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How to read multiple result sets returned from a SQL Server stored procedure in R
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Closed 3 years ago.
I am using RODBC to query data from SQL SERVER.
How can I get both tables when the result contains two tables?
Currently my code is as follow
library(RODBC)
channel <- odbcDriverConnect("driver={SQL Server};server=xxxx;atabase=xx;uid=xx;pwd=xxx")
initdata<- sqlQuery(channel,paste("select * from roles;select * from seat"))
odbcClose(channel)
The initdata contains result only from table roles
In fact, my query is a stored procedure like "exec XXX" and the stored procedure returns multiple tables. I wonder if there is a way to get all the result tables.
why don't you use 2 results or dataframes?
dataframes:
initroles <- sqlFetch(channel, "roles")
initseats <- sqlFetch(channel, "seat")
resultsets:
initroles <- sqlQuery(channel, "select * from roles")
initseats <- sqlQuery(channel, "select * from seat")
My syntax might be a little off, but I would try
SELECT * FROM roles JOIN seat ON roles.id = seat.id
Where roles.id and seat.id are the ID variables that link roles and seat.
Related
I work with large databases that needs to be stored into a server.
So, to work with them on Rstudio I have to open a connection to my Microsoft SQL Server with the dbConnect function :
conn <- dbConnect(odbc(),"myconnection",uid="***",pwd="***",schema="dbo",access="readonly")
and in order to use dplyr, I have to create data references with the tbl function :
data <- tbl(conn, "data")
But one of the online dataframe contains a columns that I can't read because I dont have the access, but I can read everything else.
The SQL query behind the tbl() function is :
SELECT * FROM data
and this is my problem.
Even when I try to select a specific column it doesn't work (see below), so I can't create my references and I can't work.
select(tbl(conn, "data"), "columnX")
=
SELECT columnX FROM data
I think this is the tbl() function and the call of "SELECT *" that blocks me.
Do you know what can I do ? Is there smilar functions that could resolve my problem ?
If you know the columns that you have access to, then one option is to bypass the default access SELECT * FROM ... with your own SQL query.
A remote table is defined by two components:
The database conneciton
The query to the database
When you connect with the default approach tbl(conn, 'data') then it defaults to a query SELECT * FROM data.
But here is another approach:
custom_query = 'SELECT columnX FROM data'
remote_table = tbl(conn, dbplyr::sql(customer_query))
I've been working to parameterize a SQL Statement that uses the IN statement in the WHERE clause. I'm using rodbcext library for parameterizing but it seems to lack expansion of a list.
I was hoping to write code such as
sqlExecute("SELECT * FROM table WHERE name IN (?)", c("paul","ringo","john", "george")
I'm using the following code but wondered if there's an easier way.
library(RODBC)
library(RODBCext)
# Search inputs
names <- c("paul", "ringo", "john", "george")
# Build SQL statement
qmarks <- replicate(length(names), "?")
stringmarks <- paste(qmarks, collapse = ",")
sql <- paste("SELECT * FROM tableA WHERE name IN (", stringmarks, ")")
# expand to Columns - seems to be the magic step required
bindnames <- rbind(names)
# Execute SQL statement
dbhandle <- RODBC::odbcDriverConnect(connectionString)
result <- RODBCext::sqlExecute(dbhandle, sql, bindnames, fetch = TRUE)
RODBC::odbcClose(dbhandle)
It works but feel I'm using R to expand the strings in the wrong way (bit new to R - so many ways to do the same thing wrong). Somebody will probably say "that creates factors - never do that" :-)
I found this article which suggest I'm on the right track but it doesn't discuss having to expand the "?" and turn the list into columns of a data.frame
R RODBC putting list of numbers into an IN() statement
Thank you.
UPDATE: As Benjamin shows below - the sqlExecute function can handle a list() of inputs. However upon inspection of the resulting SQL I discovered that it uses cursors to rollup the results. This significantly increases the CPU and I/O over the sample code I show above.
While the library can indeed solve this for you, for large results it may be too expensive. There are two answers and it depends upon your needs.
Since your only parameter in the query is in collection for IN, you could get away with
sqlExecute(dbhandle,
"SELECT * FROM table WHERE name IN (?)",
list(c("paul","ringo","john", "george")),
fetch = TRUE)
sqlExecute will bind the values in the list to the question mark. Here, it will actually repeat the query four times, once for each value in the vector. It may seem kind of silly to do it this way, but when trying to pass strings, it's a lot safer in many ways to let the binding take care of setting up the appropriate quote structure rather than trying to paste it in yourself. You will generate fewer errors this way and avoid a lot of database security concerns.
What if you declare a variable table in a character object and then concatenate with the query.
library(RODBC)
library(RODBCext)
# Search inputs
names <- c("paul", "ringo", "john", "george")
# Build SQL statement
sql_top <- paste0( "SET NOCOUNT ON \r\n DECLARE #LST_NAMES TABLE (ID NVARCHAR(20)) \r\n INSERT INTO #LST_NAMES VALUES ('", paste(names, collapse = "'), ('" ) , "')")
sql_body <- paste("SELECT * FROM tableA WHERE name IN (SELECT id FROM #LST_NAMES)")
sql <- paste0(sql_top, "\r\n", sql_body)
# Execute SQL statement
dbhandle <- RODBC::odbcDriverConnect(connectionString)
result <- RODBCext::sqlExecute(dbhandle, sql, bindnames, fetch = TRUE)
RODBC::odbcClose(dbhandle)
The query will be (the set no count on is important to retrieve the results)
SET NOCOUNT ON
DECLARE #LST_NAMES TABLE (ID NVARCHAR(20))
INSERT INTO #LST_NAMES VALUES ('paul'), ('ringo'), ('john'), ('george')
SELECT * FROM tableA WHERE name IN (SELECT id FROM #LST_NAMES)
I have a page that ask of users opinion about a topic. Their responses are then saved into a table. What I want to do is to check how many users selected an option 1,2,3 and 4.
What I have now are multiple T-SQL queries that run successfully but I believe there is a simplified version of the code I have written. I would be grateful if someone can simplify my queries into one single query. Thank you.
here is sample of data in the database table
enter image description here
$sql4 = "SELECT COUNT(CO) FROM GnAppItms WHERE CO='1' AND MountID='".$mountID."'";
$stmt4 = sqlsrv_query($conn2, $sql4);
$row4 = sqlsrv_fetch_array($stmt4);
$sql5="SELECT COUNT(CO) FROM GnAppItms WHERE CO='2' AND MountID='".$mountID."'";
$stmt5=sqlsrv_query($conn2,$sql5);
$row5=sqlsrv_fetch_array($stmt5);
$sql6="SELECT COUNT(CO) FROM GnAppItms WHERE CO='3' AND MountID='".$mountID."'";
$stmt6=sqlsrv_query($conn2,$sql6);
$row6=sqlsrv_fetch_array($stmt6);
$sql7="SELECT COUNT(CO) FROM GnAppItms WHERE CO='4' AND MountID='".$mountID."'";
$stmt7=sqlsrv_query($conn2,$sql7);
$row7=sqlsrv_fetch_array($stmt7);
You can do it by using group by in sql server
example :
create table a
(id int,
mountid nvarchar(100),
co int,
)
insert into a values (1,'aa',1)
insert into a values (2,'aa',2)
insert into a values (3,'aa',1)
insert into a values (4,'aa',2)
insert into a values (5,'aa',3)
Query
select co,count(co)as countofco from a
where mountid='aa'
group by
co
result
co countofco
1 2
2 2
3 1
Note : Beware of SQL injection when you are writing a sql query, so always use parametrized query. You can edit the above example code and make it as a parametrized query for preventing sql injection
I've been tinkering with running R commands on a SQL server by calling a procedure which runs an OLS regression using the R lm() function on a few made-up data pts in the SQL database "my_schema.data", and then outputs the object as a SQL database.
My strategy is to first create an empty SQL database named "my_schema.ols_model_db" which will then be populated with the values in the ols_model object which has been transformed into a data.frame class.
I'm almost there, but can't quite figure out how to convert the ols_model object into an R data.frame, nor do I know what the column headers will be (which we need to know in advance in order to populate the empty SQL database my_schema.ols_model_db).
Which code should be inserted into "???" in the program below?
my_schema.data
y x
1 5
2 9
3 17
4 26
CREATE COLUMN TABLE "my_schema"."my_schema.ols_model_db"(???);
CREATE PROCEDURE my_schema.proc_Rcode( IN train my_schema.data, OUT ols_model_db my_schema.ols_model_db )
LANGUAGE RLANG AS BEGIN
ols_model <- lm(y ~ x, data=train)
ols_model_db <- data.frame(g=I(lapply(ols_model, function(x) {serialize(x, NULL)})))
???
END
CALL my_schema.proc_Rcode( my_schema.data my_schema.ols_model_db )
I am trying to use GO to get R to pull a multipart query from a SQL Server database but R keeps erroring out on me when I try this. Does anyone know a workaround to get RODBC to run multipart queries?
Example query:
query2 = "IF OBJECT_ID('tempdb..#ATTTempTable') IS NOT NULL
DROP TABLE #ATTTempTable
GO
SELECT
* INTO #ATTTempTable
FROM ETL.ATT.fact_responses fr
WHERE fr.ResponseDateTime > '2015-07-06'
"
channel <- odbcConnect("<host name>", uid="<uid>", pwd="<pwd>")
raw = sqlQuery(channel, query2)
close(channel)
and result
> raw
[1] "42000 102 [Microsoft][ODBC Driver 11 for SQL Server][SQL Server]Incorrect syntax near 'GO'."
[2] "[RODBC] ERROR: Could not SQLExecDirect 'IF OBJECT_ID('tempdb..#ATTTempTable') IS NOT NULL\n DROP TABLE #ATTTempTable\n\nGO\n\nSELECT\n\t* INTO #ATTTempTable\nFROM ETL.ATT.fact_responses fr\nWHERE fr.ResponseDateTime > '2015-07-06'\n'"
>
Because your query contains multiple line with conditional logic it resembles a stored procedure.
Simply save that stored procedure in SQL Server:
CREATE PROCEDURE sqlServerSp #ResponseDateTime nvarchar(10)
AS
IF OBJECT_ID('tempdb..#ATTTempTable') IS NOT NULL
DROP TABLE #ATTTempTable;
GO
-- suppresses affected rows message so RODBC returns a dataset
SET NO COUNT ON;
GO
-- runs make-table action query
SELECT * INTO #ATTTempTable
FROM ETL.ATT.fact_responses fr
WHERE fr.ResponseDateTime > #ResponseDateTime;
GO
And then run the stored procedure in R. You can even pass parameters like the date:
channel <- odbcConnect("<host name>", uid="<uid>", pwd="<pwd>")
raw = sqlQuery(channel, "EXEC sqlServerSp #ResponseDateTime='2015-07-06'")
close(channel)
You can't. See https://msdn.microsoft.com/en-us/library/ms188037.aspx
you have to divide your query into two statements and run them separately.