DBMATCH

       Find the entry number in a database for each element of item values

       DBMATCH() is especially useful for finding a one-to-one
       correspondence between entries in different databases, and thus to
       create the vector needed for database pointers.

       list = DBMATCH( item, values, [ listin, /FULLSTRING ] )

       ITEM - Item name or number, scalar
       VALUES -  scalar or vector containing item values to search for.

       LISTIN - list of entries to be searched.  If not supplied, or
               set to -1, then all entries are searched

       LIST - vector of entry numbers with the same number of elements as
               VALUES.  Contains a value of 0 wherever the corresponding item
               value was not found.

       /FULLSTRING - By default, one has a match if a search string is
               included in any part of a database value (substring match).
               But if /FULLSTRING is set, then all characters in the database
               value must match the search string (excluding leading and
               trailing blanks).    Both types of string searches are case
               insensitive.

       DBMATCH is meant to be used for items which do not have duplicate values
       in a database (e.g. catalog numbers).  If more than one entry is found
       for a particular item value, then only the first one is stored in LIST.
       When linked databases are opened together, DBMATCH can only be
       used to search on items in the primary database.

       Make a vector which points from entries in the Yale Bright Star catalog
       to those in the Hipparcos catalog, using the HD number
       IDL> dbopen, 'yale_bs'            ;Open the Yale Bright star catalog
       IDL> dbext, -1, 'HD', hd          ;Get the HD numbers
       IDL> dbopen, 'hipparcos'          ;Open the Hipparcos catalog
       IDL> list = dbmatch( 'HD', HD)    ;Get entries in Hipparcos catalog
                                         ;corresponding to each HD number.

       DB_ITEM, DB_ITEM_INFO(), DBEXT, DBFIND_SORT()

       Written,    W. Landsman      STX     February, 1990
       Fixed error when list in parameter used May, 1992
       Faster algorithm with sorted item when listin parameter supplied
       Added keyword FULLSTRING,check for empty database, William Thompson,
               GSFC, 15 March 1995
       Work for more than 32767 values, added CATCH W. Landsman   July 1997
       Converted to IDL V5.0   W. Landsman 25-Nov-1997
       Change some loop variables to type LONG,  W. Landsman  July 1999
       Remove loop for substring searches (faster)  W. landsman August 1999
       Replace DATATYPE() with size(/TNAME)  W. Landsman  November 2001
       Fixed typo when search on sorted items W. Landsman February 2002

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