Using SQL Sub-queries in an INSERT Statement - mysql

Here are the two tables created:
CREATE TABLE category_tbl(
id int NOT NULL AUTO_INCREMENT,
name varchar(255) NOT NULL,
subcategory varchar(255) NOT NULL,
PRIMARY KEY(id),
CONSTRAINT nameSubcategory UNIQUE KEY(name, subcategory)
) ENGINE=InnoDB;
CREATE TABLE device(
id INT NOT NULL AUTO_INCREMENT,
cid INT DEFAULT NULL,
name VARCHAR(255) NOT NULL,
received DATE,
isbroken BOOLEAN,
PRIMARY KEY(id),
FOREIGN KEY(cid) REFERENCES category_tbl(id)
) ENGINE=InnoDB;
Below is the instruction that was given to me:
-- insert the following devices instances into the device table (you should use a subquery to set up foriegn keys referecnes, no hard coded numbers):
-- cid - reference to name: phone subcategory: maybe a tablet?
-- name - Samsung Atlas
-- received - 1/2/1970
-- isbroken - True
I'm getting errors on the insert statement below from attempting to use a sub-query within an insert statement. How would you solve this issue?
INSERT INTO devices(cid, name, received, isbroken)
VALUES((SELECT id FROM category_tbl WHERE subcategory = 'tablet') , 'Samsung Atlas', 1/2/1970, 'True');

You have different table name in CREATE TABLE and INSERT INTO so just choose one device or devices
When insert date format use the good one like DATE('1970-02-01')
When insert boolean - just TRUE with no qoutes I beleive.
http://sqlfiddle.com/#!9/b7180/1
INSERT INTO devices(cid, name, received, isbroken)
VALUES((SELECT id FROM category_tbl WHERE subcategory = 'tablet') , 'Samsung Atlas', DATE('1970-02-01'), TRUE);

It's not possible to use a SELECT in an INSERT ... VALUES ... statement. The key here is the VALUES keyword. (EDIT: It is actually possible, my bad.)
If you remove the VALUES keyword, you can use the INSERT ... SELECT ... form of the INSERT statement statement.
For example:
INSERT INTO mytable ( a, b, c) SELECT 'a','b','c'
In your case, you could run a query that returns the needed value of the foreign key column, e.g.
SELECT c.id
FROM category_tbl c
WHERE c.name = 'tablet'
ORDER BY c.id
LIMIT 1
If we add some literals in the SELECT list, like this...
SELECT c.id AS `cid`
, 'Samsung Atlas' AS `name`
, '1970-01-02' AS `received`
, 'True' AS `isBroken`
FROM category_tbl c
WHERE c.name = 'tablet'
ORDER BY c.id
LIMIT 1
That will return a "row" that we could insert. Just precede the SELECT with
INSERT INTO device (`cid`, `name`, `received`, `isbroken`)
NOTE: The expressions returned by the SELECT are "lined up" with the columns in the column list by position, not by name. The aliases assigned to the expressions in the SELECT list are arbitrary, they are basically ignored. They could be omitted, but I think having the aliases assigned makes it easier to understand when we run just the SELECT portion.

Related

I unable to Insert a value from a char that has been CAST as Integer and added by 1

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');

MySQL : IF EXISTS THEN UPDATE ELSE INSERT from one table to another using IF ELSE statement

I have two tables user & user_tmp having primary key as id only. The fields of both the tables are likely as :
`id` PRIMARY AUTO_INCREMENT INT,
`Name` VARCHAR(80),
`Contact No` VARCHAR(10),
`Status` INT
I need a simple query based on IF EXISTS ON user_tmp table THEN update value in user ELSE insert in user table.
I tried with REPLACE & ON DUPLICATE KEY, but it din't work as id is the PRIMARY KEY and the value varies in both the tables.
Regards.
You need to do it as two queries. One query to update the records that match:
UPDATE user AS u
JOIN user_tmp AS t ON u.Contact_No = t.Contact_no
SET u.Name = t.Name, u.Status = t.Status;
and a second to insert the ones that don't already exist:
INSERT INTO user (Name, Contact_No, Status)
SELECT t.Name, t.Contact_No, t.Status
FROM user_tmp AS t
LEFT JOIN user AS u ON u.Contact_No = t.Contact_no
WHERE t.id IS NULL
See Return row only if value doesn't exist for an explanation of how the SELECT query in the INSERT works to find rows that don't match.

How to use INSERT ... SELECT with a particular column auto-incrementing, starting at 1?

I am using INSERT ... SELECT to insert a data from specific columns from specific rows from a view into a table. Here's the target table:
CREATE TABLE IF NOT EXISTS `queue` (
`ID` int(11) NOT NULL AUTO_INCREMENT,
`customerId` int(11) NOT NULL,
`productId` int(11) NOT NULL,
`priority` int(11) NOT NULL,
PRIMARY KEY (`ID`),
KEY `customerId` (`customerId`),
KEY `productId` (`productId`),
KEY `priority` (`priority`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 ;
The INSERT ... SELECT SQL I have works, but I would like to improve it if possible, as follows: I would like the inserted rows to start with 1 in the priority column, and each subsequent row to increment the priority value by 1. So, if three rows were inserted, the first would be priority 1, the second 2, and the third 3.
A exception to the "start at 1" rule: if there are existing rows in the target table for the specified customer, I would like the inserted rows to start with MAX(priority)+1 for that customer.
I thought I could use a subquery, but here's the problem: sometimes the subquery returns NULL (when there are no records in the queue table for the specified customer), which breaks the insert, as the priority column does not allow nulls.
I tried to CAST the column to an integer, but that still gave me NULL back when there are no records with that customer ID in the table.
I've hardcoded the customer ID in this example, but naturally in my application that would be an input parameter.
INSERT INTO `queue`
(
`customerId`,
`productId`,
`priority`,
`status`,
`orderId`)
SELECT
123, -- This is the customer ID
`PRODUCT_NO`,
(SELECT (MAX(`priority`)+1) FROM `queue` WHERE `customerId` = 123),
'queued',
null
FROM
`queue_eligible_products_view`
Is there a way to do this in one SQL statement, or a small number of SQL statements, i.e., less than SQL statement per row?
I do not think I can set the priority column to auto_increment, as this column is not necessarily unique, and the auto_increment attribute is used to generate a unique identity for new rows.
As Barmar mentions in the comments : use IFNULL to handle your sub query returning null. Hence:
INSERT INTO `queue`
(
`customerId`,
`productId`,
`priority`,
`status`,
`orderId`)
SELECT
123, -- This is the customer ID
`PRODUCT_NO`,
IFNULL((SELECT (MAX(`priority`)+1) FROM `queue` WHERE `customerId` = 123),1),
'queued',
null
FROM
`queue_eligible_products_view`
Here's how to do the incrementing:
INSERT INTO queue (customerId, productId, priority, status, orderId)
SELECT 123, product_no, #priority := #priority + 1, 'queued', null
FROM queue_eligible_products_view
JOIN (SELECT #priority := IFNULL(MAX(priority), 0)
FROM queue
WHERE customerId = 123) var

Mysql query to get detail of comma-separated ids data

I have 2 tables, items and members :
CREATE TABLE IF NOT EXISTS `items` (
`id` int(5) NOT NULL AUTO_INCREMENT,
`name` varchar(255) NOT NULL,
`member` varchar(255) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE IF NOT EXISTS `members` (
`id` int(5) NOT NULL AUTO_INCREMENT,
`name` varchar(255) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
What if, for example I have a record inside items, such as
INSERT INTO `test`.`items` (
`id` ,
`name` ,
`member`
)
VALUES (
NULL , 'xxxx', '1, 2, 3'
);
in members :
INSERT INTO `members` (`id`, `name`) VALUES
(1, 'asdf'),
(2, 'qwert'),
(3, 'uiop'),
(4, 'jkl;');
and I'd like to display items.member data with members.name, something like 1#asdf, 2#qwert, 3#uiop??
I've tried the following query,
SELECT items.id, items.name, GROUP_CONCAT(CONCAT_WS('#', members.id, members.name) ) as member
FROM `items`
LEFT JOIN members AS members on (members.id = items.member)
WHERE items.id = 1
But the result is not like I expected. Is there any other way to display the data via one call query? Because I'm using PHP, right now, i'm explode items.member and loop it one by one, to display the members.name.
You could look into using FIND_IN_SET() in your join criteria:
FROM items JOIN members ON FIND_IN_SET(members.id, items.member)
However, note from the definition of FIND_IN_SET():
A string list is a string composed of substrings separated by “,” characters.
Therefore the items.member column should not contain any spaces (I suppose you could use FIND_IN_SET(members.id, REPLACE(items.member, ' ', '')) - but this is going to be extremely costly as your database grows).
Really, you should normalise your schema:
CREATE TABLE memberItems (
item_id INT(5) NOT NULL,
member_id INT(5) NOT NULL,
FOREIGN KEY item_id REFERENCES items (id),
FOREIGN KEY member_id REFERENCES members (id)
);
INSERT INTO memberItems
(item_id, member_id)
SELECT items.id, members.id
FROM items
JOIN members ON FIND_IN_SET(members.id, REPLACE(items.member,' ',''))
;
ALTER TABLE items DROP member;
This is both index-friendly (and therefore can be queried very efficiently) and has the database enforce referential integrity.
Then you can do:
FROM items JOIN memberItems ON memberItems.item_id = items.id
JOIN members ON members.id = memberItems.member_id
Note also that it's generally unwise to use GROUP_CONCAT() to combine separate records into a string in this fashion: your application should instead be prepared to loop over the resultset to fetch each member.
Please take a look at this sample:
SQLFIDDLE
Your query seems to work for what you have mentioned in the question... :)
SELECT I.ID, I.ITEM,
GROUP_CONCAT(CONCAT("#",M.ID,
M.NAME, " ")) AS MEMB
FROM ITEMS AS I
LEFT JOIN MEMBERS AS M
ON M.ID = I.MID
WHERE i.id = 1
;
EDITTED ANSWER
This query will not work for you¬ as your schema doesn't seem to have any integrity... or proper references. Plus your memeber IDs are delimtted by a comma, which has been neglected in this answer.

Insert and set value with max()+1 problems

I am trying to insert a new row and set the customer_id with max()+1. The reason for this is the table already has a auto_increatment on another column named id and the table will have multiple rows with the same customer_id.
With this:
INSERT INTO customers
( customer_id, firstname, surname )
VALUES
((SELECT MAX( customer_id ) FROM customers) +1, 'jim', 'sock')
...I keep getting the following error:
#1093 - You can't specify target table 'customers' for update in FROM clause
Also how would I stop 2 different customers being added at the same time and not having the same customer_id?
You can use the INSERT ... SELECT statement to get the MAX()+1 value and insert at the same time:
INSERT INTO
customers( customer_id, firstname, surname )
SELECT MAX( customer_id ) + 1, 'jim', 'sock' FROM customers;
Note: You need to drop the VALUES from your INSERT and make sure the SELECT selected fields match the INSERT declared fields.
Correct, you can not modify and select from the same table in the same query. You would have to perform the above in two separate queries.
The best way is to use a transaction but if your not using innodb tables then next best is locking the tables and then performing your queries. So:
Lock tables customers write;
$max = SELECT MAX( customer_id ) FROM customers;
Grab the max id and then perform the insert
INSERT INTO customers( customer_id, firstname, surname )
VALUES ($max+1 , 'jim', 'sock')
unlock tables;
Use alias name for the inner query like this
INSERT INTO customers
( customer_id, firstname, surname )
VALUES
((SELECT MAX( customer_id )+1 FROM customers cust), 'sharath', 'rock')
SELECT MAX(col) +1 is not safe -- it does not ensure that you aren't inserting more than one customer with the same customer_id value, regardless if selecting from the same table or any others. The proper way to ensure a unique integer value is assigned on insertion into your table in MySQL is to use AUTO_INCREMENT. The ANSI standard is to use sequences, but MySQL doesn't support them. An AUTO_INCREMENT column can only be defined in the CREATE TABLE statement:
CREATE TABLE `customers` (
`customer_id` int(11) NOT NULL AUTO_INCREMENT,
`firstname` varchar(45) DEFAULT NULL,
`surname` varchar(45) DEFAULT NULL,
PRIMARY KEY (`customer_id`)
)
That said, this worked fine for me on 5.1.49:
CREATE TABLE `customers` (
`customer_id` int(11) NOT NULL DEFAULT '0',
`firstname` varchar(45) DEFAULT NULL,
`surname` varchar(45) DEFAULT NULL,
PRIMARY KEY (`customer_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1$$
INSERT INTO customers VALUES (1, 'a', 'b');
INSERT INTO customers
SELECT MAX(customer_id) + 1, 'jim', 'sock'
FROM CUSTOMERS;
insert into table1(id1) select (max(id1)+1) from table1;
Use table alias in subquery:
INSERT INTO customers
( customer_id, firstname, surname )
VALUES
((SELECT MAX( customer_id ) FROM customers C) +1, 'jim', 'sock')
None of the about answers works for my case. I got the answer from here, and my SQL is:
INSERT INTO product (id, catalog_id, status_id, name, measure_unit_id, description, create_time)
VALUES (
(SELECT id FROM (SELECT COALESCE(MAX(id),0)+1 AS id FROM product) AS temp),
(SELECT id FROM product_catalog WHERE name="AppSys1"),
(SELECT id FROM product_status WHERE name ="active"),
"prod_name_x",
(SELECT id FROM measure_unit WHERE name ="unit"),
"prod_description_y",
UNIX_TIMESTAMP(NOW())
)
Your sub-query is just incomplete, that's all. See the query below with my additions:
INSERT INTO customers ( customer_id, firstname, surname )
VALUES ((SELECT MAX( customer_id ) FROM customers) +1), 'jim', 'sock')
You can't do it in a single query, but you could do it within a transaction. Do the initial MAX() select and lock the table, then do the insert. The transaction ensures that nothing will interrupt the two queries, and the lock ensures that nothing else can try doing the same thing elsewhere at the same time.
We declare a variable 'a'
SET **#a** = (SELECT MAX( customer_id ) FROM customers) +1;
INSERT INTO customers
( customer_id, firstname, surname )
VALUES
(**#a**, 'jim', 'sock')
This is select come insert sequel.
I am trying to get serial_no maximum +1 value and its giving correct value.
SELECT MAX(serial_no)+1 into #var FROM sample.kettle;
Insert into kettle(serial_no,name,age,salary) values (#var,'aaa',23,2000);