USE tpch1;
select CASE WHEN NULL IS NOT NULL THEN r_regionkey='10' ELSE ''='' END from region;
CASE WHEN NULL IS NOT NULL THEN r_regionkey='10' ELSE ''='' END
1
1
1
1
1
select case r_regionkey=1 when 0 then "=1" else "<>1" end from region;
case r_regionkey=1 when 0 then "=1" else "<>1" end
=1
<>1
=1
=1
=1
select * from region where case when null is null then r_regionkey else r_regionkey > 2 end = 0;
r_regionkey	r_name	r_comment
0	AFRICA	lar deposits. blithely final packages cajole. regular waters are final requests. regular accounts are according to 
select * from region where case r_regionkey when r_regionkey = 1 then 'b' when r_regionkey=2 then "a" end > 'a';
r_regionkey	r_name	r_comment
0	AFRICA	lar deposits. blithely final packages cajole. regular waters are final requests. regular accounts are according to 
1	AMERICA	hs use ironic, even requests. s
select * from region where case r_regionkey = 1 when 1 then 'a' when r_regionkey=0 then "b" else 'else' end > 'a';
r_regionkey	r_name	r_comment
0	AFRICA	lar deposits. blithely final packages cajole. regular waters are final requests. regular accounts are according to 
2	ASIA	ges. thinly even pinto beans ca
3	EUROPE	ly final courts cajole furiously final excuse
4	MIDDLE EAST	uickly special accounts cajole carefully blithely close requests. carefully final asymptotes haggle furiousl
select case r_regionkey when r_regionkey = 1 then '=1' when r_regionkey=2 then "=2" > 'a' end alias from region;
alias
=1
=1
NULL
NULL
NULL