Fix SID syntax to use correct URL format without //

SID connections should use jdbc:oracle:thin:@host:port:SID (without
double slash), while service name connections use the thin-style
@//host:port/service_name format. Also return early when a custom
URL is provided.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: yahonda

README.md

@@ -132,7 +132,7 @@ plsql.connect! username: "hr", password: "hr", host: "localhost", database: "MYS
 If you need to connect using the legacy SID syntax (for Oracle databases older than 12c), prefix the database name with a colon:
 
 ```ruby
-# Connects using SID syntax: jdbc:oracle:thin:@//localhost:1521:MYSID
+# Connects using SID syntax: jdbc:oracle:thin:@localhost:1521:MYSID
 plsql.connect! username: "hr", password: "hr", host: "localhost", database: ":MYSID"
 ```
 

lib/plsql/jdbc_connection.rb

@@ -57,11 +57,19 @@ def self.jdbc_connection_url(params)
       if ENV["TNS_ADMIN"] && database && !params[:host] && !params[:url]
         "jdbc:oracle:thin:@#{database}"
       else
-        unless database =~ /^(:|\/)/
-          # assume database is a service name if no colon or slash are supplied
-          database = "/#{database}"
+        return params[:url] if params[:url]
+
+        host = params[:host] || "localhost"
+        port = params[:port] || 1521
+
+        if database =~ /^:/
+          # SID syntax: jdbc:oracle:thin:@host:port:SID
+          "jdbc:oracle:thin:@#{host}:#{port}#{database}"
+        else
+          # service name syntax: jdbc:oracle:thin:@//host:port/service_name
+          database = "/#{database}" unless database =~ /^\//
+          "jdbc:oracle:thin:@//#{host}:#{port}#{database}"
         end
-        params[:url] || "jdbc:oracle:thin:@//#{params[:host] || 'localhost'}:#{params[:port] || 1521}#{database}"
       end
     end
 

spec/plsql/connection_spec.rb

@@ -480,7 +480,7 @@
 
     it "should use SID syntax when database starts with colon" do
       url = PLSQL::JDBCConnection.jdbc_connection_url(host: "myhost", port: 1521, database: ":MYSID")
-      expect(url).to eq "jdbc:oracle:thin:@//myhost:1521:MYSID"
+      expect(url).to eq "jdbc:oracle:thin:@myhost:1521:MYSID"
     end
 
     it "should use service name syntax when database starts with slash" do