fix: ALTER TABLE DROP COLUMN preserves all row data — no longer drops+recreates table

dist/metona-sqlark.cjs.js

@@ -5660,17 +5660,23 @@ class QueryExecutor {
             if (schema.columns[stmt.column.name]) {
                 throw new DatabaseError(`Column "${stmt.column.name}" already exists in table "${stmt.name}"`, 'COLUMN_EXISTS');
             }
+            // 直接在 schema 引用上添加列（已有行的该列值为 undefined/default）
             schema.columns[stmt.column.name] = astColumnToColumnDef(stmt.column);
         }
         else if (stmt.action === 'DROP') {
             if (!schema.columns[stmt.column.name]) {
                 throw new DatabaseError(`Column "${stmt.column.name}" does not exist in table "${stmt.name}"`, 'COLUMN_NOT_FOUND');
             }
+            // 从 schema 引用上删除列定义（保留所有行数据）
             delete schema.columns[stmt.column.name];
+            // 清除已有行中该列的值（MemoryEngine 的 find 返回引用，delete 直接生效）
+            const rows = await this.engine.find(stmt.name, { table: stmt.name });
+            const colName = stmt.column.name;
+            for (const row of rows) {
+                if (colName in row)
+                    delete row[colName];
+            }
         }
-        // 重建表结构
-        await this.engine.dropTable(stmt.name);
-        await this.engine.createTable(schema);
     }
     async executeTruncateTable(stmt) {
         const exists = await this.engine.hasTable(stmt.name);

dist/metona-sqlark.esm.js

@@ -5656,17 +5656,23 @@ class QueryExecutor {
             if (schema.columns[stmt.column.name]) {
                 throw new DatabaseError(`Column "${stmt.column.name}" already exists in table "${stmt.name}"`, 'COLUMN_EXISTS');
             }
+            // 直接在 schema 引用上添加列（已有行的该列值为 undefined/default）
             schema.columns[stmt.column.name] = astColumnToColumnDef(stmt.column);
         }
         else if (stmt.action === 'DROP') {
             if (!schema.columns[stmt.column.name]) {
                 throw new DatabaseError(`Column "${stmt.column.name}" does not exist in table "${stmt.name}"`, 'COLUMN_NOT_FOUND');
             }
+            // 从 schema 引用上删除列定义（保留所有行数据）
             delete schema.columns[stmt.column.name];
+            // 清除已有行中该列的值（MemoryEngine 的 find 返回引用，delete 直接生效）
+            const rows = await this.engine.find(stmt.name, { table: stmt.name });
+            const colName = stmt.column.name;
+            for (const row of rows) {
+                if (colName in row)
+                    delete row[colName];
+            }
         }
-        // 重建表结构
-        await this.engine.dropTable(stmt.name);
-        await this.engine.createTable(schema);
     }
     async executeTruncateTable(stmt) {
         const exists = await this.engine.hasTable(stmt.name);

dist/metona-sqlark.js

@@ -5662,17 +5662,23 @@
                 if (schema.columns[stmt.column.name]) {
                     throw new DatabaseError(`Column "${stmt.column.name}" already exists in table "${stmt.name}"`, 'COLUMN_EXISTS');
                 }
+                // 直接在 schema 引用上添加列（已有行的该列值为 undefined/default）
                 schema.columns[stmt.column.name] = astColumnToColumnDef(stmt.column);
             }
             else if (stmt.action === 'DROP') {
                 if (!schema.columns[stmt.column.name]) {
                     throw new DatabaseError(`Column "${stmt.column.name}" does not exist in table "${stmt.name}"`, 'COLUMN_NOT_FOUND');
                 }
+                // 从 schema 引用上删除列定义（保留所有行数据）
                 delete schema.columns[stmt.column.name];
+                // 清除已有行中该列的值（MemoryEngine 的 find 返回引用，delete 直接生效）
+                const rows = await this.engine.find(stmt.name, { table: stmt.name });
+                const colName = stmt.column.name;
+                for (const row of rows) {
+                    if (colName in row)
+                        delete row[colName];
+                }
             }
-            // 重建表结构
-            await this.engine.dropTable(stmt.name);
-            await this.engine.createTable(schema);
         }
         async executeTruncateTable(stmt) {
             const exists = await this.engine.hasTable(stmt.name);

src/query/executor.ts

@@ -300,16 +300,21 @@ export class QueryExecutor {
       if (schema.columns[stmt.column.name]) {
         throw new DatabaseError(`Column "${stmt.column.name}" already exists in table "${stmt.name}"`, 'COLUMN_EXISTS');
       }
+      // 直接在 schema 引用上添加列（已有行的该列值为 undefined/default）
       schema.columns[stmt.column.name] = astColumnToColumnDef(stmt.column);
     } else if (stmt.action === 'DROP') {
       if (!schema.columns[stmt.column.name]) {
         throw new DatabaseError(`Column "${stmt.column.name}" does not exist in table "${stmt.name}"`, 'COLUMN_NOT_FOUND');
       }
+      // 从 schema 引用上删除列定义（保留所有行数据）
       delete schema.columns[stmt.column.name];
+      // 清除已有行中该列的值（MemoryEngine 的 find 返回引用，delete 直接生效）
+      const rows = await this.engine.find(stmt.name, { table: stmt.name });
+      const colName = stmt.column.name;
+      for (const row of rows) {
+        if (colName in row) delete row[colName];
+      }
     }
-    // 重建表结构
-    await this.engine.dropTable(stmt.name);
-    await this.engine.createTable(schema);
   }
 
   private async executeTruncateTable(stmt: TruncateTableStatement): Promise<void> {