mirror of
https://github.com/MariaDB/server.git
synced 2025-07-26 07:02:12 +03:00
207 lines
3.8 KiB
Plaintext
207 lines
3.8 KiB
Plaintext
SET sql_mode=ORACLE;
|
|
EXPLAIN EXTENDED SELECT 'a'||'b'||'c';
|
|
id select_type table type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL No tables used
|
|
Warnings:
|
|
Note 1003 select 'a' || 'b' || 'c' AS "'a'||'b'||'c'"
|
|
EXPLAIN EXTENDED SELECT CONCAT('a'||'b'||'c');
|
|
id select_type table type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL No tables used
|
|
Warnings:
|
|
Note 1003 select 'a' || 'b' || 'c' AS "CONCAT('a'||'b'||'c')"
|
|
SELECT '' || '';
|
|
'' || ''
|
|
|
|
SELECT '' || 'b';
|
|
'' || 'b'
|
|
b
|
|
SELECT '' || NULL;
|
|
'' || NULL
|
|
|
|
SELECT 'a' || '';
|
|
'a' || ''
|
|
a
|
|
SELECT 'a' || 'b';
|
|
'a' || 'b'
|
|
ab
|
|
SELECT 'a' || NULL;
|
|
'a' || NULL
|
|
a
|
|
SELECT NULL || '';
|
|
NULL || ''
|
|
|
|
SELECT NULL || 'b';
|
|
NULL || 'b'
|
|
b
|
|
SELECT NULL || NULL;
|
|
NULL || NULL
|
|
NULL
|
|
SELECT '' || '' || '';
|
|
'' || '' || ''
|
|
|
|
SELECT '' || '' || 'c';
|
|
'' || '' || 'c'
|
|
c
|
|
SELECT '' || '' || NULL;
|
|
'' || '' || NULL
|
|
|
|
SELECT '' || 'b' || '';
|
|
'' || 'b' || ''
|
|
b
|
|
SELECT '' || 'b' || 'c';
|
|
'' || 'b' || 'c'
|
|
bc
|
|
SELECT '' || 'b' || NULL;
|
|
'' || 'b' || NULL
|
|
b
|
|
SELECT '' || NULL || '';
|
|
'' || NULL || ''
|
|
|
|
SELECT '' || NULL || 'c';
|
|
'' || NULL || 'c'
|
|
c
|
|
SELECT '' || NULL || NULL;
|
|
'' || NULL || NULL
|
|
|
|
SELECT 'a' || '' || '';
|
|
'a' || '' || ''
|
|
a
|
|
SELECT 'a' || '' || 'c';
|
|
'a' || '' || 'c'
|
|
ac
|
|
SELECT 'a' || '' || NULL;
|
|
'a' || '' || NULL
|
|
a
|
|
SELECT 'a' || 'b' || '';
|
|
'a' || 'b' || ''
|
|
ab
|
|
SELECT 'a' || 'b' || 'c';
|
|
'a' || 'b' || 'c'
|
|
abc
|
|
SELECT 'a' || 'b' || NULL;
|
|
'a' || 'b' || NULL
|
|
ab
|
|
SELECT 'a' || NULL || '';
|
|
'a' || NULL || ''
|
|
a
|
|
SELECT 'a' || NULL || 'c';
|
|
'a' || NULL || 'c'
|
|
ac
|
|
SELECT 'a' || NULL || NULL;
|
|
'a' || NULL || NULL
|
|
a
|
|
SELECT NULL || '' || '';
|
|
NULL || '' || ''
|
|
|
|
SELECT NULL || '' || 'c';
|
|
NULL || '' || 'c'
|
|
c
|
|
SELECT NULL || '' || NULL;
|
|
NULL || '' || NULL
|
|
|
|
SELECT NULL || 'b' || '';
|
|
NULL || 'b' || ''
|
|
b
|
|
SELECT NULL || 'b' || 'c';
|
|
NULL || 'b' || 'c'
|
|
bc
|
|
SELECT NULL || 'b' || NULL;
|
|
NULL || 'b' || NULL
|
|
b
|
|
SELECT NULL || NULL || '';
|
|
NULL || NULL || ''
|
|
|
|
SELECT NULL || NULL || 'c';
|
|
NULL || NULL || 'c'
|
|
c
|
|
SELECT NULL || NULL || NULL;
|
|
NULL || NULL || NULL
|
|
NULL
|
|
CREATE TABLE t1 (a VARCHAR(10), b VARCHAR(10), c VARCHAR(10));
|
|
INSERT INTO t1 VALUES ('', '', '');
|
|
INSERT INTO t1 VALUES ('', '', 'c');
|
|
INSERT INTO t1 VALUES ('', '', NULL);
|
|
INSERT INTO t1 VALUES ('', 'b', '');
|
|
INSERT INTO t1 VALUES ('', 'b', 'c');
|
|
INSERT INTO t1 VALUES ('', 'b', NULL);
|
|
INSERT INTO t1 VALUES ('', NULL, '');
|
|
INSERT INTO t1 VALUES ('', NULL, 'c');
|
|
INSERT INTO t1 VALUES ('', NULL, NULL);
|
|
INSERT INTO t1 VALUES ('a', '', '');
|
|
INSERT INTO t1 VALUES ('a', '', 'c');
|
|
INSERT INTO t1 VALUES ('a', '', NULL);
|
|
INSERT INTO t1 VALUES ('a', 'b', '');
|
|
INSERT INTO t1 VALUES ('a', 'b', 'c');
|
|
INSERT INTO t1 VALUES ('a', 'b', NULL);
|
|
INSERT INTO t1 VALUES ('a', NULL, '');
|
|
INSERT INTO t1 VALUES ('a', NULL, 'c');
|
|
INSERT INTO t1 VALUES ('a', NULL, NULL);
|
|
INSERT INTO t1 VALUES (NULL, '', '');
|
|
INSERT INTO t1 VALUES (NULL, '', 'c');
|
|
INSERT INTO t1 VALUES (NULL, '', NULL);
|
|
INSERT INTO t1 VALUES (NULL, 'b', '');
|
|
INSERT INTO t1 VALUES (NULL, 'b', 'c');
|
|
INSERT INTO t1 VALUES (NULL, 'b', NULL);
|
|
INSERT INTO t1 VALUES (NULL, NULL, '');
|
|
INSERT INTO t1 VALUES (NULL, NULL, 'c');
|
|
INSERT INTO t1 VALUES (NULL, NULL, NULL);
|
|
SELECT LENGTH(a||b||c), a||b||c FROM t1 ORDER BY a,b,c;
|
|
LENGTH(a||b||c) a||b||c
|
|
NULL NULL
|
|
0
|
|
1 c
|
|
0
|
|
0
|
|
1 c
|
|
1 b
|
|
1 b
|
|
2 bc
|
|
0
|
|
0
|
|
1 c
|
|
0
|
|
0
|
|
1 c
|
|
1 b
|
|
1 b
|
|
2 bc
|
|
1 a
|
|
1 a
|
|
2 ac
|
|
1 a
|
|
1 a
|
|
2 ac
|
|
2 ab
|
|
2 ab
|
|
3 abc
|
|
SELECT LENGTH(CONCAT(a||b||c)), CONCAT(a||b||c) FROM t1 ORDER BY a,b,c;
|
|
LENGTH(CONCAT(a||b||c)) CONCAT(a||b||c)
|
|
NULL NULL
|
|
0
|
|
1 c
|
|
0
|
|
0
|
|
1 c
|
|
1 b
|
|
1 b
|
|
2 bc
|
|
0
|
|
0
|
|
1 c
|
|
0
|
|
0
|
|
1 c
|
|
1 b
|
|
1 b
|
|
2 bc
|
|
1 a
|
|
1 a
|
|
2 ac
|
|
1 a
|
|
1 a
|
|
2 ac
|
|
2 ab
|
|
2 ab
|
|
3 abc
|
|
DROP TABLE t1;
|