create solution file

solution.pl

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+/*
+Prints the names of all existing tables, one per line (use writeln/1).
+A table name is always an atom.
+*/
+tables.
+
+:- dynamic tables/1
+/*
+Unify Tables with a list of the names of all existing tables.
+*/
+tables(Tables).
+
+:- dynamic table/2
+/*
+When this predicate is executed, the effect will be the creation of a new
+table with the specified list of column names (order matters!).
+A column name is always an atom.
+If a table with the given name already exists, the predicate must throw a
+descriptive exception (use throw/1).
+All exceptions must have a descriptive error message.
+*/
+create table(Table, Cols).
+
+:- dynamic cols/2
+/*
+Unifies Cols with the list of columns for the specified table (in the same
+order as they were supplied to create table/2).
+If the given table does not exist, the predicate must throw a descriptive
+exception (use throw/1).
+*/
+cols(Table, Cols).
+
+:- dynamic row/2
+/*
+Unifies Row, one result at a time, with each row in the given Table.
+If the given table does not exist, the predicate should fail.
+*/
+row(Table, Row).
+
+:- dynamic rows/1
+/*
+Displays all rows in the given table, one per line (use writeln/1).
+If the given table does not exist, the predicate must throw a descriptive
+exception.
+*/
+rows(Table).
+
+:- dynamic insert/2
+/*
+When this predicate is executed, the effect will be the addition of a given
+row in the given table. The given row is a list of values for each of the
+corresponding columns in the table (in the order in which the columns
+were supplied to create table/2).
+If the given table does not exist, the predicate must throw a descriptive
+exception.
+If the row does not have as many elements as the number of columns in
+the table, the predicate must throw a descriptive exception.
+*/
+insert(Table, Row).
+
+:- dynamic drop/1
+/*
+When this predicate is executed, the effect will be the deletion of the given
+table.
+Do make sure that all of its rows are deleted as well, so that they don’t
+magically reappear again if you would recreate a table with the same name
+and signature later on.
+If the given table does not exist, the predicate must throw a descriptive
+exception.
+*/
+drop(Table).
+
+:- dynamic delete/1
+/*
+When this predicate is executed, the effect will be the deletion of all rows
+in the given table. The table itself should still exist after, but with no
+more rows.
+If the given table does not exist, the predicate must throw a descriptive
+exception.
+*/
+delete(Table).
+
+:- dynamic delete/2
+/*
+When this predicate is executed, the effect will be the deletion of all rows
+from the given table that match all of the given conditions. The table
+must still exist after.
+If the given table does not exist, the predicate must throw a descriptive
+exception.
+A condition is any Prolog predicate that could have been typed at the
+prompt, but which may include selectors. Selectors are terms of the form
++<column>where <column>should be replaced by a column name.
+(See tests.pl for some concrete usage examples.)
+*/
+delete(Table, Conds).
+
+:- dynamic selec/4
+/*
+Note that the name of this predicate is selec (without t) for the simple
+reason that select/4 is already a built-in Prolog predicate.
+Table is the name of a single table.
+Selectors is either * or a list of selectors. These define the resulting
+projection. * means: select all column names from the table. Other
+selectors explicitly specify which columns to pick. (See above for what
+selectors look like.) For example, +name would select the column named
+name.
+Conds has the same form as in delete/2 and works the same way: only
+rows that match all conditions are selected.
+Finally, Projection unifies with <selectors>/<projection>, where:
+•<selectors>is the list of requested selectors.
+•<projection>is a list of values coming from a single row from the
+given table that matches the conditions. This mean this predicate
+should be able to backtrack to generate all projections that match
+the query.
+For example, selec(persons,[+id,+first],[],P) returns as first result
+P = [+id, +first]/[0, "Jeffrey"].
+To obtain all projections that match the query, one could use the Prolog
+query findall(X, selec(Table, Selectors, Conds, X), Projections).
+For example: findall(X, selec(persons,[+last],[],X), Projections)
+returns Projections = [[+last]/["Bowman"],[+last]/["Michaels"],. . . ]
+Or if you only want the rows (since the selectors are repeated):
+findall(X, selec(Table, Selectors, Conds, /X), Projections).
+For example:
+findall(Values, selec(persons,[+id,+first],[],Values), Projections)
+returns: Projections = [[0, "Jeffrey"], [1, "Lorena"], [2, "Joseph"], ...
+*/
+selec(Table, Selectors, Conds, Projection)
+
+:- dynamic selec/3
+/*
+Simplified variant of the selec/4 predicate when there are no conditions
+to be checked.
+*/
+selec(TableOrTables, Selectors, Projection)
+
+:- dynamic query/2
+/*
+where Query is a string whose syntax is defined by the following grammar:
+⟨query⟩ ::= ⟨select⟩ | ⟨insert ⟩
+⟨select⟩ ::= SELECT ⟨selectors⟩ FROM ⟨table⟩ [⟨where⟩];
+⟨selectors⟩ ::= * | ⟨cols⟩
+⟨cols⟩ ::= ⟨col ⟩ [, ⟨cols⟩]
+⟨where⟩ ::= WHERE ⟨cond ⟩
+⟨insert⟩ ::= INSERT INTO ⟨table⟩ [(⟨cols⟩)] VALUES (⟨values⟩);
+⟨values⟩ ::= ⟨value⟩ [, ⟨values⟩]
+About the notation: the pipe (|) and square brackets ([]) symbols in the
+production rules above denote choice and optionality, respectively.
+<table>and <col>denote table and column names (respectively). Ta-
+ble names are atoms, while column names should follow the format out-
+lined before (+<atom>). <cond>denotes a Prolog goal, in Prolog syntax
+— following the same format as the possible values of items of the Conds
+list passed to selec and delete.
+<value>denotes a prolog value that can be stored into a row. You do
+not need to handle parsing Prolog (<cond>and <value>) by yourself,
+we’ll show how to do it below.
+The semantics of this predicate is that of the SQL-predicate contained in
+the Query string.
+A “SELECT” query maps to the selec predicate, while an “INSERT”
+query maps to the insert predicate. For “SELECT”, all instances of
+<cond>(appearing in <where>) are mapped to the Conds parameter.
+<selectors>map to the Selectors parameter. Tables names (or *) are
+mapped to the Table parameter.
+For “INSERT”, if the <cols>part is absent, the mapping to insert/2
+is straightforward. If <cols>is present, you will have to:
+    1. reorder the values according to the columns that are present;
+    2. fill in the missing columns (if any) with a null default values.
+
+Example:
+query("INSERT INTO cities (+name, +state)
+VALUES (\"Tempa\", \"Florida\");").
+maps to (for instance):
+insert(cities, ["Tempa", "Florida"]).
+When used with “SELECT”:
+•query/1 must display the results a bit like the rows predicate would.
+You have some flexibility here (displaying the selected column names
+is a nice touch for instance).
+•query/2 must pass the Result parameter as last parameter to the
+selec/4 predicate.
+For “INSERT”, nothing needs to be printed by query/1 or in case of
+success, and if query/2 is used the Result parameter can be ignored.
+*/
+query(Query, Result)
+
+:- dynamic query/1
+/*
+cf. query/2
+*/
+query(Query)