hasdata
Determine if data in DatabaseDatastore is
available to read
Syntax
Description
Examples
Determine If DatabaseDatastore Object Contains Data
Create a database connection using a JDBC driver. To create this connection, you must configure a JDBC data source. For more information, see the configureJDBCDataSourceDatabaseDatastore object and read the data stored in the object until no more data remains.
Create a database connection to the JDBC data source MSSQLServerJDBCAuth. This data source configures a JDBC driver to a Microsoft® SQL Server® database with Windows® authentication. Specify a blank user name and password.
datasource = "MSSQLServerJDBCAuth"; username = ""; password = ""; conn = database(datasource,username,password);
Create a DatabaseDatastore object using the database connection and an SQL query. This SQL query reads the first 30 rows of data from the airlinesmall table.
sqlquery = 'select top 30 * from airlinesmall';
dbds = databaseDatastore(conn,sqlquery);
Read the first 10 rows.
dbds.ReadSize = 10; read(dbds)
ans =
10×29 table
Year Month DayofMonth DayOfWeek DepTime CRSDepTime ArrTime CRSArrTime UniqueCarrier FlightNum TailNum ActualElapsedTime CRSElapsedTime AirTime ArrDelay DepDelay Origin Dest Distance TaxiIn TaxiOut Cancelled CancellationCode Diverted CarrierDelay WeatherDelay NASDelay SecurityDelay LateAircraftDelay
____ _____ __________ _________ _______ __________ _______ __________ _____________ _________ _______ _________________ ______________ _______ ________ ________ ______ _____ ________ ______ _______ _________ ________________ ________ ____________ ____________ ________ _____________ _________________
1987 10 30 5 1329 1329 1434 1436 'US' 683 'NA' 65 67 'NA' -2 0 'LGA' 'BUF' 292 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
1987 11 7 6 1316 1315 1713 1647 'TW' 810 'NA' 177 152 'NA' 26 1 'STL' 'BOS' 1046 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
1987 11 28 6 815 815 1015 1015 'WN' 441 'NA' 120 120 'NA' 0 0 'BNA' 'HOU' 670 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
1987 11 2 1 700 700 800 800 'NW' 790 'NA' 60 60 'NA' 0 0 'BTR' 'MEM' 319 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
1987 11 14 6 840 840 1127 1120 'CO' 733 'NA' 167 160 'NA' 7 0 'EWR' 'MCO' 938 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
1987 11 1 7 1625 1625 1823 1758 'DL' 957 'NA' 118 93 'NA' 25 0 'EWR' 'CVG' 569 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
1987 11 26 4 1314 1315 1538 1542 'AA' 398 'NA' 84 87 'NA' -4 -1 'BNA' 'RDU' 443 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
1990 10 12 5 1755 1733 1858 1820 'DL' 590 'NA' 63 47 'NA' 38 22 'BOS' 'BGR' 201 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
1990 10 19 5 1130 1120 1203 1154 'UA' 369 'NA' 93 94 'NA' 9 10 'BUF' 'ORD' 473 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
1990 10 8 1 1515 1440 1609 1535 'NW' 749 'NA' 54 55 'NA' 34 35 'MSP' 'FSD' 197 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
Determine if the DatabaseDatastore object has additional data.
hasdata(dbds)
ans = logical 1
When more data is available in dbds, hasdata returns 1.
Read the rest of the data in dbds, 10 rows at a time.
while(hasdata(dbds)) read(dbds) end
ans =
10×29 table
Year Month DayofMonth DayOfWeek DepTime CRSDepTime ArrTime CRSArrTime UniqueCarrier FlightNum TailNum ActualElapsedTime CRSElapsedTime AirTime ArrDelay DepDelay Origin Dest Distance TaxiIn TaxiOut Cancelled CancellationCode Diverted CarrierDelay WeatherDelay NASDelay SecurityDelay LateAircraftDelay
____ _____ __________ _________ _______ __________ _______ __________ _____________ _________ ________ _________________ ______________ _______ ________ ________ ______ _____ ________ ______ _______ _________ ________________ ________ ____________ ____________ ________ _____________ _________________
1990 10 23 2 1057 1055 1205 1155 'US' 1621 'NA' 68 60 'NA' 10 2 'ROC' 'EWR' 246 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
1990 10 27 6 1353 1355 1634 1640 'US' 112 'NA' 161 165 'NA' -6 -2 'TPA' 'SYR' 1104 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
1990 9 11 2 1810 1812 1939 1930 'AA' 1426 'NA' 89 78 'NA' 9 -2 'RST' 'ORD' 268 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
1992 7 18 6 1538 1540 1703 1720 'NW' 199 'NA' 145 160 'NA' -17 -2 'DCA' 'MSP' 931 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
1992 7 19 7 932 932 1130 1052 'AA' 1433 'NA' 118 80 'NA' 38 0 'DFW' 'HRL' 461 'NA' 'NA' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
1992 8 4 2 NaN 1815 NaN 1940 'US' 127 'NA' NaN 85 'NA' NaN NaN 'EWR' 'PIT' 319 'NA' 'NA' 1 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
2001 12 9 7 656 650 824 823 'DL' 1224 'N37438' 88 93 '73' 1 6 'ATL' 'BWI' 576 '4' '11' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
2001 12 22 6 1707 1715 1823 1821 'UA' 725 'N361ä1' 136 126 '104' 2 -8 'RIC' 'ORD' 642 '20' '12' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
2001 12 8 6 1402 1410 1642 1626 'NW' 809 'N324N2' 220 196 '199' 16 -8 'BOS' 'MEM' 1139 '4' '17' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
2001 12 23 7 1327 1310 1530 1530 'WN' 658 'N789@@' 63 80 '48' 0 17 'SNA' 'PHX' 338 '5' '10' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
ans =
10×29 table
Year Month DayofMonth DayOfWeek DepTime CRSDepTime ArrTime CRSArrTime UniqueCarrier FlightNum TailNum ActualElapsedTime CRSElapsedTime AirTime ArrDelay DepDelay Origin Dest Distance TaxiIn TaxiOut Cancelled CancellationCode Diverted CarrierDelay WeatherDelay NASDelay SecurityDelay LateAircraftDelay
____ _____ __________ _________ _______ __________ _______ __________ _____________ _________ ________ _________________ ______________ _______ ________ ________ ______ _____ ________ ______ _______ _________ ________________ ________ ____________ ____________ ________ _____________ _________________
2001 11 18 7 1407 1415 1442 1457 'DL' 628 'N521D1' 35 42 '22' -15 -8 'OKC' 'TUL' 111 '3' '10' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
2001 11 26 1 2105 2110 2209 2237 'AA' 1947 'N3BäA1' 64 87 '47' -28 -5 'SFO' 'LAX' 337 '6' '11' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
2001 11 22 4 1345 1355 1530 1549 'MQ' 4982 '#NAME?' 105 114 '90' -19 -10 'JAX' 'MIA' 334 '8' '7' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
2002 7 25 4 1032 1035 1853 1852 'US' 180 'N174UW' 321 317 '289' 1 -3 'SEA' 'PHL' 2378 '9' '23' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
2002 6 5 3 2032 2031 2233 2248 'AA' 3163 'N4WFAA' 241 257 '220' -15 1 'STL' 'SMF' 1679 '8' '13' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
2002 6 26 3 2026 1840 47 2257 'AA' 636 'N420AA' 141 137 '115' 110 106 'PHX' 'DFW' 868 '6' '20' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
2002 6 8 6 1557 1600 1703 1711 'HP' 660 'N334AW' 66 71 '52' -8 -3 'PHX' 'SNA' 338 '4' '10' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
2002 6 15 6 1120 1115 1401 1413 'DL' 406 'N1402A' 161 178 '132' -12 5 'FLL' 'LGA' 1076 '7' '22' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
2002 6 10 1 927 930 1031 1031 'UA' 501 'N304UA' 124 121 '101' 0 -3 'DFW' 'DEN' 641 '5' '18' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
2002 6 19 3 632 640 748 756 'NW' 126 'N773NC' 76 76 '58' -8 -8 'BIS' 'MSP' 386 '9' '9' 0 'NA' 0 'NA' 'NA' 'NA' 'NA' 'NA'
When no more data remains in dbds, hasdata returns logical 0 and the while loop stops.
Close the DatabaseDatastore object and the database connection.
close(dbds)
Input Arguments
dbds — Datastore containing data in database
DatabaseDatastore object
Datastore containing data in a database, specified as a DatabaseDatastore object
created using the databaseDatastore function.
Version History
Introduced in R2014b
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