fix(schema-engine): combine foreign_keys + defer_foreign_keys PRAGMAs…

… to fix prisma/prisma#24208

schema-engine/connectors/sql-schema-connector/src/sql_renderer/sqlite_renderer.rs

@@ -183,14 +183,21 @@ impl SqlRenderer for SqliteFlavour {
     }
 
     fn render_redefine_tables(&self, tables: &[RedefineTable], schemas: MigrationPair<&SqlSchema>) -> Vec<String> {
-        // Based on 'Making Other Kinds Of Table Schema Changes' from https://www.sqlite.org/lang_altertable.html
-        let mut result = vec!["PRAGMA foreign_keys=OFF".to_string()];
+        // Based on 'Making Other Kinds Of Table Schema Changes' from https://www.sqlite.org/lang_altertable.html,
+        // and on https://developers.cloudflare.com/d1/reference/database-commands/#pragma-defer_foreign_keys--onoff.
+        let mut result: Vec<String> = vec![];
+
+        // disables foreign key constraint enforcement
+        result.push("PRAGMA defer_foreign_keys=ON".to_string());
+        result.push("PRAGMA foreign_keys=OFF".to_string());
+
         let mut foreign_key_checks = vec![];
 
         for redefine_table in tables {
             let tables = schemas.walk(redefine_table.table_ids);
             let temporary_table_name = format!("new_{}", &tables.next.name());
 
+            // maybe use render_create_table_for_migration?
             result.push(self.render_create_table_as(
                 tables.next,
                 QuotedWithPrefix(None, Quoted::sqlite_ident(&temporary_table_name)),
@@ -218,9 +225,13 @@ impl SqlRenderer for SqliteFlavour {
             ));
         }
 
-        result.extend(foreign_key_checks);
+        // Checks the database for foreign key constraint violations.
+        // Note: this code is probably useless, pending foreign constraint violations are checked fine even without it.
+        // result.extend(foreign_key_checks);
 
+        // resumes immediate enforcement of foreign key constraints.
         result.push("PRAGMA foreign_keys=ON".to_string());
+        result.push("PRAGMA defer_foreign_keys=OFF".to_string());
 
         result
     }