I receive data from a Bluetooth sensor via an ESP32 which then sends data to raspberry pi via API to MySQL. I receive the temperature on the rpi, but as 1230 instead of 12.30. Is it possible to change it in MySQL, if yes, how?
select 1230/100 will return 12.3
Do the following if you want two decimal points:
select format(temperature/100, 2)
from table1
To use this, you may want to create a view that has this calcuated field in it. You would then use the view instead of the table in your API.
create view view1 as (select format(temperature/100, 2)
from table1);
You can see how it works in Fiddle.
Related
I've created a MySQL sproc which returns 3 separate result sets. I'm implementing the npm mysql package downstream to exec the sproc and get a result structured in json with the 3 result sets. I need the ability to filter the json result sets that are returned based on some type of indicator in each result set. For example, if I wanted to get the result set from the json response which deals specifically with Suppliers then I could use some type of js filter similar to this:
var supplierResultSet = mySqlJsonResults.filter(x => x.ResultType === 'SupplierResults');
I think SQL Server provides the ability to include a hard-coded column value in a SQL result set like this:
select
'SupplierResults',
*
from
supplier
However, this approach appears to be invalid in MySQL b/c MySQL Workbench is telling me that the sproc syntax is invalid and won't let me save the changes. Do you know if something like what I'm trying to achieve is possible in MySQL and if not then can you recommend alternative approaches that would help me achieve my ultimate goal of including some type of fixed indicator in each result set to provide a handle for downstream filtering of the json response?
If I followed you correctly, you just need to prefix * with the table name or alias:
select 'SupplierResults' hardcoded, s.* from supplier s
As far as I know, this is the SQL Standard. select * is valid only when no other expression is added in the selec clause; SQL Server is lax about this, but most other databases follow the standard.
It is also a good idea to assign a name to the column that contains the hardcoded value (I named it hardcoded in the above query).
In MySQL you can simply put the * first:
SELECT *, 'SupplierResults'
FROM supplier
Demo on dbfiddle
To be more specific, in your case, in your query you would need to do this
select
'SupplierResults',
supplier.* -- <-- this
from
supplier
Try this
create table a (f1 int);
insert into a values (1);
select 'xxx', f1, a.* from a;
Basically, if there are other fields in select, prefix '*' with table name or alias
I'm trying to use Talend Open Studio for Data Integration for a BI school project. I have a txt file with some data like this :
NoClient;Name;Region;State;City;Postcode
24;Edna Thomas;West;California;Laguna Niguel;92677
I used jobs to transform data and insert it into tables. It works nicely.
Now, I'd like to handle SQL errors. For example, if the column length specified in the DB is 10 and if the job tries to insert a 11 length data in that column, I will get an SQL error.
How can I achieve it ? Is there a specific feature in tMysqlOutput or should I simply use triggers like this to check data before inserting :
CREATE TRIGGER my_trigger
BEFORE INSERT
ON my_table
FOR EACH ROW BEGIN
IF (SELECT LENGTH(NEW.Noclient)>255) THEN
// instructions
END IF
Hope it's clear enough ! Thanks in advance, sorry for bad english :-)
Maybe you can do a check in each variable in a tmap.
Like for example :
StringHandling.LEN(var) <= 10 ? var : StringHandling.LEFT(var,10)
And you adapt in function of the size of your field.
There's a component for this: tSchemaComplianceCheck
A nice example can be found at:
http://dwetl.com/2015/03/30/data-validation-using-tschemacompliancecheck/
I am trying to do is select all rows from DB, and for each row update some column for that row. Below is my camel route.
from("direct:insert").
from("sql:select * from my_table").
split(body()).
log("${body[id]}").
end();
I use the below code to start this route...
context.createProducerTemplate().sendBody("direct:insert", null);
Problem is it happens multiple times (i.e. all the id's from my_table are printed around 18 times!!). How do i make it happen just once?
Below code worked fine for me..
from("direct:insert").
to("sql:select * from my_table").
split(body()).
log("${body[id]}").
end();
Assume there is client and a server
Client:: Android mobile
Server:: AWS server
Server has mysql database installed in it
Database name:: Person
Tables in person Database:: "sam" and "carl"
Now mobile sends a request...
How to write an SQL query so that if mobile sends request i/p as
"sam" display all the values of sam table
But if the mobile sends an i/p as carl then dipslay all the values
of carl table
[Note]
I have used statement SELECT * FROM TABLE_NAME
What i am trying to achieve is a condition response when a client request comes in
I/p means :: say i get carl as ip .... i want to perform one query else sam as input ... i want to perform another query
what query statement should i need to write ?
hope i am stating my problem correctly
Thanks
First, you have to get the IP address of the Android client in your server code. In PHP (source):
$client_ip = $_SERVER['REMOTE_ADDR']
Or, if you have multiple Apache web servers behind ELB (source):
$http_headers = apache_request_headers();
$client_ip = $http_headers["X-Forwarded-For"];
Now your PHP code can choose which query to run according to the value of $client_ip. If the address is Sam's, run select * from sam, if it is Carl's, run select * from carl. If it's an unknown IP address, then you can respond with an error message.
Anyway, I don't think IP-based identification is a good idea. If Carl or Sam reboots his Android phone, its IP address will change, and the connection will no longer work.
There are problems with your database design, too. For example, if your current Sam and Carl tables contain chat messages, then the following schema would be better:
- User table: ID, Name, IPAddress
- Message table: ID, UserID, SendingTime, Text
For these tables, the query which lists the messages of the current user would look like this:
SELECT User.Name, Message.SendingTime, Message.Text
FROM User, Message
WHERE User.ID = Message.UserID AND User.IPAddress = 'xxx.xxx.xxx.xxx'
Here 'xxx.xxx.xxx.xxx' would be the value of $client_ip.
For this u have to require one more table where you store IP address and their table name and create query like this
Select tableName from IPTable where ip= 'xxx.xxx.xxx.xxx'
and using that table name in your second query
select * from tablename
I want to put completion of task in percentage (eg. 24.5,88.4,12.9,100.0,etc), the maximum value is 100.0
I have try using decimal(3,1) but it gave me maksimum of 99.9 ,
decimal(4,1) gave me maksimum of 999.9
is there any other correct data type for my problem ?
I believe MySQL still doesn't support check constraints. However, you can use an INSERT/UPDATE trigger that verifies the new value of the column and throws an error if it's outside a range that you specify.
I don't think MySQL has a native way of doing this. You are left to do it either with your external application or using a stored procedure.