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 Compatibility Considerations.
Syntax
Description
Examples
Determine If Database Cursor Is Open
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 = 1
Import 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 = 24
After 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 R2015bR2018b: isopen
function is not recommended
The 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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