string or binary data would be truncated. in sql server - sql

Question

How to overcome this?
I have insert statements for large tables. there were lot of columns in those tables.
Is there any simple way to find the column which is causing above error?

Answer 1

The simplest way is to increase the length of the column which is giving you the error "string or binary data would be truncated. in sql server".
Now to find which column is giving that error you can check How to find what column caused the String or binary data would be truncated message
First thing we need to know is what the columns are in the table that are (n)chars or (n)varchar
select column_name
from information_schema.columns
where table_name = 'temp'
and data_type in('varchar','char','nvarchar','nchar')
Output:
column_name
————–
Col1
Col2
Col3
Col4
Col5
That was easy, now we want to know the max length of the data in each column
declare #sql varchar(8000)
select #sql = 'select 0 as _col0 ,'
select #sql += 'max(len( ' + column_name+ ')) AS ' + column_name + ','
from information_schema.columns
where table_name = 'temp'
and data_type in('varchar','char','nvarchar','nchar')
select #sql = left(#sql,len(#sql) -1)
select #sql +=' into MaxLengths from temp'
--select #sql -debugging so simple, a caveman can do it
exec (#sql)
That code basically creates and runs the following
select 0 as _col0 ,
max(len( Col1)) AS Col1,
max(len( Col2)) AS Col2,
max(len( Col3)) AS Col3,
max(len( Col4)) AS Col4,
max(len( Col5)) AS Col5
into MaxLengths
from temp
If we now look in the MaxLengths table we will see the following
select * from MaxLengths
_col0 Col1 Col2 Col3 Col4 Col5
---------------------------------------------------
0 13 20 6 4 15
Next to figure out is what the max length of the column itself is in the table that we want to insert into
Run the following query
select character_maximum_length,column_name
from information_schema.columns
where table_name = 'TestTrunc'
and data_type in('varchar','char','nvarchar','nchar')
Result
character_maximum_length column_name
--------------------------------------------
10 Col1
15 Col2
20 Col3
3 Col4
10 Col5
We will again do this dynamically and insert the values into another table
declare #sql varchar(8000)
select #sql = 'select 0 as _col0, '
select #sql += '' + convert(varchar(20),character_maximum_length)+ ' AS ' + column_name + ','
from information_schema.columns
where table_name = 'TestTrunc'
and data_type in('varchar','char','nvarchar','nchar')
select #sql = left(#sql,len(#sql) -1)
select #sql +=' into TempTrunc '
--select #sql -debugging so simple, a caveman can do it
exec (#sql)
Now we can see what we have in the two tables
select 'TempTrunc' as TableNAme,* from TempTrunc
union all
select 'MaxLengths' as TableNAme,* from MaxLengths
TableNAme _col0 Col1 Col2 Col3 Col4 Col5
-------------------------------------------------------------
TempTrunc 0 10 15 20 3 10
MaxLengths 0 13 20 6 4 15
As you can see, all columns except for Col3 will cause the truncation problem
Of course we want to do something like this, it will tell us which columns have truncation problems
select case when t.col1 > tt.col1 then 'truncation' else 'no truncation' end as Col1,
case when t.col2 > tt.col2 then 'truncation' else 'no truncation' end as Col2,
case when t.col3 > tt.col3 then 'truncation' else 'no truncation' end as Col3,
case when t.col4 > tt.col4 then 'truncation' else 'no truncation' end as Col4,
case when t.col5 > tt.col5 then 'truncation' else 'no truncation' end as Col5
from MaxLengths t
join TempTrunc tt on t._col0 = tt._col0
Col1 Col2 Col3 Col4 Col5
------------------------------------------------------------------------------------
truncation truncation no truncation truncation truncation
Source

Answer 2

I believe you already know that this is related with inserting a string value into a column with less size
You can query table columns from know table names and compare them.
select
OBJECT_NAME(object_id),
name,
max_length,
precision,
scale
from sys.columns where object_id in (
select object_id from sys.tables where name in ('tbl','Emp')
)