How to get the length of char or varchar field in sql server?

I want to write a script for SQL Server, which changes the table from ASCII to UNICODE.For that i need to change Char(n) to nchar(n), si开发者_如何学JAVAmilarly for varchar(n) to NVarchar(n).But i am not able to find out the value of n. Can anybody tell me, how can I get the value of n.

Thanks In Advance

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try this:

SELECT
    sh.name+'.'+o.name AS ObjectName
        ,o.type_desc AS ObjectType
        ,s.name as ColumnName
        ,CASE
             WHEN t.name IN ('char','varchar') THEN t.name+'('+CASE WHEN s.max_length<0 then 'MAX' ELSE CONVERT(varchar(10),s.max_length) END+')'
             WHEN t.name IN ('nvarchar','nchar') THEN t.name+'('+CASE WHEN s.max_length<0 then 'MAX' ELSE CONVERT(varchar(10),s.max_length/2) END+')'
            WHEN t.name IN ('numeric') THEN t.name+'('+CONVERT(varchar(10),s.precision)+','+CONVERT(varchar(10),s.scale)+')'
             ELSE t.name
         END AS DataType
        ,CASE
             WHEN s.is_nullable=1 THEN 'NULL'
            ELSE 'NOT NULL'
        END AS Nullable
        ,CASE
             WHEN ic.column_id IS NULL THEN ''
             ELSE ' identity('+ISNULL(CONVERT(varchar(10),ic.seed_value),'')+','+ISNULL(CONVERT(varchar(10),ic.increment_value),'')+')='+ISNULL(CONVERT(varchar(10),ic.last_value),'null')
         END
        +CASE
             WHEN sc.column_id IS NULL THEN ''
             ELSE ' computed('+ISNULL(sc.definition,'')+')'
         END
        +CASE
             WHEN cc.object_id IS NULL THEN ''
             ELSE ' check('+ISNULL(cc.definition,'')+')'
         END
            AS MiscInfo
    FROM sys.columns                           s
        INNER JOIN sys.types                   t ON s.system_type_id=t.system_type_id and t.is_user_defined=0
        INNER JOIN sys.objects                 o ON s.object_id=o.object_id
        INNER JOIN sys.schemas                sh on o.schema_id=sh.schema_id
        LEFT OUTER JOIN sys.identity_columns  ic ON s.object_id=ic.object_id AND s.column_id=ic.column_id
        LEFT OUTER JOIN sys.computed_columns  sc ON s.object_id=sc.object_id AND s.column_id=sc.column_id
        LEFT OUTER JOIN sys.check_constraints cc ON s.object_id=cc.parent_object_id AND s.column_id=cc.parent_column_id
    WHERE o.name='YourTableName'
    order by 1,s.column_id

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Never used it, but by quickly googling around:

sp_columns <table_name>

?

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Look at all the nice things in your INFORMATION_SCHEMA. Lots of views, and some even contain what you ask for ;)

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--For the value of 'n' use:

Select 
    Character_Maximum_Length AS [Size] 
FROM 
    INFORMATION_SCHEMA.Columns
WHERE 
    TABLE_NAME = 'yourTable' 
    AND COLUMN_NAME = 'yourColumn'