-#define SQL_STEP(ssh) (sql_step_wrap((ssh), #ssh, __FILE__, __LINE__))
-int sql_step_wrap(sqlite3_stmt *ssh, const char *ssh_string,
- const char *file, int line);
+#define SQL_STEP(ssh) (sql_step((ssh), #ssh, __FILE__, __LINE__))
+int sql_step(sqlite3_stmt *ssh, const char *ssh_string,
+ const char *file, int line);
+
+#define SQL_DISTINCT_DECL(cols, nintcols) \
+ int cols[nintcols]; \
+ cols[0]= -1;
+#define SQL_DISTINCT_STEP(ssh, cols, nkeycols) \
+ (sql_step_distinct((ssh), #ssh, __FILE__, __LINE__, \
+ (cols), sizeof((cols))/sizeof((cols)[0]), nkeycols))
+int sql_step_distinct(sqlite3_stmt *ssh, const char *ssh_string,
+ const char *file, int line,
+ int *cols, int ncols, int nkeycols);
+ /* These work if we're making a query whose columns consist of:
+ * - keys: integer column(s) on which the results are sorted by the query
+ * - consequences: zero or more integer cols strictly dependent on the keys
+ * - extra: zero or more further (possibly non-integer) columns
+ *
+ * Call SQL_DISTINCT_DECL, passing intcols = the total number of keys and
+ * consequences; it will declare int cols[intfields];
+ *
+ * Then each SQL_DISTINCT_STEP is like SQL_STEP only you have to
+ * pass the number of key columns and it only returns rows with
+ * distinct keys. Rows with all-identical keys are asserted to
+ * have identical consequences. After each call to
+ * SQL_DISTINCT_STEP the keys and consequences will be stored in
+ * cols.
+ */