option allowEmptyValue flag

packages/tools/src/diffTools.ts

@@ -435,7 +435,11 @@ function planChangeTableOptions(plan: AlterPlan, oldTable: TableInfo, newTable:
       continue;
     }
     const name = option.name;
-    if (oldTable[name] != newTable[name] && (oldTable[name] || newTable[name])) {
+    if (
+      oldTable[name] != newTable[name] &&
+      (oldTable[name] || newTable[name]) &&
+      (newTable[name] || option.allowEmptyValue)
+    ) {
       plan.setTableOption(newTable, name, newTable[name]);
     }
   }

packages/types/dialect.d.ts

@@ -54,5 +54,6 @@ export interface SqlDialect {
     name: string;
     sqlFormatString: string;
     disabled?: boolean;
+    allowEmptyValue?: boolean;
   }[];
 }

plugins/dbgate-plugin-clickhouse/src/frontend/driver.js

@@ -128,6 +128,7 @@ const dialect = {
         label: 'Comment',
         name: 'objectComment',
         sqlFormatString: '^comment %v',
+        allowEmptyValue: true,
       },
     ];
   },

plugins/dbgate-plugin-mysql/src/frontend/drivers.js

@@ -118,6 +118,7 @@ const dialect = {
         label: 'Comment',
         name: 'objectComment',
         sqlFormatString: '^comment = %v',
+        allowEmptyValue: true,
       },
     ];
   },