www.gusucode.com > database 案例源码程序 matlab代码 > database/ImportDataUsingDatabaseDatastoreExample.m
%% Import Data Using a |DatabaseDatastore| Object % This example shows how to import data into MATLAB(R) using a % |DatabaseDatastore| object. To access collections of data stored in a % relational database, you can use a |<docid:database_ug.bufomil % DatabaseDatastore>| object. After creating a |DatabaseDatastore| object, % you can preview data, read data in chunks, and read every record in the % data set. % % To analyze large data, you can run algorithms on large data sets using a % tall array. For an example of using a |DatabaseDatastore| object with % tall arrays, see <docid:database_examples.example-ex44807149>. % Alternatively, you can write a MapReduce algorithm that defines the % chunking and reduction of the data. For an example, see % <docid:database_examples.example-ex81756746>. For more MapReduce % examples, see <docid:import_export.buhnu4_>. %% Create |DatabaseDatastore| Object % Using a JDBC driver, create a database connection |conn| to a % Microsoft(R) SQL Server(R) database with Windows(R) authentication. % Specify a blank user name and password. The code assumes that you % are connecting to a database |toy_store|, a database server |dbtb04|, and % port number |54317|. conn = database('toy_store','','','Vendor','Microsoft SQL Server',... 'Server','dbtb04','PortNumber',54317,'AuthType','Windows'); %% % Create a |DatabaseDatastore| object |dbds| using the database connection % |conn| and SQL query |sqlquery|. This SQL query retrieves all data from % the table |airlinesmall|. sqlquery = 'select * from airlinesmall'; dbds = databaseDatastore(conn,sqlquery); %% Preview Data in |DatabaseDatastore| Object % Preview the first eight records in the data set returned by executing % |sqlquery|. preview(dbds) %% Read Data in |DatabaseDatastore| Object % Read the first 10 records. dbds.ReadSize = 10; read(dbds) %% % Read the |DatabaseDatastore| object two more times by using the counter % |n|. Read 10 records at a time. n = 0; while(hasdata(dbds) && n~=2) read(dbds) n = n+1; end %% Reset |DatabaseDatastore| Object % Reset the |DatabaseDatastore| object to the state where no data has been % read from it. Resetting allows re-reading from the same % |DatabaseDatastore| object. reset(dbds) %% Read Every Record in |DatabaseDatastore| Object % Read every record in the |DatabaseDatastore| object in increments of % 50,000 records at a time. dbds.ReadSize = 50000; data = readall(dbds); %% % Display the first three records of the full data set. data(1:3,:) %% Close |DatabaseDatastore| Object and Database Connection close(dbds)