To query the CDBS database, enter the database table name, the columns you wish to appear in the output, and a boolean expression used to select the output. Column names are separated by commas. The variables in the expression are column names in the database table. A row is retrieved from the database whenever the expression is true.
The radio buttons control the appearance of the output. You can choose to delete duplicate output rows, include the column names as titles, display the output in upper or lower case, or display the output as ascii text or HTML.
For further information about the input to this task, see below.
Operators in the expression can take one of two forms, a Fortran or SQL form. The two forms can be used interchangably. The possible operators are:
| equal | .eq. | = | not equal | .ne. | != | ||
| less than | .lt. | < | greater than | .gt. | > | ||
| less than or equal | .le. | <= | greater than or equal | .ge. | >= | ||
| and | .and. | and | or | .or. | or | ||
| negation | .not. | not | wildcard match | like |
The wildcard match operator, 'like', has no corresponding Fortran form. It allows you to do pattern matching using the wildcard characters '*' and '?'. The '*' character matches any number of characters and the '?' character matches a single character. The like operator is asymmetric, the argument on the left must be the column name and the argument on the right must be a quoted string containing wildcard characters. Please note that you cannot use wildcard characters with the equality operator, .eq., they will be interpreted as ordinary characters.
The database table columns list can also contain the wildcard characters '*' and '?'. If the first character in the list is '~', the list is negated and all columns are listed in the output except those named in the list. If the column name list is left blank, all columns will be retrieved.
More than one data base table can be queried simultaneously by passing more than one name in the list of table names. When more than one data base table is being queried, all combinations of rows in the tables are tested and those combinations for which the qualifier is true will be returned. Column names in the expression must be preceded by the table alias followed by a period. The table alias is a single character whose value depends on the position of the table name in 'params'. For example, the second database table would have the alias 'b'. If the expression mentioned the column 'version' from the second table, it would be referred to as 'b.version'. Column names referred to in the list of names may optionally be preceded by the table alias followed by a period. If a column name is not preceded by a table alias, then that column will be retrieved from all tables in which it is present, or excluded if the negation character precedes the list of column names.