isopen
(Not recommended) Determine if database cursor is open
The isopen function is not recommended. There is no replacement for
this functionality. To import data, use the fetch function. For details, see Version History.
Syntax
Description
Examples
Connect to a Microsoft® SQL Server® database and verify the database cursor. Then, import data from the database into MATLAB®. Determine the highest unit cost among the retrieved products in the table. Close the database cursor and database connection.
Create an ODBC database connection to a Microsoft
SQL Server database with Windows® authentication. Specify a blank user name and password. The database
contains the table productTable.
datasource = 'MS SQL Server Auth'; conn = database(datasource,'','');
Check the database connection. If the Message property is empty,
the connection is successful.
conn.Message
ans =
[]
Create a cursor object by executing an SQL query in the database.
Select all the data from the table productTable by using the
connection object, and then sort the data by the product
number.
sqlquery = 'SELECT * FROM productTable ORDER BY productNumber';
curs = exec(conn,sqlquery);Determine if the database cursor is open. The isopen function
returns the numeric scalar 1, which means the database cursor is
open.
i = isopen(curs)
i =
1Import data from the executed SQL query and display the first three rows.
curs = fetch(curs); curs.Data(1:3,:)
ans =
3×5 table
productNumber stockNumber supplierNumber unitCost productDescription
_____________ ___________ ______________ ________ __________________
1 4.0035e+05 1001 14 'Building Blocks'
2 4.0031e+05 1002 9 'Painting Set'
3 4.01e+05 1009 17 'Slinky'
Determine the highest unit cost in the table.
data = curs.Data; max(data.unitCost)
ans =
24After you finish working with the cursor object, close it.
close(curs)
Determine if the database cursor is closed. The isopen function
returns the numeric scalar 0, which means the database cursor is
closed. If the cursor object is invalid, the
isopen function returns the same result.
i = isopen(curs)
i =
0
Close the database connection.
close(conn)
Input Arguments
Version History
Introduced in R2015bThe isopen function is not recommended. Use the fetch function to import data. Some differences between the workflows might
require updates to your code.
There are no plans to remove the isopen function at this
time.
Use the fetch function with the connection
object to import data from a database in one step.
In prior releases, you wrote multiple lines of code to create the cursor object, determine if the cursor object is open, and
import data. For example:
curs = exec(conn,sqlquery); i = isopen(curs); curs = fetch(curs); results = curs.Data; close(curs)
Now you can import data in one step using the fetch
function.
results = fetch(conn,sqlquery);
There is no replacement functionality for the isopen
function.
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