datastore

(Not recommended) Create datastore to access collection of data in a database

datastore is not recommended. Use databaseDatastore instead.

Syntax

dbds = datastore(conn,sqlquery)

Description

This datastore function creates a DatabaseDatastore object. You can use this object to read large volumes of data in a relational database.

A DatabaseDatastore is one of the available datastore types. You can create other types of datastores using the MATLAB^® function datastore. After creating any datastore, you can analyze data by writing custom functions to run MapReduce using the mapreduce function. For details, see Getting Started with MapReduce.

dbds = datastore(conn,sqlquery) creates a DatabaseDatastore object dbds using the database connection conn. This datastore contains query results from the executed SQL query sqlquery.

Examples

Create a DatabaseDatastore

Create a database connection conn using the ODBC driver. This code assumes that you are connecting to a MySQL^® database with the data source named MySQL, user name username, and password pwd. MySQL contains the table named productTable with 15 product records.

 conn = database('MySQL','username','pwd');

Create a DatabaseDatastore object dbds using the database connection conn and SQL query sqlquery. This SQL query retrieves all products from the product table productTable.

sqlquery = 'SELECT * FROM productTable';

dbds = datastore(conn,sqlquery)

dbds = 

  DatabaseDatastore with properties:

       Connection: [1×1 database.odbc.connection]
            Query: 'SELECT * FROM productTable'
    VariableNames: {1×5 cell}
         ReadSize: 10000

datastore executes the SQL query sqlquery and creates a cursor object with the resulting data. dbds contains these properties:

• connection object

• Executed SQL query

• Column names of the executed SQL query

• Number of rows to read from the SQL query results

Display the database connection property Connection.

dbds.Connection

ans = 

  connection with properties:

                  DataSource: 'MySQLdb'
                    UserName: 'username'
                     Message: ''
                        Type: 'ODBC Connection Object'
  Database Properties:

                  AutoCommit: 'on'
                    ReadOnly: 'off'
                LoginTimeout: 0
      MaxDatabaseConnections: 0

  Catalog and Schema Information:

              DefaultCatalog: 'toy_store'
                    Catalogs: {'information_schema', 'toy_store'}
                     Schemas: {}

  Database and Driver Information:

         DatabaseProductName: 'MySQL'
      DatabaseProductVersion: '5.5.46-0+deb7u1'
                  DriverName: 'myodbc5a.dll'
               DriverVersion: '05.03.0004'

The Message property is blank when the database connection is successful.

Close the DatabaseDatastore and database connection.

close(dbds)

Input Arguments

conn — Database connection

connection object

Database connection, specified as an ODBC connection object or JDBC connection object created using the database function.

sqlquery — SQL statement

character vector | string scalar

SQL statement, specified as a character vector or string scalar.

For information about the SQL query language, see the SQL Tutorial.

Example: SELECT * FROM invoice selects all columns and rows from the invoice table.

Data Types: char | string

Output Arguments

dbds — Datastore containing data in database

DatabaseDatastore object

Datastore containing data in database, returned as a DatabaseDatastore object.