如何獲取sql server中char或varchar字段的長度？

Question

我想爲SQL Server編寫一個腳本，該腳本將表格從ASCII更改爲UNICODE。爲此，我需要將Char（n）更改爲nchar（n），對於NVcharchar（n）varchar（n）也是如此。我無法找出n的價值。 有人可以告訴我，我怎麼能得到n的價值。

在此先感謝

Answer 1

從來沒有使用過，但通過快速周圍的Googling：

sp_columns <table_name> 

？

Answer 2

查看INFORMATION_SCHEMA中的所有好東西。意見很多，有的甚至包含你所求的;）

Answer 3

試試這個：

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 

Answer 4

--For the value of 'n' use: 

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