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SET @@session.storage_engine = 'MyISAM';
# Case 1. All non-stored columns.
# This scenario is currently impossible due to the fact that virtual columns
# with a constant expression are not allowed.
# Case 2. CREATE
# - Column1: "real"
# - Column 2: virtual non-stored
create table t1 (a int, b int as (-a));
insert into t1 values (1,default);
select * from t1;
a b
1 -1
insert into t1 values (2,default);
select * from t1;
a b
1 -1
2 -2
drop table t1;
# Case 3. CREATE
# - Column1: "real"
# - Column 2: virtual stored
create table t1 (a int, b int as (-a) persistent);
insert into t1 values (1,default);
select * from t1;
a b
1 -1
insert into t1 values (2,default);
select * from t1;
a b
1 -1
2 -2
drop table t1;
# Case 4. CREATE
# - Column1: virtual non-stored
# - Column2: "real"
create table t1 (a int as (-b), b int);
insert into t1 values (default,1);
select * from t1;
a b
-1 1
insert into t1 values (default,2);
select * from t1;
a b
-1 1
-2 2
drop table t1;
# Case 5. CREATE
# - Column1: virtual stored
# - Column2: "real"
create table t1 (a int as (-b) persistent, b int);
insert into t1 values (default,1);
select * from t1;
a b
-1 1
insert into t1 values (default,2);
select * from t1;
a b
-1 1
-2 2
drop table t1;
# Case 6. CREATE
# - Column1: "real"
# - Column2: virtual non-stored
# - Column3: virtual stored
create table t1 (a int, b int as (-a), c int as (-a) persistent);
insert into t1 values (1,default,default);
select * from t1;
a b c
1 -1 -1
insert into t1 values (2,default,default);
select * from t1;
a b c
1 -1 -1
2 -2 -2
drop table t1;
# Case 7. ALTER. Modify virtual stored -> virtual non-stored
create table t1 (a int, b int as (a % 2) persistent);
alter table t1 modify b int as (a % 2);
ERROR HY000: 'Changing the STORED status' is not yet supported for computed columns
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`a` int(11) DEFAULT NULL,
`b` int(11) AS (a % 2) PERSISTENT
) ENGINE=MyISAM DEFAULT CHARSET=latin1
drop table t1;
# Case 8. ALTER. Modify virtual non-stored -> virtual stored
create table t1 (a int, b int as (a % 2));
alter table t1 modify b int as (a % 2) persistent;
ERROR HY000: 'Changing the STORED status' is not yet supported for computed columns
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`a` int(11) DEFAULT NULL,
`b` int(11) AS (a % 2) VIRTUAL
) ENGINE=MyISAM DEFAULT CHARSET=latin1
drop table t1;
# Case 9. CREATE LIKE
# - Column1: "real"
# - Column2: virtual non-stored
# - Column3: virtual stored
create table t1 (a int, b int as (-a), c int as (-a) persistent);
create table t2 like t1;
insert into t2 values (1,default,default);
select * from t2;
a b c
1 -1 -1
insert into t2 values (2,default,default);
select * from t2;
a b c
1 -1 -1
2 -2 -2
drop table t2;
drop table t1;
# Case 10. ALTER. Dropping a virtual non-stored column.
# - Column1: virtual non-stored
# - Column2: "real"
create table t1 (a int as (-b), b int, c varchar(5));
insert into t1 values (default,1,'v1');
insert into t1 values (default,2,'v2');
select * from t1;
a b c
-1 1 v1
-2 2 v2
alter table t1 drop column a;
select * from t1;
b c
1 v1
2 v2
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`b` int(11) DEFAULT NULL,
`c` varchar(5) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1
drop table t1;
# Case 11. ALTER. Dropping a virtual stored column.
# - Column1: virtual stored
# - Column2: "real"
create table t1 (a int as (-b) persistent, b int, c char(5));
insert into t1 values (default,1,'v1');
insert into t1 values (default,2,'v2');
select * from t1;
a b c
-1 1 v1
-2 2 v2
alter table t1 drop column a;
select * from t1;
b c
1 v1
2 v2
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`b` int(11) DEFAULT NULL,
`c` char(5) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1
drop table t1;
# Case 12. ALTER. Adding a new virtual non-stored column.
create table t1 (a int, b datetime);
insert into t1 values (1,'2008-09-04');
insert into t1 values (2,'2008-09-05');
select * from t1;
a b
1 2008-09-04 00:00:00
2 2008-09-05 00:00:00
alter table t1 add column c int as (dayofyear(b)) after a;
select * from t1;
a c b
1 248 2008-09-04 00:00:00
2 249 2008-09-05 00:00:00
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`a` int(11) DEFAULT NULL,
`c` int(11) AS (dayofyear(b)) VIRTUAL,
`b` datetime DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1
drop table t1;
# Case 13. ALTER. Adding a new virtual stored column.
create table t1 (a int, b datetime);
insert into t1 values (1,'2008-09-04');
insert into t1 values (2,'2008-09-05');
select * from t1;
a b
1 2008-09-04 00:00:00
2 2008-09-05 00:00:00
alter table t1 add column c int as (dayofyear(b)) persistent after a;
select * from t1;
a c b
1 248 2008-09-04 00:00:00
2 249 2008-09-05 00:00:00
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`a` int(11) DEFAULT NULL,
`c` int(11) AS (dayofyear(b)) PERSISTENT,
`b` datetime DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1
drop table t1;
# Case 14. ALTER. Changing the expression of a virtual stored column.
create table t1 (a int, b datetime, c int as (week(b)) persistent);
insert into t1 values (1,'2008-09-04',default);
insert into t1 values (2,'2008-09-05',default);
select * from t1;
a b c
1 2008-09-04 00:00:00 35
2 2008-09-05 00:00:00 35
alter table t1 change column c c int as (week(b,1)) persistent;
select * from t1;
a b c
1 2008-09-04 00:00:00 36
2 2008-09-05 00:00:00 36
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`a` int(11) DEFAULT NULL,
`b` datetime DEFAULT NULL,
`c` int(11) AS (week(b,1)) PERSISTENT
) ENGINE=MyISAM DEFAULT CHARSET=latin1
drop table t1;
# Case 15. ALTER. Changing the expression of a virtual non-stored column.
create table t1 (a int, b datetime, c int as (week(b)));
insert into t1 values (1,'2008-09-04',default);
insert into t1 values (2,'2008-09-05',default);
select * from t1;
a b c
1 2008-09-04 00:00:00 35
2 2008-09-05 00:00:00 35
alter table t1 change column c c int as (week(b,1));
select * from t1;
a b c
1 2008-09-04 00:00:00 36
2 2008-09-05 00:00:00 36
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`a` int(11) DEFAULT NULL,
`b` datetime DEFAULT NULL,
`c` int(11) AS (week(b,1)) VIRTUAL
) ENGINE=MyISAM DEFAULT CHARSET=latin1
drop table t1;
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