How to get the size of a varchar[n] field in one SQL statement?

Question

Suppose that I have a SQL table that has a varchar[1000] field called \"Remarks\".

I would like to craft a single SQL statement, which when executed, will return 100

Answer 1

For t-SQL I use the following query for varchar columns (shows the collation and is_null properties):

SELECT
    s.name
    , o.name as table_name
    , c.name as column_name
    , t.name as type
    , c.max_length
    , c.collation_name
    , c.is_nullable
FROM
    sys.columns c
    INNER JOIN sys.objects o ON (o.object_id = c.object_id)
    INNER JOIN sys.schemas s ON (s.schema_id = o.schema_id)
    INNER JOIN sys.types t ON (t.user_type_id = c.user_type_id)
WHERE
    s.name = 'dbo'
    AND t.name IN ('varchar') -- , 'char', 'nvarchar', 'nchar')
ORDER BY
    o.name, c.name

Answer 2

I was looking for the TOTAL size of the column and hit this article, my solution is based off of MarcE's.

SELECT sum(DATALENGTH(your_field)) AS FIELDSIZE FROM your_table

Answer 3

On SQL Server specifically:

SELECT DATALENGTH(Remarks) AS FIELDSIZE FROM mytable

Documentation

Answer 4

This will work on SQL SERVER...

SELECT COL_LENGTH('Table', 'Column')

Answer 5

select column_name, data_type, character_maximum_length    
  from information_schema.columns  
 where table_name = 'myTable'

Answer 6

This is a function for calculating max valid length for varchar(Nn):

CREATE FUNCTION [dbo].[GetMaxVarcharColumnLength] (@TableSchema NVARCHAR(MAX), @TableName NVARCHAR(MAX), @ColumnName VARCHAR(MAX))
RETURNS INT
AS
BEGIN
    RETURN (SELECT character_maximum_length FROM information_schema.columns  
            WHERE table_schema = @TableSchema AND table_name = @TableName AND column_name = @ColumnName);
END

Usage:

IF LEN(@Name) > [dbo].[GetMaxVarcharColumnLength]('person', 'FamilyStateName', 'Name') 
            RETURN [dbo].[err_Internal_StringForVarcharTooLong]();