# SQL > 译者：[flink.sojb.cn](https://flink.sojb.cn/) SQL查询是使用`sqlQuery()`方法指定的`TableEnvironment`。该方法返回SQL查询的结果为`Table`。A `Table`可以在[后续的SQL和 Table API查询中使用](common.html#mixing-table-api-and-sql)，可以[转换为DataSet或DataStream](common.html#integration-with-datastream-and-dataset-api)，也可以[写入TableSink](common.html#emit-a-table)）。SQL和 Table API查询可以无缝混合，并进行整体优化并转换为单个程序。 要访问SQL查询中的表，必须[在TableEnvironment中注册](common.html#register-tables-in-the-catalog)它。可以从[TableSource](common.html#register-a-tablesource)，[Table](common.html#register-a-table)，[DataStream或DataSet](common.html#register-a-datastream-or-dataset-as-table) [注册表](common.html#register-a-tablesource)。或者，用户还可以[在TableEnvironment中注册外部目录](common.html#register-an-external-catalog)以指定数据源的位置。 为方便起见，`Table.toString()`自动在其中以唯一名称注册表`TableEnvironment`并返回名称。因此，`Table`对象可以直接内联到SQL查询中（通过字符串连接），如下面的示例所示。 **注意：** Flink的SQL支持尚未完成。包含不受支持的SQL函数的查询会导致a `TableException`。以下部分列出了批处理和流表上SQL的受支持函数。 ## 指定查询 以下示例显示如何在已注册和内联表中指定SQL查询。 * [**Java**](#tab_java_0) * [**Scala**](#tab_scala_0) ``` StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment(); StreamTableEnvironment tableEnv = TableEnvironment.getTableEnvironment(env); // ingest a DataStream from an external source DataStream> ds = env.addSource(...); // SQL query with an inlined (unregistered) table Table table = tableEnv.toTable(ds, "user, product, amount"); Table result = tableEnv.sqlQuery( "SELECT SUM(amount) FROM " + table + " WHERE product LIKE '%Rubber%'"); // SQL query with a registered table // register the DataStream as table "Orders" tableEnv.registerDataStream("Orders", ds, "user, product, amount"); // run a SQL query on the Table and retrieve the result as a new Table Table result2 = tableEnv.sqlQuery( "SELECT product, amount FROM Orders WHERE product LIKE '%Rubber%'"); // SQL update with a registered table // create and register a TableSink TableSink csvSink = new CsvTableSink("/path/to/file", ...); String[] fieldNames = {"product", "amount"}; TypeInformation[] fieldTypes = {Types.STRING, Types.INT}; tableEnv.registerTableSink("RubberOrders", fieldNames, fieldTypes, csvSink); // run a SQL update query on the Table and emit the result to the TableSink tableEnv.sqlUpdate( "INSERT INTO RubberOrders SELECT product, amount FROM Orders WHERE product LIKE '%Rubber%'"); ``` ``` val env = StreamExecutionEnvironment.getExecutionEnvironment val tableEnv = TableEnvironment.getTableEnvironment(env) // read a DataStream from an external source val ds: DataStream[(Long, String, Integer)] = env.addSource(...) // SQL query with an inlined (unregistered) table val table = ds.toTable(tableEnv, 'user, 'product, 'amount) val result = tableEnv.sqlQuery( s"SELECT SUM(amount) FROM $table WHERE product LIKE '%Rubber%'") // SQL query with a registered table // register the DataStream under the name "Orders" tableEnv.registerDataStream("Orders", ds, 'user, 'product, 'amount) // run a SQL query on the Table and retrieve the result as a new Table val result2 = tableEnv.sqlQuery( "SELECT product, amount FROM Orders WHERE product LIKE '%Rubber%'") // SQL update with a registered table // create and register a TableSink TableSink csvSink = new CsvTableSink("/path/to/file", ...) val fieldNames: Array[String] = Array("product", "amount") val fieldTypes: Array[TypeInformation[_]] = Array(Types.STRING, Types.INT) tableEnv.registerTableSink("RubberOrders", fieldNames, fieldTypes, csvSink) // run a SQL update query on the Table and emit the result to the TableSink tableEnv.sqlUpdate( "INSERT INTO RubberOrders SELECT product, amount FROM Orders WHERE product LIKE '%Rubber%'") ``` ## 支持的语法 Flink使用[Apache Calcite](https://calcite.apache.org/docs/reference.html)解析SQL ，它支持标准的ANSI SQL。Flink不支持DDL语句。 以下BNF语法描述了批处理和流式查询中支持的SQL函数的超集。“ [算子”](#operations)部分显示支持的函数的示例，并指示仅批处理或流式查询支持哪些函数。 ``` insert: INSERT INTO tableReference query query: values | { select | selectWithoutFrom | query UNION [ ALL ] query | query EXCEPT query | query INTERSECT query } [ ORDER BY orderItem [, orderItem ]* ] [ LIMIT { count | ALL } ] [ OFFSET start { ROW | ROWS } ] [ FETCH { FIRST | NEXT } [ count ] { ROW | ROWS } ONLY] orderItem: expression [ ASC | DESC ] select: SELECT [ ALL | DISTINCT ] { * | projectItem [, projectItem ]* } FROM tableExpression [ WHERE booleanExpression ] [ GROUP BY { groupItem [, groupItem ]* } ] [ HAVING booleanExpression ] [ WINDOW windowName AS windowSpec [, windowName AS windowSpec ]* ] selectWithoutFrom: SELECT [ ALL | DISTINCT ] { * | projectItem [, projectItem ]* } projectItem: expression [ [ AS ] columnAlias ] | tableAlias . * tableExpression: tableReference [, tableReference ]* | tableExpression [ NATURAL ] [ LEFT | RIGHT | FULL ] JOIN tableExpression [ joinCondition ] joinCondition: ON booleanExpression | USING '(' column [, column ]* ')' tableReference: tablePrimary [ [ AS ] alias [ '(' columnAlias [, columnAlias ]* ')' ] ] tablePrimary: [ TABLE ] [ [ catalogName . ] schemaName . ] tableName | LATERAL TABLE '(' functionName '(' expression [, expression ]* ')' ')' | UNNEST '(' expression ')' values: VALUES expression [, expression ]* groupItem: expression | '(' ')' | '(' expression [, expression ]* ')' | CUBE '(' expression [, expression ]* ')' | ROLLUP '(' expression [, expression ]* ')' | GROUPING SETS '(' groupItem [, groupItem ]* ')' windowRef: windowName | windowSpec windowSpec: [ windowName ] '(' [ ORDER BY orderItem [, orderItem ]* ] [ PARTITION BY expression [, expression ]* ] [ RANGE numericOrIntervalExpression {PRECEDING} | ROWS numericExpression {PRECEDING} ] ')' ``` Flink SQL对类似于Java标识符（表，属性，函数名）使用词法策略： * 无论是否引用标识符，都会保存标识符的大小写。 * 之后，标识符区分大小写。 * 与Java不同，反向标记允许标识符包含非字母数字字符（例如`"SELECT a AS `my field` FROM t"`）。 ## 算子 ### Scan，Projection和过滤 --- 操作：**Scan/Select/As** 批量 流 描述： ``` SELECT * FROM Orders SELECT a, c AS d FROM Orders ``` --- 操作：**Where / Filter** Batch Streaming 描述： ``` SELECT * FROM Orders WHERE b = 'red' SELECT * FROM Orders WHERE a % 2 = 0 ``` --- 操作：**User-defined Scalar Functions (Scalar UDF)** 批量 流 描述：UDF必须在TableEnvironment中注册。有关如何指定和注册标量UDF的详细信息，请参阅[UDF文档](udfs.html)。 ``` SELECT PRETTY_PRINT(user) FROM Orders ``` ### 聚合 | **GroupBy聚合** 批处理 流 结果更新 | **注意：**流表上的GroupBy会生成更新结果。有关详细信息，请参阅[Streaming Concepts](streaming.html)页面。 ``` SELECT a, SUM(b) as d FROM Orders GROUP BY a ``` --- 操作：**GroupBy窗口聚合** 批量 流 描述：使用组窗口计算每个组的单个结果行。有关详细信息，请参阅[GroupWindows](#group-windows)部分。 ``` SELECT user, SUM(amount) FROM Orders GROUP BY TUMBLE(rowtime, INTERVAL '1' DAY), user ``` --- 操作：**Over Window聚合** 流 描述：**注意：**必须在同一窗口中定义所有聚合，即相同的分区，排序和范围。目前，仅支持具有PRREDING（UNBOUNDED和有界）到CURRENT ROW范围的窗口。尚不支持使用FOLLOWING的范围。必须在单个[时间属性](streaming.html#time-attributes)上指定ORDER BY[](streaming.html#time-attributes) ``` SELECT COUNT(amount) OVER ( PARTITION BY user ORDER BY proctime ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) FROM Orders SELECT COUNT(amount) OVER w, SUM(amount) OVER w FROM Orders WINDOW w AS ( PARTITION BY user ORDER BY proctime ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) ``` | **Distinct** 批量 流 结果更新 | ``` SELECT DISTINCT users FROM Orders ``` **注意：**对于流式查询，计算查询结果所需的状态可能会无限增长，具体取决于不同字段的数量。请提供具有有效保存间隔的查询配置，以防止过大的状态。有关详细信息，请参阅[Streaming Concepts](streaming.html)。 --- 操作：**分组集，汇总，多维数据集** 批量 描述： ``` SELECT SUM(amount) FROM Orders GROUP BY GROUPING SETS ((user), (product)) ``` --- 操作：**Having** 批量 流 描述： ``` SELECT SUM(amount) FROM Orders GROUP BY users HAVING SUM(amount) > 50 ``` --- 操作：**用户定义的聚合函数（UDAGG）** 批量 流 描述：UDAGG必须在TableEnvironment中注册。有关如何指定和注册UDAGG的详细信息，请参阅[UDF文档](udfs.html)。 ``` SELECT MyAggregate(amount) FROM Orders GROUP BY users ``` ### Join --- 操作：**内部Equi-join** 批量 流 描述：目前，仅支持等连接，即具有至少一个带有等式谓词的连接条件的连接。不支持任意交叉或theta连接。**注意：**连接顺序未优化。表按照FROM子句中指定的顺序连接。确保以不产生交叉连接（笛卡尔积）的顺序指定表，这些表不受支持并且会导致查询失败。 ``` SELECT * FROM Orders INNER JOIN Product ON Orders.productId = Product.id ``` **注意：**对于流式查询，计算查询结果所需的状态可能会无限增长，具体取决于不同输入行的数量。请提供具有有效保存间隔的查询配置，以防止过大的状态。有关详细信息，请参阅[Streaming Concepts](streaming.html)。 --- 操作：**外部Equi-join** 批量 流 结果更新 描述：目前，仅支持等连接，即具有至少一个带有等式谓词的连接条件的连接。不支持任意交叉或theta连接。**注意：**连接顺序未优化。表按照FROM子句中指定的顺序连接。确保以不产生交叉连接（笛卡尔积）的顺序指定表，这些表不受支持并且会导致查询失败。 ``` SELECT * FROM Orders LEFT JOIN Product ON Orders.productId = Product.id SELECT * FROM Orders RIGHT JOIN Product ON Orders.productId = Product.id SELECT * FROM Orders FULL OUTER JOIN Product ON Orders.productId = Product.id ``` **注意：**对于流式查询，计算查询结果所需的状态可能会无限增长，具体取决于不同输入行的数量。请提供具有有效保存间隔的查询配置，以防止过大的状态。有关详细信息，请参阅[Streaming Concepts](streaming.html)。 --- 操作：**Time-windowed Join** 批量 流 描述：**注意：**时间窗口连接是可以以流方式处理的常规连接的子集。时间窗口连接需要至少一个等连接谓词和一个限制双方时间的连接条件。这样的条件可以由两个适当的范围谓词（`<, <=, >=, >`），`BETWEEN`谓词或单个等式谓词来定义，其比较两个输入表的相同类型的[时间属性](streaming.html#time-attributes)（即，处理时间或事件时间）。例如，以下谓词是有效的窗口连接条件： * `ltime = rtime` * `ltime >= rtime AND ltime < rtime + INTERVAL '10' MINUTE` * `ltime BETWEEN rtime - INTERVAL '10' SECOND AND rtime + INTERVAL '5' SECOND` ``` SELECT * FROM Orders o, Shipments s WHERE o.id = s.orderId AND o.ordertime BETWEEN s.shiptime - INTERVAL '4' HOUR AND s.shiptime ``` 如果订单在收到订单后四小时发货，上面的示例将关联所有订单及其相应的货件。 --- 操作：**将数组扩展为关系** Batch Streaming 描述：尚未支持UnANDing WITH ORDINALITY。 ``` SELECT users, tag FROM Orders CROSS JOIN UNNEST(tags) AS t (tag) ``` --- 操作：**关联用户定义的表函数（UDTF）** 批量 流 描述：UDTF必须在TableEnvironment中注册。有关如何指定和注册UDTF的详细信息，请参阅[UDF文档](udfs.html)。内部联接 ``` SELECT users, tag FROM Orders, LATERAL TABLE(unnest_udtf(tags)) t AS tag ``` 左外连接 ``` SELECT users, tag FROM Orders LEFT JOIN LATERAL TABLE(unnest_udtf(tags)) t AS tag ON TRUE ``` **注意：**目前，`TRUE`对于横向表，只支持左外连接的谓词作为谓词。 ### 设置 算子操作 --- 操作：**Union** 批次 描述： ``` SELECT * FROM ( (SELECT user FROM Orders WHERE a % 2 = 0) UNION (SELECT user FROM Orders WHERE b = 0) ) ``` --- 操作：**UnionAll** Batch Streaming 描述： ``` SELECT * FROM ( (SELECT user FROM Orders WHERE a % 2 = 0) UNION ALL (SELECT user FROM Orders WHERE b = 0) ) ``` | **Intersect/ Except**批量 | ``` SELECT * FROM ( (SELECT user FROM Orders WHERE a % 2 = 0) INTERSECT (SELECT user FROM Orders WHERE b = 0) ) ``` ``` SELECT * FROM ( (SELECT user FROM Orders WHERE a % 2 = 0) EXCEPT (SELECT user FROM Orders WHERE b = 0) ) ``` --- 操作：**IN** 批量 流中 描述：如果表达式存在于给定的表子查询中，则返回true。子查询表必须包含一列。此列必须与表达式具有相同的数据类型。 ``` SELECT user, amount FROM Orders WHERE product IN ( SELECT product FROM NewProducts ) ``` **注意：**对于流式查询， 算子操作将在连接和组 算子操作中重写。计算查询结果所需的状态可能会无限增长，具体取决于不同输入行的数量。请提供具有有效保存间隔的查询配置，以防止过大的状态。有关详细信息，请参阅[Streaming Concepts](streaming.html)。 --- 操作：**Exists** 批量 流 描述：如果子查询至少返回一行，则返回true。仅在可以在连接和组 算子操作中重写 算子操作时才支持。 ``` SELECT user, amount FROM Orders WHERE product EXISTS ( SELECT product FROM NewProducts ) ``` **注意：**对于流式查询， 算子操作将在连接和组 算子操作中重写。计算查询结果所需的状态可能会无限增长，具体取决于不同输入行的数量。请提供具有有效保存间隔的查询配置，以防止过大的状态。有关详细信息，请参阅[Streaming Concepts](streaming.html)。 ### OrderBy＆Limit --- 操作：**Order By** 批量 流 描述：**注意：**流式查询的结果必须主要按升序[时间属性](streaming.html#time-attributes)排序。支持其他排序属性。 ``` SELECT * FROM Orders ORDER BY orderTime ``` --- 操作：**Limit** 批次 描述： ``` SELECT * FROM Orders LIMIT 3 ``` ### Insert --- 操作：**Insert** 批量 流处理 描述：输出表必须在TableEnvironment中[注册](common.html#register-a-tablesink)（请参阅[注册TableSink](common.html#register-a-tablesink)）。此外，已注册表的模式必须与查询的模式匹配。 ``` INSERT INTO OutputTable SELECT users, tag FROM Orders ``` ### GroupWindows 组窗口在`GROUP BY`SQL查询的子句中定义。就像具有常规`GROUP BY`子句的查询一样，带有`GROUP BY`包含组窗口函数的子句的查询会为每个组计算单个结果行。批处理和流表上的SQL支持以下组窗口函数。 | 组窗口函数 | 描述 | | --- | --- | | `TUMBLE(time_attr, interval)` | 定义翻滚时间窗口。翻滚时间窗口将行分配给具有固定持续时间（`interval`）的非重叠连续窗口。例如，5分钟的翻滚窗口以5分钟为间隔对行进行分组。可以在事件时间（流+批处理）或处理时间（流）上定义翻滚窗口。 | | `HOP(time_attr, interval, interval)` | 定义跳跃时间窗口（在 Table API中称为滑动窗口）。跳跃时间窗口具有固定的持续时间（第二`interval`参数）并且按指定的跳跃间隔（第一`interval`参数）跳跃。如果跳跃间隔小于窗口大小，则跳跃窗口重叠。因此，可以将行分配给多个窗口。例如，15分钟大小和5分钟跳跃间隔的跳跃窗口将每行分配给3个不同的15分钟大小的窗口，这些窗口以5分钟的间隔进行评估。可以在事件时间（流+批处理）或处理时间（流）上定义跳跃窗口。 | | `SESSION(time_attr, interval)` | 定义会话时间窗口。会话时间窗口没有固定的持续时间，但它们的界限由`interval`不活动时间定义，即如果在定义的间隙期间没有出现事件，则会话窗口关闭。例如，如果在30分钟不活动后观察到一行，则会开始一个30分钟间隙的会话窗口（否则该行将被添加到现有窗口中），如果在30分钟内未添加任何行，则会关闭。会话窗口可以在事件时间（流+批处理）或处理时间（流）上工作。 | #### 时间属性 对于流表的SQL查询，`time_attr`组窗口函数的参数必须引用指定行的处理时间或事件时间的有效时间属性。请参阅[时间属性文档](streaming.html#time-attributes)以了解如何定义时间属性。 对于批处理表上的SQL，`time_attr`组窗口函数的参数必须是类型的属性`TIMESTAMP`。 #### 选择组窗口开始和结束时间戳 可以使用以下辅助函数选择组窗口的开始和结束时间戳以及时间属性： | 辅助函数 | 描述 | | --- | --- | | `TUMBLE_START(time_attr, interval)` | 返回相应的翻滚，跳跃或会话窗口的包含下限的时间戳。 | | `HOP_START(time_attr, interval, interval)` | | | `SESSION_START(time_attr, interval)` | | | `TUMBLE_END(time_attr, interval)` | 返回相应的翻滚，跳跃或会话窗口的_独占_上限的时间戳。**注意：**独占上限时间戳_不能_在后续基于时间的 算子操作中用作[行时属性](streaming.html#time-attributes)，例如[时间窗口连接](#joins)和[组窗口或窗口聚合](#aggregations)。 | | `HOP_END(time_attr, interval, interval)` | | | `SESSION_END(time_attr, interval)` | | | `TUMBLE_ROWTIME(time_attr, interval)` | 返回相应的翻滚，跳跃或会话窗口的_包含_上限的时间戳。结果属性是[rowtime属性](streaming.html#time-attributes)，可用于后续基于时间的 算子操作，例如[时间窗口连接](#joins)和[组窗口或窗口聚合](#aggregations)。 | | `HOP_ROWTIME(time_attr, interval, interval)` | | | `SESSION_ROWTIME(time_attr, interval)` | | | `TUMBLE_PROCTIME(time_attr, interval)` | 返回[proctime属性](streaming.html#time-attributes)，该[属性](streaming.html#time-attributes)可用于后续基于时间的 算子操作，例如[时间窗口连接](#joins)和[组窗口或窗口聚合](#aggregations)。 | | `HOP_PROCTIME(time_attr, interval, interval)` | | | `SESSION_PROCTIME(time_attr, interval)` | | _注意：_必须使用与`GROUP BY`子句中的组窗口函数完全相同的参数调用辅助函数。 以下示例显示如何在流表上指定具有组窗口的SQL查询。 * [**Java**](#tab_java_1) * [**Scala**](#tab_scala_1) ``` StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment(); StreamTableEnvironment tableEnv = TableEnvironment.getTableEnvironment(env); // ingest a DataStream from an external source DataStream> ds = env.addSource(...); // register the DataStream as table "Orders" tableEnv.registerDataStream("Orders", ds, "user, product, amount, proctime.proctime, rowtime.rowtime"); // compute SUM(amount) per day (in event-time) Table result1 = tableEnv.sqlQuery( "SELECT user, " + " TUMBLE_START(rowtime, INTERVAL '1' DAY) as wStart, " + " SUM(amount) FROM Orders " + "GROUP BY TUMBLE(rowtime, INTERVAL '1' DAY), user"); // compute SUM(amount) per day (in processing-time) Table result2 = tableEnv.sqlQuery( "SELECT user, SUM(amount) FROM Orders GROUP BY TUMBLE(proctime, INTERVAL '1' DAY), user"); // compute every hour the SUM(amount) of the last 24 hours in event-time Table result3 = tableEnv.sqlQuery( "SELECT product, SUM(amount) FROM Orders GROUP BY HOP(rowtime, INTERVAL '1' HOUR, INTERVAL '1' DAY), product"); // compute SUM(amount) per session with 12 hour inactivity gap (in event-time) Table result4 = tableEnv.sqlQuery( "SELECT user, " + " SESSION_START(rowtime, INTERVAL '12' HOUR) AS sStart, " + " SESSION_ROWTIME(rowtime, INTERVAL '12' HOUR) AS snd, " + " SUM(amount) " + "FROM Orders " + "GROUP BY SESSION(rowtime, INTERVAL '12' HOUR), user"); ``` ``` val env = StreamExecutionEnvironment.getExecutionEnvironment val tableEnv = TableEnvironment.getTableEnvironment(env) // read a DataStream from an external source val ds: DataStream[(Long, String, Int)] = env.addSource(...) // register the DataStream under the name "Orders" tableEnv.registerDataStream("Orders", ds, 'user, 'product, 'amount, 'proctime.proctime, 'rowtime.rowtime) // compute SUM(amount) per day (in event-time) val result1 = tableEnv.sqlQuery( """ |SELECT | user, | TUMBLE_START(rowtime, INTERVAL '1' DAY) as wStart, | SUM(amount) | FROM Orders | GROUP BY TUMBLE(rowtime, INTERVAL '1' DAY), user """.stripMargin) // compute SUM(amount) per day (in processing-time) val result2 = tableEnv.sqlQuery( "SELECT user, SUM(amount) FROM Orders GROUP BY TUMBLE(proctime, INTERVAL '1' DAY), user") // compute every hour the SUM(amount) of the last 24 hours in event-time val result3 = tableEnv.sqlQuery( "SELECT product, SUM(amount) FROM Orders GROUP BY HOP(rowtime, INTERVAL '1' HOUR, INTERVAL '1' DAY), product") // compute SUM(amount) per session with 12 hour inactivity gap (in event-time) val result4 = tableEnv.sqlQuery( """ |SELECT | user, | SESSION_START(rowtime, INTERVAL '12' HOUR) AS sStart, | SESSION_END(rowtime, INTERVAL '12' HOUR) AS sEnd, | SUM(amount) | FROM Orders | GROUP BY SESSION(rowtime(), INTERVAL '12' HOUR), user """.stripMargin) ``` ## 数据类型 SQL运行时构建于Flink的DataSet和DataStream API之上。在内部，它还使用Flink `TypeInformation`来定义数据类型。完全支持的类型列在`org.apache.flink.table.api.Types`。下表总结了SQL类型， Table API类型和生成的Java类之间的关系。 | Table API | SQL | Java类型 | | --- | --- | --- | | `Types.STRING` | `VARCHAR` | `java.lang.String` | | `Types.BOOLEAN` | `BOOLEAN` | `java.lang.Boolean` | | `Types.BYTE` | `TINYINT` | `java.lang.Byte` | | `Types.SHORT` | `SMALLINT` | `java.lang.Short` | | `Types.INT` | `INTEGER, INT` | `java.lang.Integer` | | `Types.LONG` | `BIGINT` | `java.lang.Long` | | `Types.FLOAT` | `REAL, FLOAT` | `java.lang.Float` | | `Types.DOUBLE` | `DOUBLE` | `java.lang.Double` | | `Types.DECIMAL` | `DECIMAL` | `java.math.BigDecimal` | | `Types.SQL_DATE` | `DATE` | `java.sql.Date` | | `Types.SQL_TIME` | `TIME` | `java.sql.Time` | | `Types.SQL_TIMESTAMP` | `TIMESTAMP(3)` | `java.sql.Timestamp` | | `Types.INTERVAL_MONTHS` | `INTERVAL YEAR TO MONTH` | `java.lang.Integer` | | `Types.INTERVAL_MILLIS` | `INTERVAL DAY TO SECOND(3)` | `java.lang.Long` | | `Types.PRIMITIVE_ARRAY` | `ARRAY` | 例如 `int[]` | | `Types.OBJECT_ARRAY` | `ARRAY` | 例如 `java.lang.Byte[]` | | `Types.MAP` | `MAP` | `java.util.HashMap` | | `Types.MULTISET` | `MULTISET` | 例如，`java.util.HashMap<String, Integer>`对于多重集合`String` | | `Types.ROW` | `ROW` | `org.apache.flink.types.Row` | 通用类型和（嵌套）复合类型（例如，POJO，元组，Row，Scala案例类）也可以是行的字段。 可以使用[值访问函数](functions.html#value-access-functions)访问具有任意嵌套的复合类型的字段。 通用类型被视为黑盒子，可以由[用户定义的函数](udfs.html)传递或处理。 ## 保存关键字 虽然并非每个SQL函数都已实现，但某些字符串组合已被保存为关键字以供将来使用。如果要将以下字符串之一用作字段名称，请确保使用反引号将其包围（例如``value``，``count``）。 ``` A, ABS, ABSOLUTE, ACTION, ADA, ADD, ADMIN, AFTER, ALL, ALLOCATE, ALLOW, ALTER, ALWAYS, AND, ANY, ARE, ARRAY, AS, ASC, ASENSITIVE, ASSERTION, ASSIGNMENT, ASYMMETRIC, AT, ATOMIC, ATTRIBUTE, ATTRIBUTES, AUTHORIZATION, AVG, BEFORE, BEGIN, BERNOULLI, BETWEEN, BIGINT, BINARY, BIT, BLOB, BOOLEAN, BOTH, BREADTH, BY, C, CALL, CALLED, CARDINALITY, CASCADE, CASCADED, CASE, CAST, CATALOG, CATALOG_NAME, CEIL, CEILING, CENTURY, CHAIN, CHAR, CHARACTER, CHARACTERISTICS, CHARACTERS, CHARACTER_LENGTH, CHARACTER_SET_CATALOG, CHARACTER_SET_NAME, CHARACTER_SET_SCHEMA, CHAR_LENGTH, CHECK, CLASS_ORIGIN, CLOB, CLOSE, COALESCE, COBOL, COLLATE, COLLATION, COLLATION_CATALOG, COLLATION_NAME, COLLATION_SCHEMA, COLLECT, COLUMN, COLUMN_NAME, COMMAND_FUNCTION, COMMAND_FUNCTION_CODE, COMMIT, COMMITTED, CONDITION, CONDITION_NUMBER, CONNECT, CONNECTION, CONNECTION_NAME, CONSTRAINT, CONSTRAINTS, CONSTRAINT_CATALOG, CONSTRAINT_NAME, CONSTRAINT_SCHEMA, CONSTRUCTOR, CONTAINS, CONTINUE, CONVERT, CORR, CORRESPONDING, COUNT, COVAR_POP, COVAR_SAMP, CREATE, CROSS, CUBE, CUME_DIST, CURRENT, CURRENT_CATALOG, CURRENT_DATE, CURRENT_DEFAULT_TRANSFORM_GROUP, CURRENT_PATH, CURRENT_ROLE, CURRENT_SCHEMA, CURRENT_TIME, CURRENT_TIMESTAMP, CURRENT_TRANSFORM_GROUP_FOR_TYPE, CURRENT_USER, CURSOR, CURSOR_NAME, CYCLE, DATA, DATABASE, DATE, DATETIME_INTERVAL_CODE, DATETIME_INTERVAL_PRECISION, DAY, DEALLOCATE, DEC, DECADE, DECIMAL, DECLARE, DEFAULT, DEFAULTS, DEFERRABLE, DEFERRED, DEFINED, DEFINER, DEGREE, DELETE, DENSE_RANK, DEPTH, DEREF, DERIVED, DESC, DESCRIBE, DESCRIPTION, DESCRIPTOR, DETERMINISTIC, DIAGNOSTICS, DISALLOW, DISCONNECT, DISPATCH, DISTINCT, DOMAIN, DOUBLE, DOW, DOY, DROP, DYNAMIC, DYNAMIC_FUNCTION, DYNAMIC_FUNCTION_CODE, EACH, ELEMENT, ELSE, END, END-EXEC, EPOCH, EQUALS, ESCAPE, EVERY, EXCEPT, EXCEPTION, EXCLUDE, EXCLUDING, EXEC, EXECUTE, EXISTS, EXP, EXPLAIN, EXTEND, EXTERNAL, EXTRACT, FALSE, FETCH, FILTER, FINAL, FIRST, FIRST_VALUE, FLOAT, FLOOR, FOLLOWING, FOR, FOREIGN, FORTRAN, FOUND, FRAC_SECOND, FREE, FROM, FULL, FUNCTION, FUSION, G, GENERAL, GENERATED, GET, GLOBAL, GO, GOTO, GRANT, GRANTED, GROUP, GROUPING, HAVING, HIERARCHY, HOLD, HOUR, IDENTITY, IMMEDIATE, IMPLEMENTATION, IMPORT, IN, INCLUDING, INCREMENT, INDICATOR, INITIALLY, INNER, INOUT, INPUT, INSENSITIVE, INSERT, INSTANCE, INSTANTIABLE, INT, INTEGER, INTERSECT, INTERSECTION, INTERVAL, INTO, INVOKER, IS, ISOLATION, JAVA, JOIN, K, KEY, KEY_MEMBER, KEY_TYPE, LABEL, LANGUAGE, LARGE, LAST, LAST_VALUE, LATERAL, LEADING, LEFT, LENGTH, LEVEL, LIBRARY, LIKE, LIMIT, LN, LOCAL, LOCALTIME, LOCALTIMESTAMP, LOCATOR, LOWER, M, MAP, MATCH, MATCHED, MAX, MAXVALUE, MEMBER, MERGE, MESSAGE_LENGTH, MESSAGE_OCTET_LENGTH, MESSAGE_TEXT, METHOD, MICROSECOND, MILLENNIUM, MIN, MINUTE, MINVALUE, MOD, MODIFIES, MODULE, MONTH, MORE, MULTISET, MUMPS, NAME, NAMES, NATIONAL, NATURAL, NCHAR, NCLOB, NESTING, NEW, NEXT, NO, NONE, NORMALIZE, NORMALIZED, NOT, NULL, NULLABLE, NULLIF, NULLS, NUMBER, NUMERIC, OBJECT, OCTETS, OCTET_LENGTH, OF, OFFSET, OLD, ON, ONLY, OPEN, OPTION, OPTIONS, OR, ORDER, ORDERING, ORDINALITY, OTHERS, OUT, OUTER, OUTPUT, OVER, OVERLAPS, OVERLAY, OVERRIDING, PAD, PARAMETER, PARAMETER_MODE, PARAMETER_NAME, PARAMETER_ORDINAL_POSITION, PARAMETER_SPECIFIC_CATALOG, PARAMETER_SPECIFIC_NAME, PARAMETER_SPECIFIC_SCHEMA, PARTIAL, PARTITION, PASCAL, PASSTHROUGH, PATH, PERCENTILE_CONT, PERCENTILE_DISC, PERCENT_RANK, PLACING, PLAN, PLI, POSITION, POWER, PRECEDING, PRECISION, PREPARE, PRESERVE, PRIMARY, PRIOR, PRIVILEGES, PROCEDURE, PUBLIC, QUARTER, RANGE, RANK, READ, READS, REAL, RECURSIVE, REF, REFERENCES, REFERENCING, REGR_AVGX, REGR_AVGY, REGR_COUNT, REGR_INTERCEPT, REGR_R2, REGR_SLOPE, REGR_SXX, REGR_SXY, REGR_SYY, RELATIVE, RELEASE, REPEATABLE, RESET, RESTART, RESTRICT, RESULT, RETURN, RETURNED_CARDINALITY, RETURNED_LENGTH, RETURNED_OCTET_LENGTH, RETURNED_SQLSTATE, RETURNS, REVOKE, RIGHT, ROLE, ROLLBACK, ROLLUP, ROUTINE, ROUTINE_CATALOG, ROUTINE_NAME, ROUTINE_SCHEMA, ROW, ROWS, ROW_COUNT, ROW_NUMBER, SAVEPOINT, SCALE, SCHEMA, SCHEMA_NAME, SCOPE, SCOPE_CATALOGS, SCOPE_NAME, SCOPE_SCHEMA, SCROLL, SEARCH, SECOND, SECTION, SECURITY, SELECT, SELF, SENSITIVE, SEQUENCE, SERIALIZABLE, SERVER, SERVER_NAME, SESSION, SESSION_USER, SET, SETS, SIMILAR, SIMPLE, SIZE, SMALLINT, SOME, SOURCE, SPACE, SPECIFIC, SPECIFICTYPE, SPECIFIC_NAME, SQL, SQLEXCEPTION, SQLSTATE, SQLWARNING, SQL_TSI_DAY, SQL_TSI_FRAC_SECOND, SQL_TSI_HOUR, SQL_TSI_MICROSECOND, SQL_TSI_MINUTE, SQL_TSI_MONTH, SQL_TSI_QUARTER, SQL_TSI_SECOND, SQL_TSI_WEEK, SQL_TSI_YEAR, SQRT, START, STATE, STATEMENT, STATIC, STDDEV_POP, STDDEV_SAMP, STREAM, STRUCTURE, STYLE, SUBCLASS_ORIGIN, SUBMULTISET, SUBSTITUTE, SUBSTRING, SUM, SYMMETRIC, SYSTEM, SYSTEM_USER, TABLE, TABLESAMPLE, TABLE_NAME, TEMPORARY, THEN, TIES, TIME, TIMESTAMP, TIMESTAMPADD, TIMESTAMPDIFF, TIMEZONE_HOUR, TIMEZONE_MINUTE, TINYINT, TO, TOP_LEVEL_COUNT, TRAILING, TRANSACTION, TRANSACTIONS_ACTIVE, TRANSACTIONS_COMMITTED, TRANSACTIONS_ROLLED_BACK, TRANSFORM, TRANSFORMS, TRANSLATE, TRANSLATION, TREAT, TRIGGER, TRIGGER_CATALOG, TRIGGER_NAME, TRIGGER_SCHEMA, TRIM, TRUE, TYPE, UESCAPE, UNBOUNDED, UNCOMMITTED, UNDER, UNION, UNIQUE, UNKNOWN, UNNAMED, UNNEST, UPDATE, UPPER, UPSERT, USAGE, USER, USER_DEFINED_TYPE_CATALOG, USER_DEFINED_TYPE_CODE, USER_DEFINED_TYPE_NAME, USER_DEFINED_TYPE_SCHEMA, USING, VALUE, VALUES, VARBINARY, VARCHAR, VARYING, VAR_POP, VAR_SAMP, VERSION, VIEW, WEEK, WHEN, WHENEVER, WHERE, WIDTH_BUCKET, WINDOW, WITH, WITHIN, WITHOUT, WORK, WRAPPER, WRITE, XML, YEAR, ZONE ```