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drop table if exists t1, t2;
drop view if exists v1;
create table t1 (i int);
create trigger trg before insert on t1 for each row set @a:=1;
set @a:=0;
select @a;
@a
0
insert into t1 values (1);
select @a;
@a
1
drop trigger t1.trg;
create trigger trg before insert on t1 for each row set @a:=new.i;
insert into t1 values (123);
select @a;
@a
123
drop trigger t1.trg;
drop table t1;
create table t1 (i int not null, j int);
create trigger trg before insert on t1 for each row
begin
if isnull(new.j) then
set new.j:= new.i * 10;
end if;
end|
insert into t1 (i) values (1)|
insert into t1 (i,j) values (2, 3)|
select * from t1|
i j
1 10
2 3
drop trigger t1.trg|
drop table t1|
create table t1 (i int not null primary key);
create trigger trg after insert on t1 for each row
set @a:= if(@a,concat(@a, ":", new.i), new.i);
set @a:="";
insert into t1 values (2),(3),(4),(5);
select @a;
@a
2:3:4:5
drop trigger t1.trg;
drop table t1;
create table t1 (aid int not null primary key, balance int not null default 0);
insert into t1 values (1, 1000), (2,3000);
create trigger trg before update on t1 for each row
begin
declare loc_err varchar(255);
if abs(new.balance - old.balance) > 1000 then
set new.balance:= old.balance;
set loc_err := concat("Too big change for aid = ", new.aid);
set @update_failed:= if(@update_failed, concat(@a, ":", loc_err), loc_err);
end if;
end|
set @update_failed:=""|
update t1 set balance=1500|
select @update_failed;
select * from t1|
@update_failed
Too big change for aid = 2
aid balance
1 1500
2 3000
drop trigger t1.trg|
drop table t1|
create table t1 (i int);
insert into t1 values (1),(2),(3),(4);
create trigger trg after update on t1 for each row
set @total_change:=@total_change + new.i - old.i;
set @total_change:=0;
update t1 set i=3;
select @total_change;
@total_change
2
drop trigger t1.trg;
drop table t1;
create table t1 (i int);
insert into t1 values (1),(2),(3),(4);
create trigger trg before delete on t1 for each row
set @del_sum:= @del_sum + old.i;
set @del_sum:= 0;
delete from t1 where i <= 3;
select @del_sum;
@del_sum
6
drop trigger t1.trg;
drop table t1;
create table t1 (i int);
insert into t1 values (1),(2),(3),(4);
create trigger trg after delete on t1 for each row set @del:= 1;
set @del:= 0;
delete from t1 where i <> 0;
select @del;
@del
1
drop trigger t1.trg;
drop table t1;
create table t1 (i int, j int);
create trigger trg1 before insert on t1 for each row
begin
if new.j > 10 then
set new.j := 10;
end if;
end|
create trigger trg2 before update on t1 for each row
begin
if old.i % 2 = 0 then
set new.j := -1;
end if;
end|
create trigger trg3 after update on t1 for each row
begin
if new.j = -1 then
set @fired:= "Yes";
end if;
end|
set @fired:="";
insert into t1 values (1,2),(2,3),(3,14);
select @fired;
@fired
select * from t1;
i j
1 2
2 3
3 10
update t1 set j= 20;
select @fired;
@fired
Yes
select * from t1;
i j
1 20
2 -1
3 20
drop trigger t1.trg1;
drop trigger t1.trg2;
drop trigger t1.trg3;
drop table t1;
create table t1 (i int);
create trigger trg before insert on t1 for each row set @a:= old.i;
ERROR HY000: There is no OLD row in on INSERT trigger
create trigger trg before delete on t1 for each row set @a:= new.i;
ERROR HY000: There is no NEW row in on DELETE trigger
create trigger trg before update on t1 for each row set old.i:=1;
ERROR HY000: Updating of OLD row is not allowed in trigger
create trigger trg before delete on t1 for each row set new.i:=1;
ERROR HY000: There is no NEW row in on DELETE trigger
create trigger trg after update on t1 for each row set new.i:=1;
ERROR HY000: Updating of NEW row is not allowed in after trigger
create trigger trg before update on t1 for each row set new.j:=1;
ERROR 42S22: Unknown column 'j' in 'NEW'
create trigger trg before update on t1 for each row set @a:=old.j;
ERROR 42S22: Unknown column 'j' in 'OLD'
create trigger trg before insert on t2 for each row set @a:=1;
ERROR 42S02: Table 'test.t2' doesn't exist
create trigger trg before insert on t1 for each row set @a:=1;
create trigger trg after insert on t1 for each row set @a:=1;
ERROR HY000: Trigger already exists
create trigger trg2 before insert on t1 for each row set @a:=1;
ERROR HY000: Trigger already exists
drop trigger t1.trg;
drop trigger t1.trg;
ERROR HY000: Trigger does not exist
create view v1 as select * from t1;
create trigger trg before insert on v1 for each row set @a:=1;
ERROR HY000: Trigger's 'v1' is view or temporary table
drop view v1;
drop table t1;
create temporary table t1 (i int);
create trigger trg before insert on t1 for each row set @a:=1;
ERROR HY000: Trigger's 't1' is view or temporary table
drop table t1;
create table t1 (x1col char);
create trigger tx1 before insert on t1 for each row set new.x1col = 'x';
insert into t1 values ('y');
drop trigger t1.tx1;
drop table t1;
create table t1 (i int) engine=myisam;
insert into t1 values (1), (2);
create trigger trg1 before delete on t1 for each row set @del_before:= @del_before + old.i;
create trigger trg2 after delete on t1 for each row set @del_after:= @del_after + old.i;
set @del_before:=0, @del_after:= 0;
delete from t1;
select @del_before, @del_after;
@del_before @del_after
3 3
drop trigger t1.trg1;
drop trigger t1.trg2;
drop table t1;
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