query data filtered by dynamic dates?

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Vanessa 2018-6-28

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/407856-query-data-filtered-by-dynamic-dates

Hello everyone,

I have created a query to select certain columns from a database table and among them is a date column (format yyyy-mm-dd HH:MM:SS). I want to query only the data of the last two days. How can I achieve this?

My query is like below in the where clause but it doesn't work. I'm sure that the error stays at the quotes.

%Set preferences with setdbprefs.
setdbprefs('DataReturnFormat', 'dataset');
setdbprefs('NullNumberRead', 'NaN');
setdbprefs('NullStringRead', 'null');
%Make connection to database.  Note that the password has been omitted.
%Using ODBC driver.
conn = database('', '', '');
%Read data from database.
curs = exec(conn, ['SELECT   "Flat"."SPEED_LOG"'...
    ' ,  "Flat"."ME_OUTPUT"'...
    ' ,  "Flat"."ME_REVOLUTION"'...
    ' ,  "Flat"."ME_FUEL_OIL_CONSUMPTION"'...
    ' ,  "Flat"."TIMESTAMP_UTC"'...
    ' ,  "Flat"."VESSEL_UNIQUEID"'...
    ' , "Flat"."GPS_LAT"'...
    ' ,  "Flat"."GPS_LON"'...
    ' ,  "Flat"."ME_FO_FLOW"'...
    ' ,  "Flat"."GE_FO_FLOW"'...
    ' ,  "Flat"."COMP_BLR_FUEL_OIL_FLOW"'...
    ' ,  "Flat"."AUX_BLR_FUEL_OIL_FLOW"'...
    ' ,  "Flat"."ME_FUEL_INDEX"'...
    ' ,  "Flat"."ME_SCAV_AIR_PRESS"'...
    ' ,  "Flat"."ME_LO_TOTALIZER"'...
    ' , "Flat"."DG_1_ELECTRIC_POWER"'...
    ' ,  "Flat"."DG_2_ELECTRIC_POWER"'...
    ' ,  "Flat"."DG_3_ELECTRIC_POWER"'...
    ' FROM   "setel_data"."public"."Flat" '...
    ' WHERE   "Flat"."TIMESTAMP_UTC" >= ''datetime('now','Format','yyyy-MM-dd')-2'' AND ("VESSEL_UNIQUEID"=''2537'' OR "VESSEL_UNIQUEID"=''5537'')']);
curs = fetch(curs);
close(curs);
%Assign data to output variable
Setel = curs.Data;
%Close database connection.
close(conn);
%Clear variables
clear curs conn