Can I somehow select a column if exists in a view, but ignore the column if it does not exist?
SELECT
CASE
WHEN EXISTS(SELECT 1 FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'MyView' AND COLUMN_NAME = 'MyColumn')
THEN MyView.MyColumn
ELSE NULL
END AS [Sometimes]
FROM
MyView
Rig开发者_JAVA技巧ht now, that returns a "Msg 207 Invalid column name" error.
Perhaps some option to ignore that error is possible?
You can do it by using dynamic SQL:
declare @sql varchar(200)
IF EXISTS(SELECT 1 FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'MyView' AND COLUMN_NAME = 'MyColumn')
BEGIN
select @sql = "SELECT Column1m Column2, MyColum from MyView"
END
ELSE
BEGIN
select @sql = "SELECT Column1m Column2, null as MyColum from MyView"
END
-- executes dynamic sql
EXEC @sql
No, this isn't possible. The column-access has to be compiled, if nothing else, and this happens before the expression that suppresses it is evaluated. You need to generate SQL on-the-fly for this.
The best you can do is
if EXISTS(SELECT 1 FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'MyView' AND COLUMN_NAME = 'MyColumn')
Select MyView.MyColumn from MyView
else
Select NULL MyColumn
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