Alter在SQL Server中的所有列的数据类型

Question

当我进口表在SQL它建议真正的数据类型，现在我想改变所有列双师型 ...

是否有任何脚本来自动执行此操作在SQL枭雄工作室

我的表是500列：

`After doing` EXECUTE sp_help traS 

Col Type Comp len Prec Scale Nullable TrimTrailing Fixed Collation 
------------------------------------------------------------------------------- 
x1 real no 4 24  NULL yes (n/a) (n/a) NULL 
x2 real no 4 24  NULL yes (n/a) (n/a) NULL 
x3 real no 4 24  NULL yes (n/a) (n/a) NULL 
x4 real no 4 24  NULL yes (n/a) (n/a) NULL 
... 
x500 real no 4 24  NULL yes (n/a) (n/a) NULL 

Answer 1

下面的代码将放置列的列表到一个临时表称为@cols，遍历该表，生成alter table alter column声明，并为每列执行它。

如果您需要排除列，则应该包含那些位于从information_schema.columns中选择的NOT IN谓词中的列。

declare @cols table (i int identity, colname varchar(100)) 
insert into @cols 
select column_name 
from information_schema.COLUMNS 
where TABLE_NAME = 'yourtable' 
and COLUMN_NAME not in ('exclude1', 'exclude2') 

declare @i int, @maxi int 
select @i = 1, @maxi = MAX(i) from @cols 

declare @sql nvarchar(max) 

while(@i <= @maxi) 
begin 
    select @sql = 'alter table yourtable alter column ' + colname + ' decimal(18,4) NULL' 
    from @cols 
    where i = @i 

    exec sp_executesql @sql 

    select @i = @i + 1 
end 

Answer 2

粗糙的伪代码如下所示。这是未经测试但是我没有VM方便

-- Create a cursor that will iterate through 
-- all the rows that meet the criteria DECLARE csr CURSOR FOR 
-- This query attempts to define the set of columns 
-- that are reals 
SELECT 
    SC.name AS column_name 
FROM 
    sys.tables ST 
    INNER JOIN 
     sys.columns SC 
     ON SC.object_id = ST.object_id 
    INNER JOIN 
     sys.types T 
     -- these column names are close but not right 
     ON T.type_id = SC.system_type_id 
WHERE 
    -- make this your table name 
    ST.name = 'traS' 
    -- look at actual values in sys.types 
    AND T.name = 'real' 

DECLARE 
    -- this holds the current column name 
    @column_name sysname 
, @base_query varchar(max) 
, @actual_query varchar(max) 

-- template query for fixing what's buggered 
SET @base_query = 'ALTER TABLE traS ALTER COLUMN [<X/>] decimal(18,2) NULL' 

FETCH NEXT FROM csr 
INTO @column_name 
WHILE (@@FETCH_STATUS <> -1) BEGIN 
    IF (@@FETCH_STATUS <> -2) 
    BEGIN 
     BEGIN TRY 
      SET @actual_query = REPLACE(@base_query, '<X/>', @column_name) 
      EXECUTE (@actual_query) 
     END TRY 
     BEGIN CATCH 
      PRINT 'Failed executing statement ' 
      PRINT @actual_query 
     END CATCH 
    END 
    FETCH NEXT FROM csr 
    INTO @colum_name 
END 
CLOSE csr 
DEALLOCATE csr 

橙色条架空说我太慢了，但我会提交反正我花了太多的时间打字;）