SELECT statement.

                    Examples
                    ====================================================================================================

                    --A. Test basic

                        IF EXISTS (SELECT * FROM sys.objects  WHERE OBJECT_ID = OBJECT_ID(N'[dbo].[tblDestino]') AND TYPE IN (N'U'))
                            DROP TABLE tblDestino

                        CREATE TABLE tblDestino
                        (
                            Id INT IDENTITY,
                            Field1 VARCHAR(10),
                            Field2 VARCHAR(12),
                            Field3 VARCHAR(11),
                            Field4 VARCHAR(16),
                            Field5 VARCHAR(5),
                            Field6 VARCHAR(1),
                            Field7 VARCHAR(1),
                            Field8 VARCHAR(6),
                            Field9 VARCHAR(6),
                            Field10 VARCHAR(50),
                            Field11 VARCHAR(50),
                            Field12 VARCHAR(50)
                        )

                        INSERT INTO dbo.tblDestino
                        (
                             Field1 ,
                             Field2 ,
                             Field3 ,
                             Field4 ,
                             Field5 ,
                             Field6 ,
                             Field7 ,
                             Field8 ,
                             Field9 ,
                             Field10 ,
                             Field11 ,
                             Field12
                            )
                        SELECT 
                             '123456789' , -- Field1 - varchar(10)
                             '123456789' , -- Field2 - varchar(12)
                             '123456789' , -- Field3 - varchar(11)
                             '123456789' , -- Field4 - varchar(16)
                             '123456789' , -- Field5 - varchar(5)
                             '123456789' , -- Field6 - varchar(1)
                             '123456789' , -- Field7 - varchar(1)
                             '123456789' , -- Field8 - varchar(6)
                             '123456789' , -- Field9 - varchar(6)
                             '123456789' , -- Field10 - varchar(50)
                             '123456789' , -- Field11 - varchar(50)
                             '123456789'  -- Field12 - varchar(50)
                        GO  

                    Result:
                        String or binary data would be truncated


                    *Here you get the truncation error. Then, we proceed to save the information in a global temporary table. 
                    *IMPORTANT REMINDER: You must use the same name of the field of the destination table in the alias of each field of the SELECT statement.


                    Process:

                        IF OBJECT_ID('tempdb..##TEMP') IS NOT NULL DROP TABLE ##TEMP
                        go
                        SELECT 
                             [Field1] = '123456789' ,
                             [Field2] = '123456789' ,
                             [Field3] = '123456789' ,
                             [Field4] = '123456789' ,
                             [Field5] = '123456789' ,
                             [Field6] = '123456789' ,
                             [Field7] = '123456789' ,
                             [Field8] = '123456789' ,
                             [Field9] = '123456789' ,
                             [Field10] = '123456789' ,
                             [Field11] = '123456789' ,
                             [Field12] = '123456789'  
                        INTO ##TEMP

                    Result:
                    (1 row(s) affected)

                    Test:
                        EXEC dbo.GetFieldStringTruncate @SourceTableName = '##TEMP', @TargetTableName = 'tblDestino'

                    Result:

                        (12 row(s) affected)
                        ORIGEN Nombre Campo        ORIGEN Maximo Largo  DESTINO Nombre Campo     DESTINO Tipo de campo   Evaluación
                        -------------------------- -------------------- ------------------------ ----------------------- -------------------------
                        Field1                     9                    02 - Field1              VARCHAR(10)             
                        Field2                     9                    03 - Field2              VARCHAR(12)             
                        Field3                     9                    04 - Field3              VARCHAR(11)             
                        Field4                     9                    05 - Field4              VARCHAR(16)             
                        Field5                     9                    06 - Field5              VARCHAR(5)              possible field with error
                        Field6                     9                    07 - Field6              VARCHAR(1)              possible field with error
                        Field7                     9                    08 - Field7              VARCHAR(1)              possible field with error
                        Field8                     9                    09 - Field8              VARCHAR(6)              possible field with error
                        Field9                     9                    10 - Field9              VARCHAR(6)              possible field with error
                        Field10                    9                    11 - Field10             VARCHAR(50)             
                        Field11                    9                    12 - Field11             VARCHAR(50)             
                        Field12                    9                    13 - Field12             VARCHAR(50)             

                    ====================================================================================================

    ------------------------------------------------------------------------------------------------------------

    Responsible:    Javier Pardo 
    Date:           October 19/2018
    WB tests:       Javier Pardo 

    ------------------------------------------------------------------------------------------------------------

*/

ALTER PROCEDURE dbo.GetFieldStringTruncate
(
    @SourceTableName AS VARCHAR(255)
    , @TargetTableName AS VARCHAR(255)
)
AS
BEGIN
    BEGIN TRY

        DECLARE @colsUnpivot AS NVARCHAR(MAX),
            @colsUnpivotConverted AS NVARCHAR(MAX),
           @query  AS NVARCHAR(MAX)

        SELECT @colsUnpivot = stuff((
                    SELECT DISTINCT ',' + QUOTENAME(col.NAME)
                    FROM tempdb.sys.tables tab
                    INNER JOIN tempdb.sys.columns col
                        ON col.object_id = tab.object_id
                    INNER JOIN tempdb.sys.types typ
                        ON col.system_type_id = TYP.system_type_id
                    WHERE tab.NAME = @SourceTableName
                    FOR XML path('')
                    ), 1, 1, '')
                ,@colsUnpivotConverted = stuff((
                    SELECT DISTINCT ',' + 'CONVERT(VARCHAR(MAX),' + QUOTENAME(col.NAME) + ') AS ' + QUOTENAME(col.NAME)
                    FROM tempdb.sys.tables tab
                    INNER JOIN tempdb.sys.columns col
                        ON col.object_id = tab.object_id
                    INNER JOIN tempdb.sys.types typ
                        ON col.system_type_id = TYP.system_type_id
                    WHERE tab.NAME = @SourceTableName
                    FOR XML path('')
                    ), 1, 1, '')


        --https://stackoverflow.com/questions/11158017/column-conflicts-with-the-type-of-other-columns-in-the-unpivot-list
        IF OBJECT_ID('tempdb..##TablaConMaximos') IS NOT NULL DROP TABLE ##TablaConMaximos

        set @query 
          = 'SELECT u.d AS colname, MAX(LEN(u.data)) as [maximo_largo]
            INTO ##TablaConMaximos
            FROM 
            (
                SELECT ' + @colsUnpivotConverted + '
                FROM ' + @SourceTableName + '
            ) T
            UNPIVOT
             (
                data
                for d in ('+ @colsunpivot +')
             ) u
             GROUP BY u.d'

        PRINT @query

        exec sp_executesql @query;

        ------------------------------------------------------------------------------------------------------------
        SELECT --'Nombre de campo' = RIGHT('00' + ISNULL(CONVERT(VARCHAR,col.column_id),''),2) + ' - ' + col.name + ' '
            --, 'Tipo de campo' = ISNULL(CONVERT(VARCHAR,upper(typ.name)),'') + '(' + ISNULL(CONVERT(VARCHAR,col.max_length),'') + ')'
            [ORIGEN Nombre Campo] = tcm.colname
            , [ORIGEN Maximo Largo] = tcm.maximo_largo
            , [DESTINO Nombre Campo] = DESTINO.[Nombre de campo]
            , [DESTINO Tipo de campo] = DESTINO.[Tipo de campo]
            , [Evaluación] = CASE WHEN DESTINO.maximo_largo < tcm.maximo_largo THEN 'possible field with error' ELSE '' END
            --, * 
        FROM tempdb.sys.tables tab
            INNER JOIN tempdb.sys.columns col
                ON col.object_id = tab.object_id
            INNER JOIN tempdb.sys.types typ
                ON col.system_type_id = TYP.system_type_id
            RIGHT JOIN 
                (
                    SELECT column_id
                        , [Nombre de campo] = RIGHT('00' + ISNULL(CONVERT(VARCHAR,col.column_id),''),2) + ' - ' + col.name + ' '
                        , [Tipo de campo] = ISNULL(CONVERT(VARCHAR,upper(typ.name)),'') + '(' + ISNULL(CONVERT(VARCHAR,col.max_length),'') + ')'
                        , [maximo_largo] = col.max_length
                        , [colname] = col.name
                    FROM sys.tables tab
                        INNER JOIN sys.columns col
                            ON col.object_id = tab.object_id
                        INNER JOIN sys.types typ
                            ON col.system_type_id = TYP.system_type_id
                    WHERE tab.NAME = @TargetTableName
                ) AS DESTINO
                    ON col.name = DESTINO.colname
            INNER JOIN ##TablaConMaximos tcm
                ON tcm.colname = DESTINO.colname

        WHERE tab.NAME = @SourceTableName
            AND typ.name LIKE '%char%'
        ORDER BY col.column_id

    END TRY
    BEGIN CATCH
        SELECT 'Internal error ocurred' AS Message
    END CATCH   

END

目前只支持数据类型CHAR, VARCHAR, NCHAR和NVARCHAR。你可以在下面的链接中找到这段代码的最后一个versión，我们会互相帮助来改进它。GetFieldStringTruncate.sql

https://gist.github.com/jotapardo/210e85338f87507742701aa9d41cc51d

我也遇到过类似的问题。我将数据从一个表复制到一个完全相同的表，除了名称。

最后，我使用SELECT into语句将源表转储到临时表中。

SELECT *
INTO TEMP_TABLE
FROM SOURCE_TABLE;

我比较了源表和临时表的模式。我发现其中一列是varchar(4000)，而我期待的是varchar(250)。

更新: 如果你感兴趣，varchar(4000)问题可以在这里解释:

对于Nvarchar(Max)，我只能在TSQL中获得4000个字符?

希望这能有所帮助。

是的，我也面临着这样的问题。

REMARKS VARCHAR(500)
to
REMARKS VARCHAR(1000)

在这里，我将备注文件的长度从500更改为1000

这可能是一个具有挑战性的错误。以下是AmirCharania在https://connect.microsoft.com/SQLServer/feedback/details/339410/网站上发表的评论。

我调整了AmirCharania给出的答案，用于选择实际表中的数据，而不是临时表。首先选择你的数据集到一个开发表中，然后运行以下命令:

WITH CTE_Dev
AS (
    SELECT C.column_id
        ,ColumnName = C.NAME
        ,C.max_length
        ,C.user_type_id
        ,C.precision
        ,C.scale
        ,DataTypeName = T.NAME
    FROM sys.columns C
    INNER JOIN sys.types T ON T.user_type_id = C.user_type_id
    WHERE OBJECT_ID = OBJECT_ID('YOUR TARGET TABLE NAME HERE, WITH SCHEMA')
    )
    ,CTE_Temp
AS (
    SELECT C.column_id
        ,ColumnName = C.NAME
        ,C.max_length
        ,C.user_type_id
        ,C.precision
        ,C.scale
        ,DataTypeName = T.NAME
    FROM sys.columns C
    INNER JOIN sys.types T ON T.user_type_id = C.user_type_id
    WHERE OBJECT_ID = OBJECT_ID('YOUR TEMP TABLE NAME HERE, WITH SCHEMA')
    )
SELECT *
FROM CTE_Dev D
FULL OUTER JOIN CTE_Temp T ON D.ColumnName = T.ColumnName
WHERE ISNULL(D.max_length, 0) < ISNULL(T.max_length, 999)

如果你使用的是SQL Server 2016-2017: 要修复此问题，请打开跟踪标志460

DBCC TRACEON(460, 1);
GO

确保你在以下情况下将其关闭:

DBCC TRACEOFF(460, 1);
GO

源