feat: SQL 语法支持 BETWEEN AND、DROP TABLE IF EXISTS

dist/metona-sqlark.js

@@ -1616,6 +1616,11 @@
             return this.engine.createTable(createSchema(stmt.name, columns));
         }
         async executeDropTable(stmt) {
+            if (stmt.ifExists) {
+                const exists = await this.engine.hasTable(stmt.name);
+                if (!exists)
+                    return; // IF EXISTS: 表不存在时静默返回
+            }
             return this.engine.dropTable(stmt.name);
         }
         getEngine() { return this.engine; }
@@ -1768,6 +1773,9 @@
         TokenType["TRUE"] = "TRUE";
         TokenType["REFERENCES"] = "REFERENCES";
         TokenType["CASCADE"] = "CASCADE";
+        TokenType["BETWEEN"] = "BETWEEN";
+        TokenType["IF"] = "IF";
+        TokenType["EXISTS"] = "EXISTS";
         TokenType["FALSE"] = "FALSE";
         // JOIN 相关
         TokenType["INNER"] = "INNER";
@@ -1844,6 +1852,9 @@
         'FALSE': TokenType.FALSE,
         'REFERENCES': TokenType.REFERENCES,
         'CASCADE': TokenType.CASCADE,
+        'BETWEEN': TokenType.BETWEEN,
+        'IF': TokenType.IF,
+        'EXISTS': TokenType.EXISTS,
         // JOIN
         'INNER': TokenType.INNER,
         'LEFT': TokenType.LEFT,
@@ -2453,8 +2464,15 @@
         parseDropTable() {
             this.expect(TokenType.DROP);
             this.expect(TokenType.TABLE);
+            // IF EXISTS（可选）
+            let ifExists = false;
+            if (this.curTokenIs(TokenType.IF)) {
+                this.nextToken();
+                this.expect(TokenType.EXISTS);
+                ifExists = true;
+            }
             const tableName = this.expectIdentifier('table name');
-            return { type: 'DROP_TABLE', name: tableName };
+            return { type: 'DROP_TABLE', name: tableName, ifExists: ifExists || undefined };
         }
         // ===================================================================
         //  条件表达式
@@ -2505,6 +2523,27 @@
                 result[column] = isNot ? { $ne: null } : { $eq: null };
                 return result;
             }
+            // BETWEEN val1 AND val2
+            if (this.curTokenIs(TokenType.BETWEEN)) {
+                this.nextToken();
+                const low = this.parseValue();
+                this.expect(TokenType.AND);
+                const high = this.parseValue();
+                const result = {};
+                result[column] = { $gte: low, $lte: high };
+                return result;
+            }
+            // NOT BETWEEN val1 AND val2
+            if (this.curTokenIs(TokenType.NOT) && this.peekTokenIs(TokenType.BETWEEN)) {
+                this.nextToken(); // skip NOT
+                this.nextToken(); // skip BETWEEN
+                const low = this.parseValue();
+                this.expect(TokenType.AND);
+                const high = this.parseValue();
+                const result = {};
+                result[column] = { $not: { $gte: low, $lte: high } };
+                return result;
+            }
             // NOT LIKE / NOT IN（NOT 后紧跟 LIKE 或 IN）
             if (this.curTokenIs(TokenType.NOT)) {
                 if (this.peekTokenIs(TokenType.IN)) {