diff --git a/tag.sh b/tag.sh
index e6f6eb6..e6bde3c 100755
--- a/tag.sh
+++ b/tag.sh
@@ -77,13 +77,14 @@ add() {
     # $TYPE(tag|path|hash) $VALUE1..$VALUEN
     [ "$1" = "tag" ] && shift && add_tag "$@" && exit 0
     [ "$1" = "path" ] && shift && add_path "$@" && exit 0
-    [ "$1" = "hash" ] && fail "Adding hashes is not implemented yet." && TABLE="hashes" && COLUMN="md5,filename"
-    exit 0
+    [ "$1" = "hash" ] && shift && add_hash "$@" && exit 0
+    [ "$1" = "file" ] && fail "Use \"$SCRIPT_NAME add path\" instead."
+    fail "Usage: $SCRIPT_NAME add tag/path/hash"
 }
 
 sqlite_query() {
     # $QUERY
-    sqlite3 -table "$DB_FILE" "$1"
+    sqlite3 "$DB_FILE" "$1"
 }
 
 sqlite_lastrows() {
@@ -91,7 +92,7 @@ sqlite_lastrows() {
     sqlite_query "SELECT * FROM \"$1\" ORDER BY id DESC LIMIT ${2}"
 }
 
-sqlite_insert() {
+sqlite_insert_single() {
     # $TABLE $COLUMN $VALUES
     # $VALUES can be comma-delimited
     [ -z "$1" ] && fail "No table specified."
@@ -108,7 +109,29 @@ sqlite_insert() {
             VALUES+=",(\"$1\")"
         done
     fi
-    QUERY="INSERT INTO $TABLE ($COLUMN) VALUES ${VALUES} RETURNING *;"
+    QUERY="PRAGMA foreign_keys=ON;"
+    QUERY+="INSERT INTO $TABLE ($COLUMN) VALUES ${VALUES} RETURNING *;"
+    sqlite_query "$QUERY"
+}
+
+sqlite_insert_multi() {
+    # $TABLE $COLUMN $VALUE1 $VALUE2
+    [ -z "$1" ] && fail "No table specified."
+    TABLE="$1"
+    [ -z "$2" ] && fail "No column(s) supplied."
+    COLUMN="$2"
+    [[ -z "$3" || -z "$4" ]] && fail "No column values supplied."
+    shift 2
+    VALUES="($1,$2)"
+    if [[ ! -z "${3:-}" && ! -z "${4:-}" ]]; then
+        while true; do
+            shift
+            [ -z "${1:-}" && -z "${2:-}" ] && break
+            VALUES+=",($1,$2)"
+        done
+    fi
+    QUERY="PRAGMA foreign_keys=ON;"
+    QUERY+="INSERT INTO $TABLE ($COLUMN) VALUES ${VALUES} RETURNING *;"
     sqlite_query "$QUERY"
 }
 
@@ -116,14 +139,25 @@ add_tag() {
     # $TAG1...$TAGN
     TABLE="tags"
     COLUMN="label"
-    sqlite_insert "$TABLE" "$COLUMN" "$@"
+    sqlite_insert_single "$TABLE" "$COLUMN" "$@"
 }
 
 add_path() {
     # $PATH1..$PATHN
     TABLE="files"
     COLUMN="filename"
-    sqlite_insert "$TABLE" "$COLUMN" "$@"
+    sqlite_insert_single "$TABLE" "$COLUMN" "$@"
+}
+
+add_hash() {
+    # $FILE $HASH 
+    TABLE="hashes"
+    COLUMN="fid,md5"
+    local FILENAME="${1:-}"
+    [ -z "$FILENAME" ] && fail "No file specified."
+    RESULT=$(sqlite_query "SELECT id FROM files WHERE filename = '$FILENAME'")
+    [ -z "$RESULT" ] && fail "File \"$FILENAME\" does not exist in database."
+    sqlite_insert_multi "$TABLE" "$COLUMN" $RESULT "'$2'" 
 }
 
 add_path_auto() {