如果Exist语句在不应运行的情况下正在运行— MS SQL Server 2014错误

Question

In the below statement Field1 does not exist. IF EXIST will return false and the select statement on line 3 should not run.

IF EXISTS (SELECT * 
           FROM  Database1.sys.columns 
           WHERE NAME = 'Field1' 
             AND OBJECT_ID = OBJECT_ID('Database1.dbo.Table1')) 
    SELECT D.Field1 
    FROM Database1.dbo.Table1 D

However, when I run this, I get this error:

Msg 207, Level 16, State 1, Line 3
Invalid column name 'Field1'.

Is this a bug or am I doing something wrong? I need to query the table if Field1 exists.

Please note that database1 exists and field1 does not exist.

Answer 1

You'll need to use dynamic SQL:

IF EXISTS (SELECT * FROM  Database1.sys.columns WHERE NAME = 'Field1' 
AND OBJECT_ID = OBJECT_ID('Database1.dbo.Table1')) 
    EXEC('SELECT D.Field1 FROM Database1.dbo.Table1 D');

Answer 2

You had a typo I believe.

you had:

IF EXISTS (SELECT * FROM  Database1.sys.columns WHERE NAME = 'Field1' 
AND OBJECT_ID = OBJECT_ID('Database1.dbo.Table1')) 
    SELECT D.Field1 
    FROM Database1.dbo.Field1 D

try this:

IF EXISTS (SELECT * FROM  sys.columns WHERE NAME = 'Field1' 
AND OBJECT_ID = OBJECT_ID('Database1.dbo.Table1')) 
    SELECT D.Field1 
    FROM Database1.dbo.Table1 D

as I dont have the database and teh table this is my results:

Answer 3

SELECT D.Field1 
FROM Database1.dbo.Field1 D
WHERE EXISTS (SELECT 1 FROM  sys.columns WHERE NAME = 'Field1' 
              AND OBJECT_ID = OBJECT_ID('Database1.dbo.Table1'))

Using INFORMATION_SCHEMA: ( MS Docs )

SELECT D.<Field Name> 
FROM <Catalog>.<Schema>.<Table name> D
WHERE EXISTS (SELECT 1 FROM  INFORMATION_SCHEMA.COLUMNS 
              WHERE TABLE_CATALOG = <Catalog>
                    AND TABLE_SCHEMA = <Schema>
                    AND TABLE_NAME = <Table name>
                    AND COLUMN_NAME = <Column name>)

Check it here: http://rextester.com/LVB42621