Database: use schema_version and application_id

sql/v01/10.create.sql

@@ -1,16 +1,8 @@
 
+PRAGMA application_id = 0x454C5747;  -- ASCII: "ELWG"
+PRAGMA user_version = 0;  -- Product version. 4-byte integer: 1st - major, 2nd - minor, 3rd+4th - patch
 PRAGMA foreign_keys = ON;
 
-CREATE TABLE meta (
-    name  TEXT NOT NULL CHECK (name REGEXP '^[a-z_]+$'),
-    value TEXT NOT NULL,
-
-    CONSTRAINT pk_meta PRIMARY KEY (name)
-) STRICT;
-
-INSERT INTO meta (name, value)
-VALUES ('schema_version', '1');
-
 CREATE TABLE client_parameter (
     param TEXT NOT NULL CHECK (param REGEXP '^[A-Z_]+$'),
     value TEXT,

sql/v01/99.schema_version.sql

@@ -0,0 +1,2 @@
+
+PRAGMA schema_version = 100;  -- This value MUST NOT be changed while other connections are open!

wgmaster/import.py

@@ -117,6 +117,7 @@ def main() -> None:
             with open(file_name, encoding='utf-8') as sql_file:
                 print(f'Executing {file_name}')
                 cnx.executescript(sql_file.read())
+    ver = cnx.execute("PRAGMA schema_version").fetchall()[0][0]
 
     try:
         cnx.isolation_level = None
@@ -129,6 +130,7 @@ def main() -> None:
             raise RuntimeError('foreign key constraint failed')
         cnx.execute("COMMIT")
         cnx.execute("VACUUM")
+        cnx.execute(f"PRAGMA schema_version = {ver}")
     except Exception as err:
         cnx.execute("ROLLBACK")
         raise err