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.
Related
I have a question for an assignment with 5 tables as shown below. I need to write a query with the minimum cost for each sport:
2nd column is equipment_name:
I think I need to do a bunch of joins in subqueries with the primary keys being the id columns and the foreign keys the name_id columns. Is this the right approach?
You don't need a bunch of joins; minimally this question can be solved by one join between the store_equipment_price and the sports_equipment tables - if these two are joined on equipment id then you'll effectively get rows that can give the cost of starting up in each sport per store. You'll need to group by the sport id and the store id; don't forget that it might be cheaper to start soccer by getting all the gear from store A but it might be cheaper to start golf by going to tore B - tho I how I read the question. If however you're prepared to get your gloves from store A and your bat from store B etc then we don't even group by the store when summing, instead we work out which store is cheapest for each component rather than which store is cheapest for each sport overall.
If you're after producing named stores/sports on your result rows then you'll need more joins but try getting the results right based on the fewest number of joins possible to start with
Both these queries will ultimately be made a lot easier by the use of an analytic/windowing function but these are database dependent; never post an sql question up without stating what your db vendor is, as there are few questions that are pure ISO SQL
You question is not completely clear, I assume you need to find stores from which to buy each equipment for all sports so as to incur minimum expense. Following query will achieve this
select s.sports, e.equipment_name, min(sep.price),
(select store_name from stores st where st.id = sep.store_id) store_name
from sports s
join sports_equipment se on s.id = se.sport_id
join equipment e on e.id = se.equipment_id
join sports_equipment_prices sep on sep.equipment_id = se.equipment_id
group by s.sports, e.equipment_name
order by s.sports, e.equipment_name
;
Following 'create table' and 'insert data' script are based on your screen images
create table sports (
id INTEGER PRIMARY KEY AUTOINCREMENT,
sports varchar(50)
);
insert into sports(sports) values('golf');
insert into sports(sports) values('baseball');
insert into sports(sports) values('soccer');
create table stores (
id INTEGER PRIMARY KEY AUTOINCREMENT,
store_name varchar(50)
);
insert into stores(store_name) values('A');
insert into stores(store_name) values('B');
insert into stores(store_name) values('C');
create table equipment (
id INTEGER PRIMARY KEY AUTOINCREMENT,
equipment_name varchar(50)
);
insert into equipment(equipment_name) values('shoes');
insert into equipment(equipment_name) values('ball');
insert into equipment(equipment_name) values('clubs');
insert into equipment(equipment_name) values('glove');
insert into equipment(equipment_name) values('bat');
create table sports_equipment (
sport_id INTEGER not null,
equipment_id INTEGER not null,
FOREIGN KEY(sport_id) REFERENCES sports(id),
FOREIGN KEY(equipment_id) REFERENCES equipment(id)
);
insert into sports_equipment values(1, 1);
insert into sports_equipment values(1, 2);
insert into sports_equipment values(1, 3);
insert into sports_equipment values(2, 2);
insert into sports_equipment values(2, 4);
insert into sports_equipment values(2, 5);
insert into sports_equipment values(3, 1);
insert into sports_equipment values(3, 2);
create table sports_equipment_prices (
id INTEGER PRIMARY KEY AUTOINCREMENT,
store_id INTEGER not null,
equipment_id INTEGER not null,
price INTEGER not null,
FOREIGN KEY(store_id) REFERENCES stores(id),
FOREIGN KEY(equipment_id) REFERENCES equipment(id)
);
I convert an id which is in a char column datatype. after that, I want to add it by 1 (plus 1).
Could you help me? why my query is not working?
query:
INSERT INTO `countries` (`id`, `country_name`) VALUES ((SELECT MAX(CAST(`id` as INTEGER)) AS `max_id` FROM `countries`) + 1, 'India');
The following would run:
INSERT INTO `countries` (`id`, `country_name`)
SELECT MAX(CAST(`id` as INTEGER)) + 1, 'India'
FROM `countries`;
But I think it would be easier if you just make the id column an AUTO_INCREMENT.
This is not how you should be doing identifiers.
If you want incrementing id values, you want to use the AUTO_INCREMENT feature when creating your table.
Your way is dangerous, there's always a possibility of two transactions running at the same time picking the same "next ID".
Just create a table with the flag on:
CREATE TABLE countries (
id MEDIUMINT NOT NULL AUTO_INCREMENT,
name CHAR(30) NOT NULL,
PRIMARY KEY (id)
);
INSERT INTO countries (`name`) VALUES ('India');
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.
I've got an INSERT ... ON DUPLICATE KEY UPDATE query and I am trying to add WHERE clause to it:
INSERT INTO `product_description` (
`product_id`,`language_id`,`name`,
`description`,`meta_description`,
`meta_keyword`,`tag`
) VALUES (
$getProductId, $languageId, '$pName', '$pDescription', '', '', ''
)
ON DUPLICATE KEY UPDATE
`name` = '$pName',
`description` = '$pDescription'
I want to restrict the UPDATE to those 2 conditions:
WHERE `model` = 'specific-model' AND `sku` NOT LIKE '%B15%'
If I add this part of query to the end of the original query I get a MySQL syntax error. What would be a working solution?
Update: Please note that model and sku are in another table, and the common key is product_id
I would suggest you to use some sort of prepared statement instead of concatenating strings, so you should do something like this:
INSERT INTO `product_description` (
`product_id`, `language_id`, `name`,
`description`, `meta_description`,
`meta_keyword`, `tag`
) VALUES (?, ?, ?, ?,'','','')
but this is not part of the question.
I was thinking of answering with a simple CASE WHEN but the challenging part of your question is that the restrict conditions are not in the product_description table but are from another table. So I think we can just use a TRIGGER:
CREATE TRIGGER product_description_upd
BEFORE UPDATE ON product_description
FOR EACH ROW
IF NOT EXISTS(SELECT * FROM models
WHERE product_id=new.product_id
AND model='Abc' AND `sku` NOT LIKE '%B15%') THEN
SET new.name=old.name;
SET new.description=old.description;
END IF;
//
then you can use an INSERT query like:
INSERT INTO `product_description` (col1, col2, ...)
VALUES (..., ..., ...)
ON DUPLICATE KEY
UPDATE name=VALUE(name),description=VALUE(description)
Please see a fiddle here.
The only thing to note here is that even a standard UPDATE query will be affected.
CREATE TABLE product_description (
product_id INT PRIMARY KEY,
name VARCHAR(100),
description VARCHAR(100)
);
CREATE TABLE models (
product_id INT,
model VARCHAR(100),
sku VARCHAR(100)
);
INSERT INTO models VALUES
(1, "Abc", "ZZZ"),
(2, "Abc", "B15");
INSERT INTO product_description VALUES
(1, "Car", "Red"),
(2, "Truck", "Pink");
INSERT INTO `product_description` VALUES (1, "NewCar", "DeepRed")
ON DUPLICATE KEY UPDATE name=VALUES(name), description=VALUES(description);
Assuming, product_id must be in models.
INSERT INTO `product_description` (product_id, name, description)
SELECT models.product_id, "SuperCar" as name, "DarkRed" as description
FROM `models` WHERE model="Abc" AND `sku` NOT LIKE "%B15%"
ON DUPLICATE KEY UPDATE name="UpdatedCar", description="UpdatedRed";
refer to http://sqlfiddle.com/#!9/69624e/1
Hopefully this solves the problem. You can play with SELECT query for different result.
CREATE TABLE IF NOT EXISTS `MyTable` (
`ID` SMALLINT NOT NULL AUTO_INCREMENT,
`Name` VARCHAR(50) NOT NULL,
PRIMARY KEY (`ID`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
INSERT INTO MyTable (ID,Name) VALUES (ID=4,Name='xxx')
or
INSERT INTO MyTable (Name) VALUES (Name='xxx')
The problem is that both INSERT statements produce the entry (4,0). Why 0 instead of "xxx"?
UPDATE: Primary key changed.
This should do the job :
INSERT INTO MyTable (ID, Name) VALUES (4, 'xxx')
I'm pretty sure it would be something like this, instead...
INSERT INTO MyTable (Name) VALUES ('xxx')
No need for the Name= part, since you've already specified which column you wish to insert into with the first (Name) definition.
Because the expression Name='xxx' is false, hence evaluates as zero.
You use the column=expression method use in on duplicate key update clauses as described here, not in the "regular" section of inserts. An example of that:
insert into mytable (col1,col2) values (1,2)
on duplicate key update col1 = col1 + 1
You should be using the syntax:
INSERT INTO MyTable (ID,Name) VALUES (4,'xxx')
Is that syntax of Name='xxx' valid? Never seen it before, i assume it is seeing it as an unquoted literal, trying to convert it to a number and coming up with 0? I'm not sure at all
Try this:
INSERT INTO MyTable (Name) VALUES ('xxx')
This is because you should mention the name of the column in the values part. And also because you do not define you primary key correctly (airlineID is not part of the field list)
CREATE TABLE IF NOT EXISTS `MyTable` (
`ID` SMALLINT NOT NULL AUTO_INCREMENT,
`Name` VARCHAR(50) NOT NULL,
PRIMARY KEY (`ID`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
INSERT INTO MyTable (ID,Name) VALUES (4,'xxx')
INSERT INTO MyTable (Name) VALUES ('xxx')
Try this
INSERT INTO MyTable (ID,Name) VALUES (4,xxx)
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