# 转义查询中的保留关键字
<a name="reserved-words"></a>

当您在 Athena 中运行包含保留关键字的查询时，必须用特殊字符将保留关键字括起来以便对它们进行转义。可使用本主题中的列表检查 Athena 中保留的关键字。

要对 DDL 语句中的保留关键字进行转义，请使用反引号 (`) 将其括起来。要对 SQL `SELECT` 语句以及[视图](views.md)的查询中的保留关键字进行转义，请使用双引号 ('') 将其括起来。
+  [要在 DDL 语句中转义的保留关键字](#list-of-ddl-reserved-words) 
+  [要在 SQL SELECT 语句中转义的保留关键字](#list-of-reserved-words-sql-select) 
+  [保留关键字的查询示例](#examples-reserved-words) 

## 要在 DDL 语句中转义的保留关键字
<a name="list-of-ddl-reserved-words"></a>

Athena 在其 DDL 语句中使用以下保留关键字列表。如果您未经转义即使用它们，Athena 会发出错误。要进行转义，请使用反引号 (`) 将其括起来。

如果未使用反引号 (`) 将 DDL 保留关键字括起来，则不能在 DDL 语句中将这些保留关键字用作标识符名称。

```
ALL, ALTER, AND, ARRAY, AS, AUTHORIZATION, BETWEEN, BIGINT, 
BINARY, BOOLEAN, BOTH, BY, CASE, CASHE, CAST, CHAR, COLUMN, 
CONF, CONSTRAINT, COMMIT, CREATE, CROSS, CUBE, CURRENT, 
CURRENT_DATE, CURRENT_TIMESTAMP, CURSOR, DATABASE, DATE, 
DAYOFWEEK, DECIMAL, DELETE, DESCRIBE, DISTINCT, DIV, DOUBLE, 
DROP, ELSE, END, EXCHANGE, EXISTS, EXTENDED, EXTERNAL, EXTRACT, 
FALSE, FETCH, FLOAT, FLOOR, FOLLOWING, FOR, FOREIGN, FROM, 
FULL, FUNCTION, GRANT, GROUP, GROUPING, HAVING, IF, IMPORT, 
IN, INNER, INSERT, INT, INTEGER, INTERSECT, INTERVAL, INTO, 
IS, JOIN, LATERAL, LEFT, LESS, LIKE, LOCAL, MACRO, MAP, MORE, 
NONE, NOT, NULL, NUMERIC, OF, ON, ONLY, OR, ORDER, OUT, 
OUTER, OVER, PARTIALSCAN, PARTITION, PERCENT, PRECEDING, 
PRECISION, PRESERVE, PRIMARY, PROCEDURE, RANGE, READS, 
REDUCE, REGEXP, REFERENCES, REVOKE, RIGHT, RLIKE, ROLLBACK, 
ROLLUP, ROW, ROWS, SELECT, SET, SMALLINT, START,TABLE, 
TABLESAMPLE, THEN, TIME, TIMESTAMP, TO, TRANSFORM, TRIGGER, 
TRUE, TRUNCATE, UNBOUNDED,UNION, UNIQUEJOIN, UPDATE, USER, 
USING, UTC_TIMESTAMP, VALUES, VARCHAR, VIEWS, WHEN, WHERE, 
WINDOW, WITH
```

## 要在 SQL SELECT 语句中转义的保留关键字
<a name="list-of-reserved-words-sql-select"></a>

Athena 在 SQL `SELECT` 语句以及视图查询中使用以下保留关键字列表。

如果您将这些关键字用作标识符，则必须在查询语句中使用双引号 (") 将它们括起来。

```
ALTER, AND, AS, BETWEEN, BY, CASE, CAST, CONSTRAINT, CREATE, 
CROSS, CUBE, CURRENT_CATALOG, CURRENT_DATE, CURRENT_PATH, 
CURRENT_SCHEMA, CURRENT_TIME, CURRENT_TIMESTAMP, CURRENT_USER, 
DEALLOCATE, DELETE, DESCRIBE, DISTINCT, DROP, ELSE, END, ESCAPE, 
EXCEPT, EXECUTE, EXISTS, EXTRACT, FALSE, FIRST, FOR, FROM, 
FULL, GROUP, GROUPING, HAVING, IN, INNER, INSERT, INTERSECT, 
INTO, IS, JOIN, JSON_ARRAY, JSON_EXISTS, JSON_OBJECT, 
JSON_QUERY, JSON_TABLE, JSON_VALUE, LAST, LEFT, LIKE, 
LISTAGG, LOCALTIME, LOCALTIMESTAMP, NATURAL, NORMALIZE, 
NOT, NULL, OF, ON, OR, ORDER, OUTER, PREPARE, RECURSIVE, RIGHT, 
ROLLUP, SELECT, SKIP, TABLE, THEN, TRIM, TRUE, UESCAPE, UNION, 
UNNEST, USING, VALUES, WHEN, WHERE, WITH
```

## 保留关键字的查询示例
<a name="examples-reserved-words"></a>

以下示例中的查询使用反引号 (`) 来转义 DDL 相关的保留关键字 *partition* 和 *date*（用于表名称和其中一个列名称）：

```
CREATE EXTERNAL TABLE `partition` (
`date` INT, 
col2 STRING
)
PARTITIONED BY (year STRING)
STORED AS TEXTFILE
LOCATION 's3://amzn-s3-demo-bucket/test_examples/';
```

以下示例查询包含一个列名称，此列名称在 `ALTER TABLE ADD PARTITION` 和 `ALTER TABLE DROP PARTITION` 语句中包含 DDL 相关的保留关键字。DDL 保留关键字括在反引号 (`) 中：

```
ALTER TABLE test_table 
ADD PARTITION (`date` = '2018-05-14')
```

```
ALTER TABLE test_table 
DROP PARTITION (`partition` = 'test_partition_value')
```

以下查询示例包含一个保留关键字 (end) 作为 `SELECT` 语句中的标识符。此关键字用双引号进行转义：

```
SELECT * 
FROM TestTable
WHERE "end" != nil;
```

以下查询示例在 `SELECT` 语句中包含一个保留关键字 (first)。此关键字用双引号进行转义：

```
SELECT "itemId"."first" 
FROM testTable 
LIMIT 10;
```