Before insert triggert in mysql - mysql

I am trying to use a trigger to insert the updated value to another table. I have two tables (table1 and table2).
I want to copy the new primary key of table1 to a non-primary key field in table2 in hexadecimal value. the primary key is integer type and the other field is varchar.
The code is as follows:
delimiter /
drop trigger if exists a /
create trigger a before insert on table1 for each row
begin
insert into table2 set table1ID= hex(new.id);
end /
insert into table1 set name='Ronnie';
But, the problem is when i insert into table1, the primary key will not be added to table2. it will add 0 instead.
These are the tables:
create table table1 (
id integer not null auto_increment primary key,
name varchar(45) not null
);
create table table2 (
id integer not null auto_increment primary key,
table1ID varchar(45) not null
);

Your trigger is "before insert", and the new generated id is not available yet. Change it to "after insert":
create trigger a after insert on table1 for each row
begin
insert into table2 (warehouseID) values (hex(new.id));
end /
Please see it here.

Related

MySQL database trigger does not work properly

I have two tables, table1 and table2. The SQL is like:
create table table1(
name varchar(100) PRIMARY key not null
);
create table table2(
id bigint PRIMARY key AUTO_INCREMENT,
username varchar(100) not null );
create trigger trigger_test
after insert
on table1
for each ROW
insert into table2 (username)
select new.name from table1;
Every time a row is inserted into table1, this row should also be inserted into table2 by the trigger I created. But after I insert string 'a' into table1, it seems right.
After I insert a second string 'b' into table1, the result appears wrong.
.
For the second time, the same row in table2. Then, I keep inserting rows into table1, the third time is like this:
I am stuck here because I cannot find a solution. Hope to get your help. Thanks in advance.
Your trigger should be either
create trigger trigger_test
after insert
on table1
for each ROW
insert into table2 (username)
values (new.name);
Or
create trigger trigger_test
after insert
on table1
for each ROW
insert into table2 (username)
select new.name from table1 where name = new.name;
Second option is not recomended. But added just to show you where the problem was

reset auto-increment each year with new prefix

I have an auto incremented field in my table. It should reset every new year 01/01 and then the prefix part should increment.
For example in 2016 my auto incremented field was A1,A2,A3..... etc but on 12:00 AM 2017 it should reset to B1 and go from there `(B1,B2,B3... etc), until Z when prefix should stop incrementing.
I created two tables... one for integer and one for varchar
CREATE TABLE t1
(
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY
);
CREATE TABLE t2
(
id VARCHAR(1) NOT NULL PRIMARY KEY DEFAULT '0', name VARCHAR(30)
);
and am creating a trigger
DELIMITER $$
CREATE TRIGGER tg1
BEFORE INSERT ON t1
FOR EACH ROW
BEGIN
INSERT INTO t2 VALUES (NULL);
SET NEW.id = CONCAT('A', LPAD(LAST_INSERT_ID(), 3, '0'));
END$$
DELIMITER ;
but am not sure how to involve date.
My db is mysql

How to make SQL Server 2008 table primary key auto increment with some prefix

The given query is in mysql format. I want same query in SQL Server 2008.
CREATE TABLE table1_seq
(
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY
);
CREATE TABLE table1
(
id VARCHAR(7) NOT NULL PRIMARY KEY DEFAULT '0', name VARCHAR(30)
);
Now the trigger
DELIMITER $$
CREATE TRIGGER tg_table1_insert
BEFORE INSERT ON table1
FOR EACH ROW
BEGIN
INSERT INTO table1_seq VALUES (NULL);
SET NEW.id = CONCAT('LHPL', LPAD(LAST_INSERT_ID(), 3, '0'));
END$$
DELIMITER ;
Then you just insert rows to table1
INSERT INTO Table1 (name)
VALUES ('Jhon'), ('Mark');
And you'll have
| ID | NAME |
------------------
| LHPL001 | Jhon |
| LHPL002 | Mark |
This may answer your question
-- create table with 'ABCD' as prefix, combining with identity column Id
CREATE TABLE dbo.Persons
(
Id int IDENTITY (1,1) NOT NULL
,PersonId AS ('ABCD' + CONVERT(varchar(20), Id)) PERSISTED NOT NULL PRIMARY KEY
,Name varchar(100)
);
GO
-- Do not specify calculated column when insert values into the table
INSERT INTO dbo.Persons (Name)
VALUES ('Person1'), ('Person2'), ('Person3');
GO
-- Display the records from the table
SELECT PersonId, Name
FROM dbo.Persons;
GO
This approach does not require to create a separate table and trigger, therefore efficient.
Hope this helps.

Ignore insert if exist in table in mysql?

I have 6 columns in my table:
Id | Name | Mail id | Gender | Contact Number | father name
while inserting a data into table i wanted to check condition like if Name,mailid,contact number already exists then insert should not happen else record should be inserted.
Can any one suggest how to check the condition while inserting a record.
IF NOT EXISTS (SELECT * FROM Table_Name WHERE Condition you are checking)
BEGIN
INSERT INTO ............. ---<----- Your Insert Statement.....
END
You can define an index on multiple columns, e.g.:
CREATE UNIQUE INDEX arbitrary_index_name ON table_name (Name, mailid, contactnumber);
I also faced similar situation, you can do this by adding unique constraint to your table and using 'insert ignore' statement to add data.
Create table statement:
CREATE TABLE Student (
Id INT PRIMARY KEY AUTO_INCREMENT,
NAME VARCHAR(50),
Mailid VARCHAR(50),
Gender CHAR,
contactnumber BIGINT,
fathername VARCHAR(50),
UNIQUE(NAME,Mailid,contactnumber));
Insert Ignore statement:
INSERT IGNORE INTO student(NAME, Mailid,Gender,contactnumber,fathername) VALUES('Shekhar', 's#s.com', 'M', 987654321, 'Joshi');

mysql Getting the same auto_increment value into another

This may have a really easy answer. I have done much database stuff for a while. I am trying to get the auto_increment value from one table inserted into the value on another table. is there an easy way of doing this. For eg i have done:
CREATE TABLE table_a (
id int NOT NULL AUTO_INCREMENT,
a_value varchar(4),
PRIMARY KEY (id)
);
CREATE TABLE table_b (
id int NOT NULL,
b_value varchar(15),
FOREIGN KEY (id) REFERENCES table_a (id)
);
Now i want to insert values into the table but I would like 'id' values for table_a and table_b to be the same. So far i have:
INSERT INTO table_a VALUES (NULL, 'foobar');
But I do not know how to go about extracting the auto_incermented 'id' number from table_a into the 'id' value of table_b. I have looked at SELECT #id = LAST_INSERT_ID() but can not get it to work.
You cannot do that at once. You'll have to first insert into the first table:
INSERT INTO table_a (a_value) VALUES ('foobar');
and then insert into the second using the generated id:
INSERT INTO table_b (id, b_value) VALUES (##IDENTITY, 'foobar');
LAST_INSERT_ID() and no need for the select statement part.