diff --git a/Makefile b/Makefile
index e69d3f0..f0f3ca0 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@
 .include "config.mk"
 
 CC=clang
-CFLAGS=-std=c11 -Wall ${SQLITE3_CFLAGS}
+CFLAGS=-g -std=c11 -Wall ${SQLITE3_CFLAGS}
 LD=clang
 LDFLAGS=-lgpio -lfigpar -lpthread ${SQLITE3_LDFLAGS}
 SRCS=src/main.c src/util.c src/lcd.c src/ths.c src/button.c src/screen.c
diff --git a/src/main.c b/src/main.c
index 0edd289..1d47a8f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -91,14 +91,17 @@ int main(int argc, char *const *argv) {
                         GLOBAL_OPTS.data_pins[7]);
     setup_signals();
     open_database();
+    initialize_util_queries(DATABASE);
     pthread_t bg_update;
     start_update_thread(&bg_update);
-    ScreenManager *screen_manager = screen_manager_new(lcd, handle,
+    ScreenManager *screen_manager = screen_manager_new(DATABASE,
+                                                       lcd, handle,
                                                        GLOBAL_OPTS.back_pin,
                                                        GLOBAL_OPTS.up_pin,
                                                        GLOBAL_OPTS.down_pin,
                                                        GLOBAL_OPTS.sel_pin);
     screen_manager_add(screen_manager, (Screen *) stats_screen_new());
+    screen_manager_add(screen_manager, (Screen *) stats_by_screen_new());
     while (RUNNING) {
         lock_stat_globals();
         uint32_t temp = LAST_TEMP;
@@ -115,6 +118,7 @@ int main(int argc, char *const *argv) {
         err(1, "join of background thread failed");
     }
     // this needs to be done after bg_update exits
+    cleanup_util_queries();
     sqlite3_close(DATABASE);
     pthread_mutex_destroy(&STAT_MUTEX);
     gpio_close(handle);
@@ -386,12 +390,12 @@ void parse_config_file(const char *path) {
             .action = parse_uint_callback,
         },
         {
-            .directive = "down_pin",
+            .directive = "up_pin",
             .type = FIGPAR_TYPE_NONE,
             .action = parse_uint_callback,
         },
         {
-            .directive = "up_pin",
+            .directive = "down_pin",
             .type = FIGPAR_TYPE_NONE,
             .action = parse_uint_callback,
         },
@@ -430,6 +434,9 @@ void parse_config_file(const char *path) {
 static void exit_signal_callback(int sig) {
     LOG_VERBOSE("Caught signal %d. Exiting...\n", sig);
     RUNNING = false;
+    if (signal(sig, SIG_DFL) == SIG_ERR) {
+        err(1, "resetting signal handler failed");
+    }
 }
 
 #define SIGNAL_SETUP_CHECKED(sig) \
@@ -497,13 +504,13 @@ static void create_db_table() {
     LOG_VERBOSE("Ensured env_data table existance\n");
 }
 
-static const char *UPDATE_STATES_QUERY =
+static const char *UPDATE_STATS_QUERY =
     "INSERT INTO env_data (time, temp, humid) "
     "VALUES(?, ?, ?);";
 static void *update_thread_action(void *_ignored) {
     create_db_table();
     sqlite3_stmt *insert_statement = NULL;
-    int status = sqlite3_prepare_v2(DATABASE, UPDATE_STATES_QUERY, -1,
+    int status = sqlite3_prepare_v2(DATABASE, UPDATE_STATS_QUERY, -1,
                                     &insert_statement, NULL);
     if (status != SQLITE_OK) {
         errx(1, "could not compile SQL query. sqlite3 error follows:\n%s",
diff --git a/src/screen.c b/src/screen.c
index f6e4b3d..7a08c21 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -8,11 +8,12 @@
  * version. See the LICENSE file for more information.
  */
 #include "screen.h"
-#include "util.h"
 #include "ths.h"
 
 #include <err.h>
 #include <inttypes.h>
+#include <limits.h>
+#include <string.h>
 
 
 void screen_init(Screen *screen, const char *name,
@@ -30,10 +31,11 @@ void screen_delete(Screen *screen) {
     }
 }
 
-ScreenManager *screen_manager_new(LCD *lcd, gpio_handle_t handle,
+ScreenManager *screen_manager_new(sqlite3 *db, LCD *lcd, gpio_handle_t handle,
                                   gpio_pin_t back_pin, gpio_pin_t up_pin,
                                   gpio_pin_t down_pin, gpio_pin_t sel_pin) {
     ScreenManager *sm = malloc_checked(sizeof(ScreenManager));
+    sm->db = db;
     sm->lcd = lcd;
     sm->screens = NULL;
     sm->screen_count = 0;
@@ -133,7 +135,7 @@ void screen_manager_dispatch(ScreenManager *sm, uint32_t temp, uint32_t humid) {
     }
 }
 
-bool stats_screen_dispatch(StatsScreen *screen, SensorState *state) {
+static bool stats_screen_dispatch(StatsScreen *screen, SensorState *state) {
     if (state->back_down) {
         return true;
     }
@@ -168,3 +170,292 @@ StatsScreen *stats_screen_new() {
     s->last_temp = 0;
     return s;
 }
+
+static const char *PERIOD_LABELS[] = {
+    "HOUR",
+    "DAY",
+    "WEEK",
+    "MONTH",
+    "YEAR", 
+};
+static const size_t NPERIOD = sizeof(PERIOD_LABELS) / sizeof(char *);
+
+static void stats_by_select_period(StatsByScreen *screen, SensorState *state) {
+    if (state->up_down) {
+        screen->period = (screen->period + 1) % NPERIOD;
+        screen->need_redraw = true;
+    }
+    if (state->down_down) {
+        if (--screen->period < 0) {
+            screen->period = NPERIOD - 1;
+        }
+        screen->need_redraw = true;
+    }
+    if (screen->need_redraw) {
+        lcd_clear(state->lcd);
+        lcd_move_to(state->lcd, 0, 0);
+        lcd_write_string(state->lcd, "Period:");
+        lcd_move_to(state->lcd, 1, 0);
+        lcd_write_string(state->lcd, ">");
+        lcd_write_string(state->lcd, PERIOD_LABELS[screen->period]);
+        lcd_move_to(state->lcd, 1, 0);
+        lcd_display_control(state->lcd, LCD_CURSOR_BLINK, LCD_CURSOR_ON,
+                            LCD_DISPLAY_ON);
+        screen->need_redraw = false;
+    }
+    if (state->sel_down) {
+        ++screen->stage;
+        switch (screen->period) {
+        case 0:
+        case 1:
+        case 2:
+            screen->ds.max_stage = DATE_SEL_DAY;
+            break;
+        case 3:
+            screen->ds.max_stage = DATE_SEL_MONTH;
+            break;
+        case 4:
+            screen->ds.max_stage = DATE_SEL_YEAR;
+            break;
+        }
+        screen->need_redraw = true;
+    }
+}
+
+void date_sel_init(DateSelection *ds, int start_line, int start_col,
+                   DateSelectionStage max_stage) {
+    ds->max_stage = max_stage;
+    ds->start_line = start_line;
+    ds->start_col = start_col;
+    memset(&ds->start_time, 0, sizeof(UtilDate)); // min date
+    memset(&ds->end_time, 0xff, sizeof(UtilDate)); // max date
+    date_sel_reset(ds);
+}
+
+void date_sel_reset(DateSelection *ds) {
+    ds->year = -1;
+    ds->stage = DATE_SEL_YEAR;
+}
+
+static void date_sel_clamp_time(DateSelection *ds) {
+    if (ds->year > ds->end_time.local_year) {
+        ds->year = ds->end_time.local_year;
+    }
+    if (ds->year == ds->end_time.local_year &&
+        ds->month > ds->end_time.local_month) {
+        ds->month = ds->end_time.local_month;
+    }
+    if (ds->month == ds->end_time.local_year &&
+        ds->month == ds->end_time.local_month &&
+        ds->day > ds->end_time.local_day) {
+        printf("Clamp Day High!\n");
+        ds->day = ds->end_time.local_day;
+    }
+    if (ds->year < ds->start_time.local_year) {
+        ds->year = ds->start_time.local_year;
+    }
+    if (ds->year == ds->start_time.local_year &&
+        ds->month < ds->start_time.local_month) {
+        ds->month = ds->start_time.local_month;
+    }
+    if (ds->year == ds->start_time.local_year &&
+        ds->month == ds->start_time.local_month &&
+        ds->day < ds->start_time.local_day) {
+        printf("Clamp Day Low!\n");
+        ds->day = ds->start_time.local_day;
+    }
+    printf("Max: %d %d %d\n", ds->end_time.local_year, ds->end_time.local_month, ds->end_time.local_day);
+    printf("Min: %d %d %d\n", ds->start_time.local_year, ds->start_time.local_month, ds->start_time.local_day);
+    printf("Cur: %d %d %d\n", ds->year, ds->month, ds->day);
+}
+
+static void date_sel_cleanup(DateSelection *ds) {
+    if (ds->month < 1) {
+        ds->month = 12 - ds->month;
+        --ds->year;
+    } else if (ds->month > 12) {
+        ds->month = (ds->month % 13) + 1;
+        ++ds->year;
+    }
+    int ndays = days_in_month(ds->month, ds->year);
+    if (ds->day == 33) {
+        ds->day = ndays;
+    } else if (ds->day < 1) {
+        ds->day = 33; // this means last day of month
+        --ds->month;
+        date_sel_cleanup(ds);
+    } else if (ds->day > ndays) {
+        ds->day = 1;
+        ++ds->month;
+        date_sel_cleanup(ds);
+    }
+    date_sel_clamp_time(ds);
+}
+
+static void date_sel_add_units(DateSelection *ds, int n) {
+    switch (ds->stage) {
+    case DATE_SEL_YEAR:
+        ds->year += n;
+        break;
+    case DATE_SEL_MONTH:
+        ds->month += n;
+        break;
+    case DATE_SEL_DAY:
+        ds->day += n;
+        break;
+    }
+    date_sel_cleanup(ds);
+}
+
+DateSelectionState date_sel_dispatch(DateSelection *ds, SensorState *state) {
+    if (ds->year == -1) {
+        time_t utc_time = time(NULL);
+        struct tm local_time;
+        localtime_r(&utc_time, &local_time);
+        ds->year = local_time.tm_year + 1900;
+        if (ds->max_stage > DATE_SEL_YEAR) {
+            ds->month = local_time.tm_mon + 1;
+        }
+        if (ds->max_stage > DATE_SEL_MONTH) {
+            ds->day = local_time.tm_mday;
+        }
+        date_sel_cleanup(ds);
+    }
+    if (ds->max_stage < DATE_SEL_MONTH) {
+        ds->month = 1;
+    }
+    if (ds->max_stage < DATE_SEL_DAY) {
+        ds->day = 1;
+    }
+    if (state->back_down) {
+        if (ds->stage == DATE_SEL_YEAR) {
+            return DATE_SEL_BACK;
+        }
+        --ds->stage;
+    }
+    if (state->up_down || state->down_down) {
+        date_sel_add_units(ds, state->up_down - state->down_down);
+    }
+    if (state->sel_down) {
+        if (ds->stage == ds->max_stage) {
+            return DATE_SEL_DONE;
+        }
+        ++ds->stage;
+    }
+    int buf_size = 17 - ds->start_col;
+    char buff[buf_size];
+    int cursor_pos;
+    const char *format;
+    switch (ds->stage) {
+    case DATE_SEL_YEAR:
+        cursor_pos = 0;
+        format = ">%04d/%02d/%02d";
+        break;
+    case DATE_SEL_MONTH:
+        cursor_pos = 5;
+        format = "%04d/>%02d/%02d";
+        break;
+    case DATE_SEL_DAY:
+        cursor_pos = 8;
+        format = "%04d/%02d/>%02d";
+        break;
+    default:
+        LOG_VERBOSE("Date selector tried to select bad field\n");
+        return DATE_SEL_BACK;
+    }
+    snprintf(buff, buf_size, format, ds->year, ds->month, ds->day);
+    cursor_pos += ds->start_col;
+    lcd_move_to(state->lcd, ds->start_line, ds->start_col);
+    lcd_write_string(state->lcd, buff);
+    lcd_display_control(state->lcd, LCD_CURSOR_BLINK, LCD_CURSOR_ON,
+                        LCD_DISPLAY_ON);
+    lcd_move_to(state->lcd, ds->start_line, cursor_pos);
+    return DATE_SEL_CONTINUE;
+}
+
+static void stats_by_select_start(StatsByScreen *screen, SensorState *state) {
+    if (state->up_down || state->down_down || state->sel_down || state->back_down) {
+        screen->need_redraw = true;
+        UtilDate start, end;
+        if (!get_database_limits(state->db, PERIOD_LABELS[screen->period],
+                                 &start, &end)) {
+            warnx("failed to query database limits");
+            --screen->stage;
+            return;
+        }
+        screen->ds.start_time = start;
+        screen->ds.end_time = end;
+    }
+    if (screen->need_redraw) {
+        lcd_clear(state->lcd);
+        lcd_move_to(state->lcd, 0, 0);
+        lcd_write_string(state->lcd, "Start: ");
+        lcd_move_to(state->lcd, 1, 0);
+        screen->need_redraw = false;
+        DateSelectionState dss = date_sel_dispatch(&screen->ds, state);
+        switch (dss) {
+        case DATE_SEL_BACK:
+            screen->need_redraw = true;
+            lcd_display_control(state->lcd, LCD_CURSOR_NO_BLINK, LCD_CURSOR_OFF,
+                                LCD_DISPLAY_ON);
+            --screen->stage;
+            return;
+        case DATE_SEL_CONTINUE:
+            break; // ignore
+        case DATE_SEL_DONE:
+            ++screen->stage;
+            screen->need_redraw = true;
+            break;
+        }
+    } 
+}
+
+static bool stats_by_screen_dispatch(StatsByScreen *screen,
+                                     SensorState *state) {
+    if (state->force_draw) {
+        screen->need_redraw = true;
+    }
+    if (state->back_down) {
+        if (screen->stage == STATS_BY_SELECT_PERIOD) {
+            screen->need_redraw = true;
+            lcd_display_control(state->lcd, LCD_CURSOR_NO_BLINK, LCD_CURSOR_OFF,
+                                LCD_DISPLAY_ON);
+            date_sel_reset(&screen->ds);
+            return true;
+        }
+    }
+    switch (screen->stage) {
+    case STATS_BY_SELECT_PERIOD:
+        stats_by_select_period(screen, state);
+        break;
+    case STATS_BY_SELECT_START:
+        stats_by_select_start(screen, state);
+        break;
+    case STATS_BY_SHOWING:
+        if (state->back_down) {
+            screen->stage = STATS_BY_SELECT_PERIOD;
+            screen->need_redraw = true;
+            screen->ds.stage = DATE_SEL_YEAR;
+        } else if (screen->need_redraw) {
+            lcd_clear(state->lcd);
+            lcd_move_to(state->lcd, 0, 0);
+            lcd_write_string(state->lcd, "Some data!");
+            screen->need_redraw = false;
+        }
+        break;
+    default:
+        LOG_VERBOSE("Attempt to show bad stats by screen\n");
+        return true;
+    }
+    return false;
+}
+
+StatsByScreen *stats_by_screen_new() {
+    StatsByScreen *s = malloc_checked(sizeof(StatsByScreen));
+    screen_init(&s->parent, "Stats by...",
+                (ScreenDispatchFunc) stats_by_screen_dispatch,
+                (ScreenCleanupFunc) free);
+    s->need_redraw = true;
+    date_sel_init(&s->ds, 1, 0, DATE_SEL_DAY);
+    return s;
+}
diff --git a/src/screen.h b/src/screen.h
index adb934d..81bac00 100644
--- a/src/screen.h
+++ b/src/screen.h
@@ -12,11 +12,14 @@
 
 #include "button.h"
 #include "lcd.h"
+#include "util.h"
 
 #include <time.h>
 #include <libgpio.h>
+#include <sqlite3.h>
 
 typedef struct {
+    sqlite3 *db;
     LCD *lcd;
     uint32_t temp;
     uint32_t humid;
@@ -52,6 +55,7 @@ void screen_init(Screen *screen, const char *name,
 void screen_delete(Screen *screen);
 
 typedef struct {
+    sqlite3 *db;
     LCD *lcd;
     Button *back_btn;
     Button *up_btn;
@@ -68,10 +72,11 @@ typedef struct {
 } ScreenManager;
 
 /*
- * Crate a new ScreenManager with the given LCD and buttons
+ * Crate a new ScreenManager with the given DB, LCD and buttons. DB and LCD
+ * still owned by the caller!
  * Return: the new ScreenManager
  */
-ScreenManager *screen_manager_new(LCD *lcd, gpio_handle_t handle,
+ScreenManager *screen_manager_new(sqlite3 *db, LCD *lcd, gpio_handle_t handle,
                                   gpio_pin_t back_pin, gpio_pin_t up_pin,
                                   gpio_pin_t down_pin, gpio_pin_t sel_pin);
 
@@ -99,6 +104,71 @@ typedef struct {
     time_t last_min;
 } StatsScreen;
 
+/*
+ * Create a new stats screen. This screen will display the current temp. and
+ * humidity data from a THS sensor.
+ */
 StatsScreen *stats_screen_new(void);
 
+typedef enum {
+    DATE_SEL_YEAR,
+    DATE_SEL_MONTH,
+    DATE_SEL_DAY,
+} DateSelectionStage;
+
+typedef struct {
+    int year;
+    int month;
+    int day;
+    DateSelectionStage stage;
+    DateSelectionStage max_stage;
+    int start_line;
+    int start_col;
+    UtilDate start_time;
+    UtilDate end_time;
+} DateSelection;
+
+typedef enum {
+    DATE_SEL_BACK,
+    DATE_SEL_CONTINUE,
+    DATE_SEL_DONE
+} DateSelectionState;
+
+/*
+ * Initialize a DateSelection. START_LINE and START_COL are the first line and
+ * column where it should draw the widget. MAX_STAGE is the most specific field
+ * to select.
+ */
+void date_sel_init(DateSelection *ds, int start_line, int start_col,
+                   DateSelectionStage max_stage);
+
+/*
+ * Reset the date on DS.
+ */
+void date_sel_reset(DateSelection *ds);
+
+/*
+ * Dispatch a DateSelection by processing STATE to continue the selection.
+ * Return: weather the user backed out, is still working, or is done
+ */
+DateSelectionState date_sel_dispatch(DateSelection *ds, SensorState *state);
+
+typedef struct {
+    Screen parent;
+    enum {
+        STATS_BY_SELECT_PERIOD = 0,
+        STATS_BY_SELECT_START,
+        STATS_BY_SHOWING,
+    } stage;
+    bool need_redraw;
+    int period;
+    DateSelection ds;
+} StatsByScreen;
+
+/*
+ * Create a new stats by screen. This screen will display data from the database
+ * by hour, day, week, month, and year.
+ */
+StatsByScreen *stats_by_screen_new(void);
+
 #endif
diff --git a/src/util.c b/src/util.c
index f291604..cc0ff18 100644
--- a/src/util.c
+++ b/src/util.c
@@ -45,3 +45,103 @@ void *strdup_checked(const char *str) {
     }
     return new_str;
 }
+
+int days_in_month(int m, int y) {
+    switch (m) {
+    case 2:
+        if (y % 4 == 0 && (y % 100 != 0 || y % 400 == 0)) {
+            return 29;
+        } else {
+            return 28;
+        }
+        break;
+    case 1:
+    case 3:
+    case 5:
+    case 7:
+    case 8:
+    case 10:
+    case 12:
+        return 31;
+    default:
+        return 30;
+    }
+}
+
+// is this even a C program anymore?
+static const char *DB_LIMITS_QUERY_STR =
+    "SELECT\n"
+    "MinUTC,\n"
+    // labels below are for debugging
+    "strftime('%Y', MinUTC, 'unixepoch') as MinUTCYear,\n"
+    "strftime('%m', MinUTC, 'unixepoch') as MinUTCMonth,\n"
+    "strftime('%e', MinUTC, 'unixepoch') as MinUTCDay,\n"
+    "MinLocal,\n"
+    "strftime('%Y', MinLocal, 'unixepoch') as MinLocalYear,\n"
+    "strftime('%m', MinLocal, 'unixepoch') as MinLocalMonth,\n"
+    "strftime('%e', MinLocal, 'unixepoch') as MinLocalDay,\n"
+    "MaxUTC,\n"
+    "strftime('%Y', MaxUTC, 'unixepoch') as MaxUTCYear,\n"
+    "strftime('%m', MaxUTC, 'unixepoch') as MaxUTCMonth,\n"
+    "strftime('%e', MaxUTC, 'unixepoch') as MaxUTCDay,\n"
+    "MaxLocal,\n"
+    "strftime('%Y', MaxLocal, 'unixepoch') as MaxLocalYear,\n"
+    "strftime('%m', MaxLocal, 'unixepoch') as MaxLocalMonth,\n"
+    "strftime('%e', MaxLocal, 'unixepoch') as MaxLocalDay\n"
+    "FROM\n"
+    "(SELECT\n"
+    "unixepoch(min(time), 'unixepoch', 'start of ' || ?1) as MinUTC,\n"
+    "unixepoch(max(time), 'unixepoch', '+1 ' || ?1, 'start of ' || ?1, '-1 second') as MaxUTC,\n"
+    "unixepoch(min(time), 'unixepoch', 'localtime', 'start of ' || ?1) as MinLocal,\n"
+    "unixepoch(max(time), 'unixepoch', 'localtime', '+1 ' || ?1, 'start of ' || ?1, '-1 second') as MaxLocal\n"
+    "FROM env_data);";
+static sqlite3_stmt *DB_LIMITS_QUERY;
+void initialize_util_queries(sqlite3 *db) {
+    int status = sqlite3_prepare_v2(db, DB_LIMITS_QUERY_STR, -1,
+                                    &DB_LIMITS_QUERY, NULL);
+    if (status != SQLITE_OK) {
+        errx(1, "failed to compile limits query: %s", sqlite3_errstr(status));
+    }
+}
+
+void cleanup_util_queries() {
+    sqlite3_finalize(DB_LIMITS_QUERY);
+}
+
+bool get_database_limits(sqlite3 *db, const char *period, UtilDate *start,
+                         UtilDate *end) {
+    if (strcasecmp(period, "week") == 0 || strcasecmp(period, "hour") == 0) {
+        period = "day";
+    }
+    bool success = true;
+    sqlite3_bind_text(DB_LIMITS_QUERY, 1, period, -1, SQLITE_TRANSIENT);
+    int status = sqlite3_step(DB_LIMITS_QUERY);
+    if (status == SQLITE_ROW) {
+        if (start) {
+            start->utc = sqlite3_column_int64(DB_LIMITS_QUERY, 0);
+            start->utc_year = sqlite3_column_int64(DB_LIMITS_QUERY, 1);
+            start->utc_month = sqlite3_column_int64(DB_LIMITS_QUERY, 2);
+            start->utc_day = sqlite3_column_int64(DB_LIMITS_QUERY, 3);
+            start->local = sqlite3_column_int64(DB_LIMITS_QUERY, 4);
+            start->local_year = sqlite3_column_int64(DB_LIMITS_QUERY, 5);
+            start->local_month = sqlite3_column_int64(DB_LIMITS_QUERY, 6);
+            start->local_day = sqlite3_column_int64(DB_LIMITS_QUERY, 7);
+        }
+        if (end) {
+            end->utc = sqlite3_column_int64(DB_LIMITS_QUERY, 8);
+            end->utc_year = sqlite3_column_int64(DB_LIMITS_QUERY, 9);
+            end->utc_month = sqlite3_column_int64(DB_LIMITS_QUERY, 10);
+            end->utc_day = sqlite3_column_int64(DB_LIMITS_QUERY, 11);
+            end->local = sqlite3_column_int64(DB_LIMITS_QUERY, 12);
+            end->local_year = sqlite3_column_int64(DB_LIMITS_QUERY, 13);
+            end->local_month = sqlite3_column_int64(DB_LIMITS_QUERY, 14);
+            end->local_day = sqlite3_column_int64(DB_LIMITS_QUERY, 15);
+        }
+    } else {
+        success = false;
+    }
+    // unbind the string so it can be freed by the caller
+    sqlite3_bind_null(DB_LIMITS_QUERY, 1);
+    sqlite3_reset(DB_LIMITS_QUERY);
+    return success;
+}
diff --git a/src/util.h b/src/util.h
index b1ba2e6..fd32dc7 100644
--- a/src/util.h
+++ b/src/util.h
@@ -17,6 +17,7 @@
 #include <stdbool.h>
 #include <sys/types.h>
 #include <libgpio.h>
+#include <sqlite3.h>
 
 typedef struct {
     char *config_path; // path to config file
@@ -76,4 +77,37 @@ void *strdup_checked(const char *str);
  */
 #define LOG_VERBOSE(...) if (GLOBAL_OPTS.verbose) {fprintf(stderr, __VA_ARGS__);}
 
+/*
+ * Return: the number of days in month M. 1 is January. Y is the year.
+ */
+int days_in_month(int m, int y);
+
+/*
+ * Initialize SQL queries used by this file.
+ */
+void initialize_util_queries(sqlite3 *db);
+
+/*
+ * Cleanup SQL queries used by this file.
+ */
+void cleanup_util_queries(void);
+
+typedef struct {
+    int64_t utc;
+    int utc_year;
+    int utc_month;
+    int utc_day;
+    int64_t local;
+    int local_year;
+    int local_month;
+    int local_day;
+} UtilDate;
+
+/*
+ * Return the START of the first and END of the last PERIOD (ex. week) of DB.
+ * Return: false if an error occurred, true otherwise.
+ */
+bool get_database_limits(sqlite3 *db, const char *period, UtilDate *start,
+                         UtilDate *end);
+
 #endif