From 642bcccfac5037dfa6d62c660127752b9cff491c Mon Sep 17 00:00:00 2001
From: Markus Sauermann <6299227+Sauermann@users.noreply.github.com>
Date: Sat, 7 Dec 2024 23:40:54 +0100
Subject: [PATCH] Add support for multi-column primary keys

---
 README.md              |  4 ++--
 doc_classes/SQLite.xml |  4 ++--
 src/gdsqlite.cpp       | 30 +++++++++++++++++++++++++-----
 3 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/README.md b/README.md
index 90514a5..f261b6c 100644
--- a/README.md
+++ b/README.md
@@ -157,11 +157,11 @@ Additionally, a video tutorial by [Mitch McCollum (finepointcgi)](https://github
     - **"default"**: The default value of the column if not explicitly given.
 
     - **"primary_key"** *(default = false)*: Is this the primary key of this table?  
-    Evidently, only a single column can be set as the primary key.
+    Multiple columns can be set as a primary key.
 
     - **"auto_increment"** *(default = false)*: Automatically increment this column when no explicit value is given. This auto-generated value will be one more (+1) than the largest value currently in use.
 
-        ***NOTE**: Auto-incrementing a column only works when this column is the primary key!*
+        ***NOTE**: Auto-incrementing a column only works when this column is the primary key and no other columns are primary keys!*
 
     - **"foreign_key"**: Enforce an "exist" relationship between tables by setting this variable to `foreign_table.foreign_column`. In other words, when adding an additional row, the column value should be an existing value as found in the column with name `foreign_column` of the table with name `foreign_table`.
 
diff --git a/doc_classes/SQLite.xml b/doc_classes/SQLite.xml
index 2a8fa98..580f9bc 100644
--- a/doc_classes/SQLite.xml
+++ b/doc_classes/SQLite.xml
@@ -91,9 +91,9 @@
 				    * [i]Data types not found in this list throw an error and end up finalizing the current SQLite statement.[/i][br]    ** [i]with the question mark being replaced by the maximum amount of characters[/i]
 				[b]Optional fields[/b]:
 				- [b]"not_null"[/b] [i](default = false)[/i]: Is the NULL value an invalid value for this column?[br]- [b]"unique"[/b] [i](default = false)[/i]: Does the column have a unique constraint?[br]- [b]"default"[/b]: The default value of the column if not explicitly given.[br]- [b]"primary_key"[/b] [i](default = false)[/i]: Is this the primary key of this table?
-				    Evidently, only a single column can be set as the primary key.
+				    Multiple columns can be set as a primary key.
 				- [b]"auto_increment"[/b] [i](default = false)[/i]: Automatically increment this column when no explicit value is given. This auto-generated value will be one more (+1) than the largest value currently in use.
-				    [i][b]NOTE[/b]: Auto-incrementing a column only works when this column is the primary key![/i]
+				    [i][b]NOTE[/b]: Auto-incrementing a column only works when this column is the primary key and no other columns are primary keys![/i]
 				- [b]"foreign_key"[/b]: Enforce an "exist" relationship between tables by setting this variable to [code]foreign_table.foreign_column[/code]. In other words, when adding an additional row, the column value should be an existing value as found in the column with name [code]foreign_column[/code] of the table with name [code]foreign_table[/code].
 				    [i][b]NOTE[/b]: Availability of foreign keys has to be enabled by setting the [code]foreign_keys[/code]-variable to true BEFORE opening the database.[/i]
 				[b]Example usage[/b]:
diff --git a/src/gdsqlite.cpp b/src/gdsqlite.cpp
index f408da8..8b4ad22 100644
--- a/src/gdsqlite.cpp
+++ b/src/gdsqlite.cpp
@@ -335,15 +335,23 @@ bool SQLite::create_table(const String &p_name, const Dictionary &p_table_dict)
 		return false;
 	}
 
-	String query_string, type_string, key_string;
+	String query_string, type_string, key_string, primary_string;
 	String integer_datatype = "int";
 	/* Create SQL statement */
 	query_string = "CREATE TABLE IF NOT EXISTS " + p_name + " (";
 	key_string = "";
+	primary_string = "";
 
 	Dictionary column_dict;
 	Array columns = p_table_dict.keys();
 	int64_t number_of_columns = columns.size();
+	int primary_key_columns = 0;
+	for (int64_t i = 0; i <= number_of_columns - 1; i++) {
+		column_dict = p_table_dict[columns[i]];
+		if (column_dict.get("primary_key", false)) {
+			primary_key_columns++;
+		}
+	}
 	for (int64_t i = 0; i <= number_of_columns - 1; i++) {
 		column_dict = p_table_dict[columns[i]];
 		query_string += (const String &)columns[i] + String(" ");
@@ -356,10 +364,18 @@ bool SQLite::create_table(const String &p_name, const Dictionary &p_table_dict)
 
 		/* Primary key check */
 		if (column_dict.get("primary_key", false)) {
-			query_string += String(" PRIMARY KEY");
-			/* Autoincrement check */
-			if (column_dict.get("auto_increment", false)) {
-				query_string += String(" AUTOINCREMENT");
+			if (primary_key_columns == 1) {
+				query_string += String(" PRIMARY KEY");
+				/* Autoincrement check */
+				if (column_dict.get("auto_increment", false)) {
+					query_string += String(" AUTOINCREMENT");
+				}
+			} else {
+				if (primary_string.is_empty()) {
+					primary_string = (const String &)columns[i];
+				} else {
+					primary_string += String(", ") + (const String &)columns[i];
+				}
 			}
 		}
 		/* Not null check */
@@ -393,6 +409,10 @@ bool SQLite::create_table(const String &p_name, const Dictionary &p_table_dict)
 		}
 	}
 
+	if (primary_key_columns > 1) {
+		query_string += String(", PRIMARY KEY (") + primary_string + String(")");
+	}
+
 	query_string += key_string + ");";
 
 	return query(query_string);