I have a data set that looks like this:
id | Unit_Ids
1 | {"unit_ids" : ["5442","28397"]}
2 | {"unit_ids" : ["5442","3492","2290"]}
etc.
And I'm trying to find the most frequently appearing values in Unit_Ids. As in my example 5442 appears in both lines 1 and 2, it would be the most frequent value. I was just having trouble finding a good way of creating this statement.
Thank you in advanced!
EDIT: Sorry everyone I'm working with MySQL
If 2016+
Example
Declare #YourTable Table ([id] int,[Unit_Ids] varchar(max))
Insert Into #YourTable Values
(1,'{"unit_ids" : ["5442","28397"]}')
,(2,'{"unit_ids" : ["5442","3492","2290"]}')
Select top 1 value
From #YourTable A
Cross Apply OpenJSON([Unit_Ids],'$.unit_ids') R
Order By sum(1) over (partition by value) desc
Returns
value
5442
I'm assuming you are storing JSON strings in the Unit_Ids field. If you do that, you won't be able to extract or aggregate data stored in that field.
You can however create a child table and query it to get aggregated data. Ie:
-- Master table
create table parent(id number primary key);
-- List of units per parent
create table units(
id number not null,
parent_id number not null,
primary key (id, parent_id),
foreign key (parent_id) references parent(id)
);
-- Insert sample data
insert into parent values 1;
insert into parent values 2;
insert into units(parent_id, id) values(1, 5442);
insert into units(parent_id, id) values(1, 28397);
insert into units(parent_id, id) values(2, 5442);
insert into units(parent_id, id) values(2, 3492);
insert into units(parent_id, id) values(2, 2290);
-- Count the number of times a unit id is in the table
select id, count(id) from units group by id;
Related
I want to insert a row if it's one specific column value is not still available. If available, i want to update that row. Otherwise it will insert normally. What should be the SQL query for this task?
For example:
id, Product_id, user_id, quantity are the table's attributes
Considering,
[1, 450, 56, 2] is in table.
If i want to insert [2,450,56,3] then it will not create new row. It will update the previous row. Like [1,450,56,5].
I'd start by creating a unique constraint on the combination of product_id and user_id (or even a primary key if you don't have one on the table yet):
ALTER TABLE mytable
ADD CONSTRAINT uc_product_user UNIQUE (product_id, user_id);
And then you can use the on duplicate clause in an insert statement:
INSERT INTO mytable
VALUES (2, 450, 56, 3)
ON DUPLICATE KEY UPDATE quantity = quantity + VALUES(quantity);
You could set product_id and user_id as the primary key or unique key on the table and then use INSERT .. ON DUPLICATE KEY UPDATE. You can find more information about that here.
It would look something like:
INSERT INTO t1 (id, product_id, user_id, quantity) VALUES (2,450,56,3)
ON DUPLICATE KEY UPDATE quantity = quantity + 3;
Alternatively, you're going to have to write your own merge statement (MySql doesn't support merge, but you can fake it)
DELIMITER $$
CREATE DEFINER=`root`#`localhost` PROCEDURE `sp_updateValue`(IN prm_productid INT, IN prm_userid INT, IN prm_quantity INT)
BEGIN
-- Check that the case actually exists first.
DECLARE vExists INT;
SELECT COUNT(1) INTO vExists FROM YourTable WHERE product_id = prm_orderid AND user_id = prm_userid;
IF vCaseExists = 1 THEN
UPDATE YourTable SET quantity = prm_quantity WHERE product_id = prm_orderid AND user_id = prm_userid;
ELSE
INSERT INTO YourTable (id, product_id, user_id, quantity) VALUES (2,450,56,3);
END IF;
END$$
DELIMITER ;
I've got the following table:
productId price
1 price_value1
2 price_value2
3 price_value3
I would like to insert a new product into the table and assign it a new productId. In this case its value equals to 4.
So I want my new table to look like so:
productId price
1 price_value1
2 price_value2
3 price_value3
4 price_value4
So as far as I understand, in order to do that I have to somehow retrieve the max value of productId and insert it using INSERT INTO mytable VALUES (productId + 1, price_value4).
But how do I find out the maximum value of productId?
I tried INSERT INTO mytable VALUES (SELECT MAX(productId) + 1 FROM mytable, price_value4) but it didn't work.
This should Work:
Select the max(productID) and price_value4 as a columns from mytable and insert the result.
INSERT INTO mytable (SELECT MAX(productId) + 1, 'price_value4' FROM mytable);
However, if you are not going to jump some number you can just add an auto increment id key to product_id and then you will have only to insert the price, the product ID will be incremented automatically..
This will do so :
ALTER TABLE mytable
MODIFY COLUMN `productId` INT(10) UNSIGNED PRIMARY KEY AUTO_INCREMENT;
you can change INT(10) with the INT(5) for example depanding on the size you want to give to your productId column
EDIT :
In return to the OP question in comments why his solution wouldn't work
Some suggetions says you have to make the SELECT statment in insert always between parenthesis
INSERT INTO mytable VALUES ( (SELECT MAX(ID)+1 FROM mytable) , price_value4)
.. In my Case it Return
(1093): You can't specify target table
'mytable' for update in FROM clause
AND HERE IS WHY (Quoting From the documentation)
When selecting from and inserting into the same table, MySQL creates
an internal temporary table to hold the rows from the SELECT and then
inserts those rows into the target table. However, you cannot use
INSERT INTO t ... SELECT ... FROM t when t is a TEMPORARY table,
because TEMPORARY tables cannot be referred to twice in the same
statement
BUT there is away to overcome by using a query instead of the table itself in the FROM, which has the effect of copying the requested table values instead of referencing the one that you are updating..
INSERT INTO mytable VALUES (
(SELECT MAX(ID)+1 FROM (SELECT * FROM mytable ) as mytmp ),
'price_value4');
OR (Quoting From the documentation)
To avoid ambiguous column reference problems when the SELECT and the
INSERT refer to the same table, provide a unique alias for each table
used in the SELECT part, and qualify column names in that part with
the appropriate alias.
INSERT INTO mytable Values ( (SELECT MAX(ID)+1 FROM mytable as mytmp) , 'price_value4')
This is a duplicate question. In order to take advantage of the auto-incrementing capability of the column, do not supply a value for that column when inserting rows.
A simple syntax to create table
CREATE TABLE Product (
productId MEDIUMINT NOT NULL AUTO_INCREMENT,
price INT NOT NULL,
PRIMARY KEY (productid)
);
While inserting supplied default or leave column as blank or supplied value as NULL. Take a look at below code snippet.
INSERT INTO Product (price) VALUES
('10'),('20'),('4'),
('30');
refer this link
Table containing 1 primary key and 3 foreign keys; Order_ID 'Customer_ID','Item_ID', 'DateTime_ID'
Now, the DateTime table is updated simultaneously as the row containing the previous "1 primary and 3 foreign keys" is inserted.
$sql1="INSERT INTO datetime (DateTime_ID, OrderDate, OrderTime) VALUES (NULL, CURRENT_DATE (), CURRENT_TIME() )" ;
But I am struggling to work out an INSERT INTO query.
This is what I have so far:
$sql2="INSERT INTO myorder VALUES ('NULL', menu_item WHERE item_id='$item', customer WHERE Customer_ID='$id' '$sql1')";
'$sql1' being a guess to insert the first query simultaneously.
Your example is not really clear but you may try something like this:
DECLARE p_datetime_id INTEGER;
DECLARE p_customer_id INTEGER;
DECLARE p_item_id INTEGER;
-- Initialize customer and item
SET p_customer_id = ...;
SET p_item_id = ...;
-- Create datetime element
INSERT INTO datetime (OrderDate, OrderTime)
VALUES (CURRENT_DATE(), CURRENT_TIME());
SET p_datetime_id = IDENTITY();
-- Create order element
INSERT INTO myorder (Customer_ID, Item_ID, DateTime_ID)
VALUES (p_customer_id, p_item_id, p_datetime_id);
If I have 2 tables and Table 1 has a primary key(userID) AutoIncrement and Table 2 has a foreign Key(userID) to Table 1's (userID)
When I insert a new row into Table 1 first row will have userID = 1
Then if I insert again, userID = 2.
So how do I go about keeping Table 2's userID the same when inserting in Table 1. For instance, in Table 2, I am adding the password into another table.
My question is should I add an AUTOINCREMENT to Table 2(userID) and insert a new value into both tables when I create a user OR is there another way?
You have to manually insert data with correct id in Table2. There is no such built-in functionality in MySQL.
The algorithm is as follows:
Insert row in Table1.
Get Id of the new row.
Insert row with new id in Table2.
I think what you are looking for is this ... Assuming your ID is PK and AI
INSERT INTO yourTable (var1, var2 etc etc) VALUES ('val1', 'val2' etc etc);
SELECT LAST_INSERT_ID();
To further it ..
INSERT INTO yourTable (var1, var2 etc etc) VALUES ('val1', 'val2' etc etc);
SET #last_id = LAST_INSERT_ID();
INSERT INTO yourTable2 (id, var1, var2) VALUES (#last_id, 'blah', 'blah');
I need to create a SQL script with many step in it.
First of all, I need to insert data into a Parent Table.
How can I Get the list of primary key value
Here is an example of what I'm trying to perform.
MyParentTable
MyParentID PK
col1,
col2,
col3
--INSERT VALUE INTO THE PARENT TABLE
insert into MyParentTable(col1,col2,col3)
select SDATA1,SDATA2,SDATA3
from ExampleTables
I Would like to get the list of my newly entries.
How to do that?
IMPORTANT NOTE : Consider that MyParentTable can alreaydy contains data.
insert into dbo.MyParentTable(col1,col2,col3)
output inserted.identity_column_name
select SDATA1,SDATA2,SDATA3
from dbo.ExampleTables;
If there are foreign keys involved, you may have to use a #table variable for temporary holding.
DECLARE #t TABLE(id INT);
insert into dbo.MyParentTable(col1,col2,col3)
output inserted.identity_column_name INTO #t
select SDATA1,SDATA2,SDATA3
from dbo.ExampleTables;
SELECT id FROM #t;