1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
|
drop table if exists t1,t2,t3;
create table t1(id1 int not null auto_increment primary key, t char(12));
create table t2(id2 int not null, t char(12));
create table t3(id3 int not null, t char(12), index(id3));
select count(*) from t1 where id1 > 95;
count(*)
5
select count(*) from t2 where id2 > 95;
count(*)
25
select count(*) from t3 where id3 > 95;
count(*)
250
update t1,t2,t3 set t1.t="aaa", t2.t="bbb", t3.t="cc" where t1.id1 = t2.id2 and t2.id2 = t3.id3 and t1.id1 > 90;
select count(*) from t1 where t = "aaa";
count(*)
10
select count(*) from t1 where id1 > 90;
count(*)
10
select count(*) from t2 where t = "bbb";
count(*)
50
select count(*) from t2 where id2 > 90;
count(*)
50
select count(*) from t3 where t = "cc";
count(*)
500
select count(*) from t3 where id3 > 90;
count(*)
500
delete t1.*, t2.*, t3.* from t1,t2,t3 where t1.id1 = t2.id2 and t2.id2 = t3.id3 and t1.id1 > 95;
check table t1, t2, t3;
Table Op Msg_type Msg_text
test.t1 check status OK
test.t2 check status OK
test.t3 check status OK
select count(*) from t1 where id1 > 95;
count(*)
0
select count(*) from t2 where id2 > 95;
count(*)
0
select count(*) from t3 where id3 > 95;
count(*)
0
delete t1, t2, t3 from t1,t2,t3 where t1.id1 = t2.id2 and t2.id2 = t3.id3 and t1.id1 > 5;
select count(*) from t1 where id1 > 5;
count(*)
0
select count(*) from t2 where id2 > 5;
count(*)
0
select count(*) from t3 where id3 > 5;
count(*)
0
delete from t1, t2, t3 using t1,t2,t3 where t1.id1 = t2.id2 and t2.id2 = t3.id3 and t1.id1 > 0;
select count(*) from t1 where id1;
count(*)
0
select count(*) from t2 where id2;
count(*)
0
select count(*) from t3 where id3;
count(*)
0
drop table t1,t2,t3;
create table t1(id1 int not null primary key, t varchar(100)) pack_keys = 1;
create table t2(id2 int not null, t varchar(100), index(id2)) pack_keys = 1;
delete t1 from t1,t2 where t1.id1 = t2.id2 and t1.id1 > 500;
drop table t1,t2;
CREATE TABLE t1 (
id int(11) NOT NULL default '0',
name varchar(10) default NULL,
PRIMARY KEY (id)
) TYPE=MyISAM;
INSERT INTO t1 VALUES (1,'aaa'),(2,'aaa'),(3,'aaa');
CREATE TABLE t2 (
id int(11) NOT NULL default '0',
name varchar(10) default NULL,
PRIMARY KEY (id)
) TYPE=MyISAM;
INSERT INTO t2 VALUES (2,'bbb'),(3,'bbb'),(4,'bbb');
CREATE TABLE t3 (
id int(11) NOT NULL default '0',
mydate datetime default NULL,
PRIMARY KEY (id)
) TYPE=MyISAM;
INSERT INTO t3 VALUES (1,'2002-02-04 00:00:00'),(3,'2002-05-12 00:00:00'),(5,'2002-05-12 00:00:00'),(6,'2002-06-22
00:00:00'),(7,'2002-07-22 00:00:00');
delete t1,t2,t3 from t1,t2,t3 where to_days(now())-to_days(t3.mydate)>=30 and t3.id=t1.id and t3.id=t2.id;
select * from t3;
id mydate
1 2002-02-04 00:00:00
5 2002-05-12 00:00:00
6 2002-06-22 00:00:00
7 2002-07-22 00:00:00
DROP TABLE IF EXISTS t1,t2,t3;
CREATE TABLE IF NOT EXISTS `t1` (
`id` int(11) NOT NULL auto_increment,
`tst` text,
`tst1` text,
PRIMARY KEY (`id`)
) TYPE=MyISAM;
CREATE TABLE IF NOT EXISTS `t2` (
`ID` int(11) NOT NULL auto_increment,
`ParId` int(11) default NULL,
`tst` text,
`tst1` text,
PRIMARY KEY (`ID`),
KEY `IX_ParId_t2` (`ParId`),
FOREIGN KEY (`ParId`) REFERENCES `t1` (`id`)
) TYPE=MyISAM;
INSERT INTO t1(tst,tst1) VALUES("MySQL","MySQL AB"), ("MSSQL","Microsoft"), ("ORACLE","ORACLE");
INSERT INTO t2(ParId) VALUES(1), (2), (3);
select * from t2;
ID ParId tst tst1
1 1 NULL NULL
2 2 NULL NULL
3 3 NULL NULL
UPDATE t2, t1 SET t2.tst = t1.tst, t2.tst1 = t1.tst1 WHERE t2.ParId = t1.Id;
select * from t2;
ID ParId tst tst1
1 1 MySQL MySQL AB
2 2 MSSQL Microsoft
3 3 ORACLE ORACLE
drop table if exists t1, t2 ;
create table t1 (n numeric(10));
create table t2 (n numeric(10));
insert into t2 values (1),(2),(4),(8),(16),(32);
select * from t2 left outer join t1 using (n);
n n
1 NULL
2 NULL
4 NULL
8 NULL
16 NULL
32 NULL
delete t1,t2 from t2 left outer join t1 using (n);
select * from t2 left outer join t1 using (n);
n n
drop table t1,t2 ;
create table t1 (n int(10) not null primary key, d int(10));
create table t2 (n int(10) not null primary key, d int(10));
insert into t1 values(1,1);
insert into t2 values(1,10),(2,20);
LOCK TABLES t1 write, t2 read;
DELETE t1.*, t2.* FROM t1,t2 where t1.n=t2.n;
Table 't2' was locked with a READ lock and can't be updated
UPDATE t1,t2 SET t1.d=t2.d,t2.d=30 WHERE t1.n=t2.n;
Table 't2' was locked with a READ lock and can't be updated
UPDATE t1,t2 SET t1.d=t2.d WHERE t1.n=t2.n;
Table 't2' was locked with a READ lock and can't be updated
unlock tables;
LOCK TABLES t1 write, t2 write;
UPDATE t1,t2 SET t1.d=t2.d WHERE t1.n=t2.n;
select * from t1;
n d
1 10
DELETE t1.*, t2.* FROM t1,t2 where t1.n=t2.n;
select * from t1;
n d
select * from t2;
n d
2 20
unlock tables;
drop table t1,t2;
|
