CREATE TABLE T1 (i int)
CREATE TABLE T2 (i int)
INSERT T2 VALUES(1)

set statistics io on
set nocount on

PRINT 'IF T1 T2'
IF EXISTS(select * from T1) AND EXISTS(select * from T2)
SELECT 'YES'

PRINT 'WHERE T1 T2'
IF EXISTS(
	SELECT 1
	WHERE EXISTS(select * from T1) AND EXISTS(select * from T2)
)
SELECT 'YES'

PRINT 'WHERE T2 T1'
IF EXISTS(
	SELECT 1
	WHERE EXISTS(select * from T2) AND EXISTS(select * from T1)
)
SELECT 'YES'

DROP TABLE T1 
DROP TABLE T2

IF T1 T2
Table 'T2'. Scan count 1, logical reads 1, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'T1'. Scan count 1, logical reads 0, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

WHERE T1 T2
Table 'Worktable'. Scan count 0, logical reads 0, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'T1'. Scan count 1, logical reads 0, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

WHERE T2 T1
Table 'T1'. Scan count 1, logical reads 0, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'T2'. Scan count 1, logical reads 1, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.